From 69bb5f7e654fe60d75bd35c32e2b71e4370dc76b Mon Sep 17 00:00:00 2001 From: Lilian Lee Date: Fri, 23 Aug 2024 16:34:43 +0800 Subject: [PATCH] This is an automated cherry-pick of #18672 Signed-off-by: ti-chi-bot --- data-type-string.md | 16 +- develop/dev-guide-transaction-restraints.md | 2 +- error-codes.md | 2 +- faq/backup-and-restore-faq.md | 329 ++++++++++ faq/migration-tidb-faq.md | 2 +- releases/release-6.1.1.md | 6 +- releases/release-6.1.2.md | 6 +- releases/release-6.1.4.md | 2 +- releases/release-6.1.7.md | 4 +- releases/release-6.3.0.md | 450 ++++++++++++++ releases/release-6.4.0.md | 486 +++++++++++++++ releases/release-6.5.1.md | 187 ++++++ releases/release-6.5.10.md | 148 +++++ releases/release-6.5.2.md | 108 ++++ releases/release-6.5.3.md | 139 +++++ releases/release-6.5.4.md | 201 +++++++ releases/release-6.5.6.md | 180 ++++++ releases/release-6.6.0.md | 626 ++++++++++++++++++++ releases/release-7.0.0.md | 512 ++++++++++++++++ releases/release-7.1.0.md | 551 +++++++++++++++++ releases/release-7.1.1.md | 157 +++++ releases/release-7.1.3.md | 162 +++++ releases/release-7.1.4.md | 185 ++++++ releases/release-7.1.5.md | 119 ++++ releases/release-7.2.0.md | 332 +++++++++++ releases/release-7.4.0.md | 500 ++++++++++++++++ releases/release-7.5.0.md | 305 ++++++++++ releases/release-7.5.1.md | 232 ++++++++ releases/release-7.5.2.md | 253 ++++++++ releases/release-7.5.3.md | 130 ++++ releases/release-7.6.0.md | 542 +++++++++++++++++ releases/release-8.0.0.md | 601 +++++++++++++++++++ releases/release-8.1.0.md | 360 +++++++++++ releases/release-8.2.0.md | 410 +++++++++++++ releases/release-8.3.0.md | 436 ++++++++++++++ system-variables.md | 51 ++ tidb-configuration-file.md | 2 +- tidb-limitations.md | 2 +- 38 files changed, 8714 insertions(+), 22 deletions(-) create mode 100644 faq/backup-and-restore-faq.md create mode 100644 releases/release-6.3.0.md create mode 100644 releases/release-6.4.0.md create mode 100644 releases/release-6.5.1.md create mode 100644 releases/release-6.5.10.md create mode 100644 releases/release-6.5.2.md create mode 100644 releases/release-6.5.3.md create mode 100644 releases/release-6.5.4.md create mode 100644 releases/release-6.5.6.md create mode 100644 releases/release-6.6.0.md create mode 100644 releases/release-7.0.0.md create mode 100644 releases/release-7.1.0.md create mode 100644 releases/release-7.1.1.md create mode 100644 releases/release-7.1.3.md create mode 100644 releases/release-7.1.4.md create mode 100644 releases/release-7.1.5.md create mode 100644 releases/release-7.2.0.md create mode 100644 releases/release-7.4.0.md create mode 100644 releases/release-7.5.0.md create mode 100644 releases/release-7.5.1.md create mode 100644 releases/release-7.5.2.md create mode 100644 releases/release-7.5.3.md create mode 100644 releases/release-7.6.0.md create mode 100644 releases/release-8.0.0.md create mode 100644 releases/release-8.1.0.md create mode 100644 releases/release-8.2.0.md create mode 100644 releases/release-8.3.0.md diff --git a/data-type-string.md b/data-type-string.md index 21dee046869dd..990c52c571bf0 100644 --- a/data-type-string.md +++ b/data-type-string.md @@ -55,12 +55,12 @@ TINYTEXT [CHARACTER SET charset_name] [COLLATE collation_name] -The `MEDIUMTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `MEDIUMTEXT` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `MEDIUMTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `MEDIUMTEXT` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. -The `MEDIUMTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `MEDIUMTEXT` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `MEDIUMTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `MEDIUMTEXT` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. @@ -72,12 +72,12 @@ MEDIUMTEXT [CHARACTER SET charset_name] [COLLATE collation_name] -The `LONGTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `LONGTEXT` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `LONGTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `LONGTEXT` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. -The `LONGTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `LONGTEXT` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `LONGTEXT` type is similar to the [`TEXT` type](#text-type). The difference is that the maximum column length of `LONGTEXT` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. @@ -121,12 +121,12 @@ TINYBLOB -The `MEDIUMBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `MEDIUMBLOB` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `MEDIUMBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `MEDIUMBLOB` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. -The `MEDIUMBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `MEDIUMBLOB` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `MEDIUMBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `MEDIUMBLOB` is 16,777,215. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. @@ -138,12 +138,12 @@ MEDIUMBLOB -The `LONGBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `LONGBLOB` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `LONGBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `LONGBLOB` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. -The `LONGBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `LONGBLOB` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v50), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. +The `LONGBLOB` type is similar to the [`BLOB` type](#blob-type). The difference is that the maximum column length of `LONGBLOB` is 4,294,967,295. But due to the limitation of [`txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v4010-and-v500), the maximum storage size of a single row in TiDB is 6 MiB by default and can be increased to 120 MiB by changing the configuration. diff --git a/develop/dev-guide-transaction-restraints.md b/develop/dev-guide-transaction-restraints.md index 982a29621e41b..b4e61ac3146bc 100644 --- a/develop/dev-guide-transaction-restraints.md +++ b/develop/dev-guide-transaction-restraints.md @@ -707,7 +707,7 @@ mysql> SELECT * FROM T2; The basic principle is to limit the size of the transaction. At the KV level, TiDB has a restriction on the size of a single transaction. At the SQL level, one row of data is mapped to one KV entry, and each additional index will add one KV entry. The restriction is as follows at the SQL level: -- The maximum single row record size is `120 MB`. You can configure it by `performance.txn-entry-size-limit` for TiDB v5.0 and later versions. The value is `6 MB` for earlier versions. +- The maximum single row record size is `120 MB`. You can adjust it by using the `performance.txn-entry-size-limit` configuration parameter of tidb-server for TiDB v4.0.10 and later v4.0.x versions, TiDB v5.0.0 and later versions. The value is `6 MB` for versions earlier than v4.0.10. - The maximum single transaction size supported is `10 GB`. You can configure it by `performance.txn-total-size-limit` for TiDB v4.0 and later versions. The value is `100 MB` for earlier versions. Note that for both the size restrictions and row restrictions, you should also consider the overhead of encoding and additional keys for the transaction during the transaction execution. To achieve optimal performance, it is recommended to write one transaction every 100 ~ 500 rows. diff --git a/error-codes.md b/error-codes.md index e6407ccdb5807..8e3463be90fc6 100644 --- a/error-codes.md +++ b/error-codes.md @@ -89,7 +89,7 @@ TiDB is compatible with the error codes in MySQL, and in most cases returns the The single Key-Value pair being written is too large. The largest single Key-Value pair supported in TiDB is 6 MB by default. - If a pair exceeds this limit, you need to properly adjust the [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50) configuration value to relax the limit. + If a pair exceeds this limit, you need to properly adjust the [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500) configuration value to relax the limit. * Error Number: 8026 diff --git a/faq/backup-and-restore-faq.md b/faq/backup-and-restore-faq.md new file mode 100644 index 0000000000000..936c5f4dda95c --- /dev/null +++ b/faq/backup-and-restore-faq.md @@ -0,0 +1,329 @@ +--- +title: Backup & Restore FAQs +summary: Learn about Frequently Asked Questions (FAQs) and the solutions of backup and restore. +aliases: ['/docs/dev/br/backup-and-restore-faq/','/tidb/dev/pitr-troubleshoot/','/tidb/dev/pitr-known-issues/'] +--- + +# Backup & Restore FAQs + +This document lists the frequently asked questions (FAQs) and the solutions of TiDB Backup & Restore (BR). + +## What should I do to quickly recover data after mistakenly deleting or updating data? + +TiDB v6.4.0 introduces the flashback feature. You can use this feature to quickly recover data within the GC time to a specified point in time. Therefore, if misoperations occur, you can use this feature to recover data. For details, see [Flashback Cluster](/sql-statements/sql-statement-flashback-cluster.md) and [Flashback Database](/sql-statements/sql-statement-flashback-database.md). + +## In TiDB v5.4.0 and later versions, when backup tasks are performed on the cluster under a heavy workload, why does the speed of backup tasks become slow? + +Starting from TiDB v5.4.0, BR introduces the auto-tune feature for backup tasks. For clusters in v5.4.0 or later versions, this feature is enabled by default. When the cluster workload is heavy, the feature limits the resources used by backup tasks to reduce the impact on the online cluster. For more information, refer to [Backup Auto-Tune](/br/br-auto-tune.md). + +TiKV supports [dynamically configuring](/tikv-control.md#modify-the-tikv-configuration-dynamically) the auto-tune feature. You can enable or disable the feature by the following methods without restarting your cluster: + +- Disable auto-tune: Set the TiKV configuration item [`backup.enable-auto-tune`](/tikv-configuration-file.md#enable-auto-tune-new-in-v540) to `false`. +- Enable auto-tune: Set `backup.enable-auto-tune` to `true`. For clusters upgraded from v5.3.x to v5.4.0 or later versions, the auto-tune feature is disabled by default. You need to manually enable it. + +To use `tikv-ctl` to enable or disable auto-tune, refer to [Use auto-tune](/br/br-auto-tune.md#use-auto-tune). + +In addition, auto-tune reduces the default number of threads used by backup tasks. For details, see `backup.num-threads`](/tikv-configuration-file.md#num-threads-1). Therefore, on the Grafana Dashboard, the speed, CPU usage, and I/O resource utilization used by backup tasks are lower than those of versions earlier than v5.4.0. Before v5.4.0, the default value of `backup.num-threads` was `CPU * 0.75`, that is, the number of threads used by backup tasks makes up 75% of the logical CPU cores. The maximum value of it was `32`. Starting from v5.4.0, the default value of this configuration item is `CPU * 0.5`, and its maximum value is `8`. + +When you perform backup tasks on an offline cluster, to speed up the backup, you can modify the value of `backup.num-threads` to a larger number using `tikv-ctl`. + +## PITR issues + +### What is the difference between [PITR](/br/br-pitr-guide.md) and [cluster flashback](/sql-statements/sql-statement-flashback-cluster.md)? + +From the perspective of use cases, PITR is usually used to restore the data of a cluster to a specified point in time when the cluster is completely out of service or the data is corrupted and cannot be recovered using other solutions. To use PITR, you need a new cluster for data recovery. The cluster flashback feature is specifically designed for the data error scenarios caused by user mis-operations or other factors, which allows you to restore the data of a cluster in-place to the latest timestamp before the data errors occur. + +In most cases, flashback is a better recovery solution than PITR for data errors caused by human mistakes, as it has a much shorter RPO (close to zero) and RTO. However, when a cluster is completely unavailable, because flashback cannot run at this time, PITR is the only solution to recover the cluster in this case. Therefore, PITR is always a must-have solution when you develop database disaster recovery strategies, even though it has a longer RPO (up to 5 minutes) and RTO than flashback. + +### When the upstream database imports data using TiDB Lightning in the physical import mode, the log backup feature becomes unavailable. Why? + +Currently, the log backup feature is not fully adapted to TiDB Lightning. Therefore, data imported in the physical mode of TiDB Lightning cannot be backed up into log data + +In upstream clusters where you create log backup tasks, avoid using the TiDB Lightning physical mode to import data. Instead, you can use TiDB Lightning logical mode. If you do need to use the physical mode, perform a snapshot backup after the import is complete, so that PITR can be restored to the time point after the snapshot backup. + +### The cluster has recovered from the network partition failure, but the checkpoint of the log backup task progress still does not resume. Why? + +Issue: [#13126](https://github.com/tikv/tikv/issues/13126) + +After a network partition failure in the cluster, the backup task cannot continue backing up logs. After a certain retry time, the task will be set to `ERROR` state. At this point, the backup task has stopped. + +To resolve this issue, you need to manually execute the `br log resume` command to resume the log backup task. + +## After restoring a downstream cluster using the `br restore point` command, data cannot be accessed from TiFlash. What should I do? + +Currently, PITR does not support writing data directly to TiFlash during the restore phase. Instead, br command-line tool executes the `ALTER TABLE table_name SET TIFLASH REPLICA ***` DDL to replicate the data. Therefore, TiFlash replicas are not available immediately after PITR completes data restore. Instead, you need to wait for a certain period of time for the data to be replicated from TiKV nodes. To check the replication progress, check the `progress` information in the `INFORMATION_SCHEMA.tiflash_replica` table. + +### What should I do if the `status` of a log backup task becomes `ERROR`? + +During a log backup task, the task status becomes `ERROR` if it fails and cannot be recovered after retrying. The following is an example: + +```shell +br log status --pd x.x.x.x:2379 + +● Total 1 Tasks. +> #1 < + name: task1 + status: ○ ERROR + start: 2022-07-25 13:49:02.868 +0000 + end: 2090-11-18 14:07:45.624 +0000 + storage: s3://tmp/br-log-backup0ef49055-5198-4be3-beab-d382a2189efb/Log + speed(est.): 0.00 ops/s + checkpoint[global]: 2022-07-25 14:46:50.118 +0000; gap=11h31m29s + error[store=1]: KV:LogBackup:RaftReq +error-happen-at[store=1]: 2022-07-25 14:54:44.467 +0000; gap=11h23m35s + error-message[store=1]: retry time exceeds: and error failed to get initial snapshot: failed to get the snapshot (region_id = 94812): Error during requesting raftstore: message: "read index not ready, reason can not read index due to merge, region 94812" read_index_not_ready { reason: "can not read index due to merge" region_id: 94812 }: failed to get initial snapshot: failed to get the snapshot (region_id = 94812): Error during requesting raftstore: message: "read index not ready, reason can not read index due to merge, region 94812" read_index_not_ready { reason: "can not read index due to merge" region_id: 94812 }: failed to get initial snapshot: failed to get the snapshot (region_id = 94812): Error during requesting raftstore: message: "read index not ready, reason can not read index due to merge, region 94812" read_index_not_ready { reason: "can not read index due to merge" region_id: 94812 } +``` + +To address this problem, check the error message for the cause and perform as instructed. After the problem is addressed, run the following command to resume the task: + +```shell +br log resume --task-name=task1 --pd x.x.x.x:2379 +``` + +After the backup task is resumed, you can check the status using `br log status`. The backup task continues when the task status becomes `NORMAL`. + +```shell +● Total 1 Tasks. +> #1 < + name: task1 + status: ● NORMAL + start: 2022-07-25 13:49:02.868 +0000 + end: 2090-11-18 14:07:45.624 +0000 + storage: s3://tmp/br-log-backup0ef49055-5198-4be3-beab-d382a2189efb/Log + speed(est.): 15509.75 ops/s +checkpoint[global]: 2022-07-25 14:46:50.118 +0000; gap=6m28s +``` + +> **Note:** +> +> This feature backs up multiple versions of data. When a long backup task fails and the status becomes `ERROR`, the checkpoint data of this task is set as a `safe point`, and the data of the `safe point` will not be garbage collected within 24 hours. Therefore, the backup task continues from the last checkpoint after resuming the error. If the task fails for more than 24 hours and the last checkpoint data has been garbage collected, an error will be reported when you resume the task. In this case, you can only run the `br log stop` command to stop the task first and then start a new backup task. + +### What should I do if the error message `ErrBackupGCSafepointExceeded` is returned when using the `br log resume` command to resume a suspended task? + +```shell +Error: failed to check gc safePoint, checkpoint ts 433177834291200000: GC safepoint 433193092308795392 exceed TS 433177834291200000: [BR:Backup:ErrBackupGCSafepointExceeded]backup GC safepoint exceeded +``` + +After you pause a log backup task, to prevent the MVCC data from being garbage collected, the pausing task program sets the current checkpoint as the service safepoint automatically. This ensures that the MVCC data generated within 24 hours can remain. If the MVCC data of the backup checkpoint has been generated for more than 24 hours, the data of the checkpoint will be garbage collected, and the backup task is unable to resume. + +To address this problem, delete the current task using `br log stop`, and then create a log backup task using `br log start`. At the same time, you can perform a full backup for subsequent PITR. + +## Feature compatibility issues + +### Why does data restored using br command-line tool cannot be replicated to the upstream cluster of TiCDC or Drainer? + ++ **The data restored using BR cannot be replicated to the downstream**. This is because BR directly imports SST files but the downstream cluster currently cannot obtain these files from the upstream. + ++ Before v4.0.3, DDL jobs generated during the restore might cause unexpected DDL executions in TiCDC/Drainer. Therefore, if you need to perform restore on the upstream cluster of TiCDC/Drainer, add all tables restored using br command-line tool to the TiCDC/Drainer block list. + +You can use [`filter.rules`](https://github.com/pingcap/tiflow/blob/7c3c2336f98153326912f3cf6ea2fbb7bcc4a20c/cmd/changefeed.toml#L16) to configure the block list for TiCDC and use [`syncer.ignore-table`](/tidb-binlog/tidb-binlog-configuration-file.md#ignore-table) to configure the block list for Drainer. + +### Why is `new_collation_enabled` mismatch reported during restore? + +Since TiDB v6.0.0, the default value of [`new_collations_enabled_on_first_bootstrap`](/tidb-configuration-file.md#new_collations_enabled_on_first_bootstrap) has changed from `false` to `true`. BR backs up the `new_collation_enabled` configuration in the `mysql.tidb` table of the upstream cluster and then checks whether the value of this configuration is consistent between the upstream and downstream clusters. If the value is consistent, BR safely restores the data backed up in the upstream cluster to the downstream cluster. If the value is inconsistent, BR does not perform the data restore and reports an error. + +Suppose that you have backed up the data in a TiDB cluster of an earlier version of v6.0.0, and you want to restore this data to a TiDB cluster of v6.0.0 or later versions. In this situation, you need to manually check whether the value of `new_collations_enabled_on_first_bootstrap` is consistent between the upstream and downstream clusters: + +- If the value is consistent, you can add `--check-requirements=false` to the restore command to skip this configuration check. +- If the value is inconsistent, and you forcibly perform the restore, BR reports a data validation error. + +### Why does an error occur when I restore placement rules to a cluster? + +Before v6.0.0, BR does not support [placement rules](/placement-rules-in-sql.md). Starting from v6.0.0, BR supports placement rules and introduces a command-line option `--with-tidb-placement-mode=strict/ignore` to control the backup and restore mode of placement rules. With the default value `strict`, BR imports and validates placement rules, but ignores all placement rules when the value is `ignore`. + +## Data restore issues + +### What should I do to handle the `Io(Os...)` error? + +Almost all of these problems are system call errors that occur when TiKV writes data to the disk, for example, `Io(Os {code: 13, kind: PermissionDenied...})` or `Io(Os {code: 2, kind: NotFound...})`. + +To address such problems, first check the mounting method and the file system of the backup directory, and try to back up data to another folder or another hard disk. + +For example, you might encounter the `Code: 22(invalid argument)` error when backing up data to the network disk built by `samba`. + +### What should I do to handle the `rpc error: code = Unavailable desc =...` error occurred in restore? + +This error might occur when the capacity of the cluster to restore is insufficient. You can further confirm the cause by checking the monitoring metrics of this cluster or the TiKV log. + +To handle this issue, you can try to scale out the cluster resources, reduce the value of `tikv-max-restore-concurrency` for the restore, and enable the `ratelimit` option. + +### What should I do if the restore fails with the error message `the entry too large, the max entry size is 6291456, the size of data is 7690800`? + +You can try to reduce the number of tables to be created in a batch by setting `--ddl-batch-size` to `128` or a smaller value. + +When using BR to restore the backup data with the value of [`--ddl-batch-size`](/br/br-batch-create-table.md#use-batch-create-table) greater than `1`, TiDB writes a DDL job of table creation to the DDL jobs queue that is maintained by TiKV. At this time, the total size of all tables schema sent by TiDB at one time should not exceed 6 MB, because the maximum value of job messages is `6 MB` by default (it is **not recommended** to modify this value. For details, see [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500) and [`raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size)). Therefore, if you set `--ddl-batch-size` to an excessively large value, the schema size of the tables sent by TiDB in a batch at one time exceeds the specified value, which causes BR to report the `entry too large, the max entry size is 6291456, the size of data is 7690800` error. + +### Where are the backed up files stored when I use `local` storage? + +> **Note:** +> +> If no Network File System (NFS) is mounted to a BR or TiKV node, or if you use external storage that supports Amazon S3, GCS, or Azure Blob Storage protocols, the data backed up by BR is generated at each TiKV node.**Note that this is not the recommended way to deploy BR**, because the backup data are scattered in the local file system of each node. Collecting the backup data might result in data redundancy and operation and maintenance problems. Meanwhile, if you restore data directly before collecting the backup data, you will encounter the `SST file not found` error. + +When you use local storage, `backupmeta` is generated on the node where BR is running, and backup files are generated on the Leader nodes of each Region. + +### What should I do if the error message `could not read local://...:download sst failed` is returned during data restore? + +When you restore data, each node must have access to **all** backup files (SST files). By default, if `local` storage is used, you cannot restore data because the backup files are scattered among different nodes. Therefore, you have to copy the backup file of each TiKV node to the other TiKV nodes. **It is recommended that you store backup data to Amazon S3, Google Cloud Storage (GCS), Azure Blob Storage, or NFS**. + +### What should I do to handle the `Permission denied` or `No such file or directory` error, even if I have tried to run `br` using root in vain? + +You need to confirm whether TiKV has access to the backup directory. To back up data, confirm whether TiKV has the write permission. To restore data, confirm whether it has the read permission. + +During the backup operation, if the storage medium is the local disk or a network file system (NFS), make sure that the user to start `br` and the user to start TiKV are consistent (if `br` and TiKV are on different machines, the users' UIDs must be consistent). Otherwise, the `Permission denied` issue might occur. + +Running `br` as the `root` user might fail due to the disk permission, because the backup files (SST files) are saved by TiKV. + +> **Note:** +> +> You might encounter the same problem during data restore. When the SST files are read for the first time, the read permission is verified. The execution duration of DDL suggests that there might be a long interval between checking the permission and running `br`. You might receive the error message `Permission denied` after waiting for a long time. + +Therefore, it is recommended to check the permission before data restore according to the following steps: + +1. Run the Linux command for process query: + + {{< copyable "shell-regular" >}} + + ```bash + ps aux | grep tikv-server + ``` + + The output is as follows: + + ```shell + tidb_ouo 9235 10.9 3.8 2019248 622776 ? Ssl 08:28 1:12 bin/tikv-server --addr 0.0.0.0:20162 --advertise-addr 172.16.6.118:20162 --status-addr 0.0.0.0:20188 --advertise-status-addr 172.16.6.118:20188 --pd 172.16.6.118:2379 --data-dir /home/user1/tidb-data/tikv-20162 --config conf/tikv.toml --log-file /home/user1/tidb-deploy/tikv-20162/log/tikv.log + tidb_ouo 9236 9.8 3.8 2048940 631136 ? Ssl 08:28 1:05 bin/tikv-server --addr 0.0.0.0:20161 --advertise-addr 172.16.6.118:20161 --status-addr 0.0.0.0:20189 --advertise-status-addr 172.16.6.118:20189 --pd 172.16.6.118:2379 --data-dir /home/user1/tidb-data/tikv-20161 --config conf/tikv.toml --log-file /home/user1/tidb-deploy/tikv-20161/log/tikv.log + ``` + + Or you can run the following command: + + {{< copyable "shell-regular" >}} + + ```bash + ps aux | grep tikv-server | awk '{print $1}' + ``` + + The output is as follows: + + ```shell + tidb_ouo + tidb_ouo + ``` + +2. Query the startup information of the cluster using the `tiup` command: + + {{< copyable "shell-regular" >}} + + ```bash + tiup cluster list + ``` + + The output is as follows: + + ```shell + [root@Copy-of-VM-EE-CentOS76-v1 br]# tiup cluster list + Starting component `cluster`: /root/.tiup/components/cluster/v1.5.2/tiup-cluster list + Name User Version Path PrivateKey + ---- ---- ------- ---- ---------- + tidb_cluster tidb_ouo v5.0.2 /root/.tiup/storage/cluster/clusters/tidb_cluster /root/.tiup/storage/cluster/clusters/tidb_cluster/ssh/id_rsa + ``` + +3. Check the permission for the backup directory. For example, `backup` is for backup data storage: + + {{< copyable "shell-regular" >}} + + ```bash + ls -al backup + ``` + + The output is as follows: + + ```shell + [root@Copy-of-VM-EE-CentOS76-v1 user1]# ls -al backup + total 0 + drwxr-xr-x 2 root root 6 Jun 28 17:48 . + drwxr-xr-x 11 root root 310 Jul 4 10:35 .. + ``` + + From the output of step 2, you can find that the `tikv-server` instance is started by the user `tidb_ouo`. But the user `tidb_ouo` does not have the write permission for `backup`. Therefore, the backup fails. + +### Why are tables in the `mysql` schema not restored? + +Starting from BR v5.1.0, when you perform a full backup, BR backs up the **tables in the `mysql` schema**. Before BR v6.2.0, under default configuration, BR only restores user data, but does not restore tables in the **`mysql` schema**. + +To restore a table created by the user in the `mysql` schema (not system tables), you can explicitly include the table using [table filters](/table-filter.md#syntax). The following example shows how to restore the `mysql.usertable` table when BR performs a normal restore. + +{{< copyable "shell-regular" >}} + +```shell +br restore full -f '*.*' -f '!mysql.*' -f 'mysql.usertable' -s $external_storage_url --with-sys-table +``` + +In the preceding command, + +- `-f '*.*'` is used to override the default rules +- `-f '!mysql.*'` instructs BR not to restore tables in `mysql` unless otherwise stated. +- `-f 'mysql.usertable'` indicates that `mysql.usertable` should be restored. + +If you only need to restore `mysql.usertable`, run the following command: + +{{< copyable "shell-regular" >}} + +```shell +br restore full -f 'mysql.usertable' -s $external_storage_url --with-sys-table +``` + +Note that even if you configures [table filter](/table-filter.md#syntax), **BR does not restore the following system tables**: + +- Statistics tables (`mysql.stat_*`). But statistics can be restored. See [Back up statistics](/br/br-snapshot-manual.md#back-up-statistics). +- System variable tables (`mysql.tidb`, `mysql.global_variables`) +- [Other system tables](https://github.com/pingcap/tidb/blob/master/br/pkg/restore/snap_client/systable_restore.go#L31) + +### How to deal with the error of `cannot find rewrite rule` during restoration? + +Examine whether there are tables in the restoration cluster sharing the same name as other tables in the backup data but having inconsistent structures. In most cases, this issue is caused by missing indexes in the tables of the restoration cluster. A recommended approach is to delete such tables in the restoration cluster first and then retry restoration. + +## Other things you may want to know about backup and restore + +### What is the size of the backup data? Are there replicas of the backup? + +During data backup, backup files are generated on the Leader nodes of each Region. The size of the backup is equal to the data size, with no redundant replicas. Therefore, the total data size is approximately the total number of TiKV data divided by the number of replicas. + +However, if you want to restore data from local storage, the number of replicas is equal to that of the TiKV nodes, because each TiKV must have access to all backup files. + +### Why is the disk usage shown on the monitoring node inconsistent after backup or restore using BR? + +This inconsistency is caused by the fact that the data compression rate used in backup is different from the default rate used in restore. If the checksum succeeds, you can ignore this issue. + +### After BR restores the backup data, do I need to execute the `ANALYZE` statement on the table to update the statistics of TiDB on the tables and indexes? + +BR does not back up statistics (except in v4.0.9). Therefore, after restoring the backup data, you need to manually execute `ANALYZE TABLE` or wait for TiDB to automatically execute `ANALYZE`. + +In v4.0.9, BR backs up statistics by default, which consumes too much memory. To ensure that the backup process goes well, the backup for statistics is disabled by default starting from v4.0.10. + +If you do not execute `ANALYZE` on the table, TiDB will fail to select the optimal execution plan due to inaccurate statistics. If query performance is not a key concern, you can ignore `ANALYZE`. + +### Can I start multiple restore tasks at the same time to restore the data of a single cluster? + +**It is strongly not recommended** to start multiple restore tasks at the same time to restore the data of a single cluster for the following reasons: + +- When BR restores data, it modifies some global configurations of PD. Therefore, if you start multiple restore tasks for data restore at the same time, these configurations might be mistakenly overwritten and cause abnormal cluster status. +- BR consumes a lot of cluster resources to restore data, so in fact, running restore tasks in parallel improves the restore speed only to a limited extent. +- There has been no test for running multiple restore tasks in parallel for data restore, so it is not guaranteed to succeed. + +### Does BR back up the `SHARD_ROW_ID_BITS` and `PRE_SPLIT_REGIONS` information of a table? Does the restored table have multiple Regions? + +Yes. BR backs up the [`SHARD_ROW_ID_BITS` and `PRE_SPLIT_REGIONS`](/sql-statements/sql-statement-split-region.md#pre_split_regions) information of a table. The data of the restored table is also split into multiple Regions. + +## If the recovery process is interrupted, is it necessary to delete the already recovered data and start the recovery again? + +No, it is not necessary. Starting from v7.1.0, BR supports resuming data from a breakpoint. If the recovery is interrupted due to unexpected circumstances, simply restart the recovery task, and it will resume from where it left off. + +## After the recovery is complete, can I delete a specific table and then recover it again? + +Yes, after deleting a specific table, you can recover it again. But note that, you can only recover tables that are deleted using the `DROP TABLE` or `TRUNCATE TABLE` statement, not the `DELETE FROM` statement. This is because `DELETE FROM` only updates the MVCC version to mark the data to be deleted, and the actual data deletion occurs after GC. + +### Why does BR take a lot of memory when restoring statistics information? + +Before v7.6.0, the statistics data backed up by BR is stored together with the table information and loaded into memory during recovery. Therefore, when the backup statistics data is very large, BR needs to occupy a large amount of memory. + +Starting from v7.6.0, the backup statistics is stored in a specific file separately. BR does not load statistic data of any table until BR starts to restore the table, which saves memory. diff --git a/faq/migration-tidb-faq.md b/faq/migration-tidb-faq.md index 4218aecb6bba4..2a350f90e3931 100644 --- a/faq/migration-tidb-faq.md +++ b/faq/migration-tidb-faq.md @@ -146,7 +146,7 @@ The total read capacity has no limit. You can increase the read capacity by addi ### The error message `transaction too large` is displayed -Due to the limitation of the underlying storage engine, each key-value entry (one row) in TiDB should be no more than 6MB. You can adjust the [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50) configuration value up to 120MB. +Due to the limitation of the underlying storage engine, each key-value entry (one row) in TiDB should be no more than 6MB. You can adjust the [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500) configuration value up to 120MB. Distributed transactions need two-phase commit and the bottom layer performs the Raft replication. If a transaction is very large, the commit process would be quite slow and the write conflict is more likely to occur. Moreover, the rollback of a failed transaction leads to an unnecessary performance penalty. To avoid these problems, we limit the total size of key-value entries to no more than 100MB in a transaction by default. If you need larger transactions, modify the value of `txn-total-size-limit` in the TiDB configuration file. The maximum value of this configuration item is up to 10G. The actual limitation is also affected by the physical memory of the machine. diff --git a/releases/release-6.1.1.md b/releases/release-6.1.1.md index ba9f2c499d617..892c56a29737b 100644 --- a/releases/release-6.1.1.md +++ b/releases/release-6.1.1.md @@ -151,16 +151,16 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.1/quick-start-with- + TiCDC - - Fix the wrong maximum compatible version number [#6039](https://github.com/pingcap/tiflow/issues/6039) @[hi-rustin](https://github.com/hi-rustin) + - Fix the wrong maximum compatible version number [#6039](https://github.com/pingcap/tiflow/issues/6039) @[hi-rustin](https://github.com/Rustin170506) - Fix a bug that may cause the cdc server to panic when it receives an HTTP request before it fully starts [#5639](https://github.com/pingcap/tiflow/issues/5639) @[asddongmen](https://github.com/asddongmen) - Fix the ddl sink panic issue when the changefeed sync-point is enabled [#4934](https://github.com/pingcap/tiflow/issues/4934) @[asddongmen](https://github.com/asddongmen) - Fix the issue that a changefeed is stuck in some scenarios when sync-point is enabled [#6827](https://github.com/pingcap/tiflow/issues/6827) @[hicqu](https://github.com/hicqu) - Fix a bug that changefeed API does not work properly after the cdc server restarts [#5837](https://github.com/pingcap/tiflow/issues/5837) @[asddongmen](https://github.com/asddongmen) - Fix the data race issue in the black hole sink [#6206](https://github.com/pingcap/tiflow/issues/6206) @[asddongmen](https://github.com/asddongmen) - - Fix the TiCDC panic issue when you set `enable-old-value = false` [#6198](https://github.com/pingcap/tiflow/issues/6198) @[hi-rustin](https://github.com/hi-rustin) + - Fix the TiCDC panic issue when you set `enable-old-value = false` [#6198](https://github.com/pingcap/tiflow/issues/6198) @[hi-rustin](https://github.com/Rustin170506) - Fix the data consistency issue when the redo log feature is enabled [#6189](https://github.com/pingcap/tiflow/issues/6189) [#6368](https://github.com/pingcap/tiflow/issues/6368) [#6277](https://github.com/pingcap/tiflow/issues/6277) [#6456](https://github.com/pingcap/tiflow/issues/6456) [#6695](https://github.com/pingcap/tiflow/issues/6695) [#6764](https://github.com/pingcap/tiflow/issues/6764) [#6859](https://github.com/pingcap/tiflow/issues/6859) @[asddongmen](https://github.com/asddongmen) - Fix poor redo log performance by writing redo events asynchronously [#6011](https://github.com/pingcap/tiflow/issues/6011) @[CharlesCheung96](https://github.com/CharlesCheung96) - - Fix the issue that the MySQL sink cannot connect to IPv6 addresses [#6135](https://github.com/pingcap/tiflow/issues/6135) @[hi-rustin](https://github.com/hi-rustin) + - Fix the issue that the MySQL sink cannot connect to IPv6 addresses [#6135](https://github.com/pingcap/tiflow/issues/6135) @[hi-rustin](https://github.com/Rustin170506) + Backup & Restore (BR) diff --git a/releases/release-6.1.2.md b/releases/release-6.1.2.md index f63665f99b649..02b7ff7c5bad7 100644 --- a/releases/release-6.1.2.md +++ b/releases/release-6.1.2.md @@ -85,9 +85,9 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.1/quick-start-with- + TiCDC - Fix the issue that the cdc server might panic if it receives an HTTP request before the cdc server fully starts [#6838](https://github.com/pingcap/tiflow/issues/6838) @[asddongmen](https://github.com/asddongmen) - - Fix the log flooding issue during upgrade [#7235](https://github.com/pingcap/tiflow/issues/7235) @[hi-rustin](https://github.com/hi-rustin) - - Fix the issue that changefeed's redo log files might be deleted by mistake [#6413](https://github.com/pingcap/tiflow/issues/6413) @[hi-rustin](https://github.com/hi-rustin) - - Fix the issue that TiCDC might become unavailable when too many operations in an etcd transaction are committed [#7131](https://github.com/pingcap/tiflow/issues/7131) @[hi-rustin](https://github.com/hi-rustin) + - Fix the log flooding issue during upgrade [#7235](https://github.com/pingcap/tiflow/issues/7235) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that changefeed's redo log files might be deleted by mistake [#6413](https://github.com/pingcap/tiflow/issues/6413) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiCDC might become unavailable when too many operations in an etcd transaction are committed [#7131](https://github.com/pingcap/tiflow/issues/7131) @[hi-rustin](https://github.com/Rustin170506) - Fix the issue that data inconsistency might occur when non-reentrant DDL statements in redo logs are executed twice [#6927](https://github.com/pingcap/tiflow/issues/6927) @[hicqu](https://github.com/hicqu) + Backup & Restore (BR) diff --git a/releases/release-6.1.4.md b/releases/release-6.1.4.md index 4e452fbdbb06d..59dbf504d6981 100644 --- a/releases/release-6.1.4.md +++ b/releases/release-6.1.4.md @@ -77,7 +77,7 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.1/quick-start-with- - Fix the issue that `transaction_atomicity` and `protocol` cannot be updated via the configuration file [#7935](https://github.com/pingcap/tiflow/issues/7935) @[CharlesCheung96](https://github.com/CharlesCheung96) - Fix the issue that TiCDC mistakenly reports an error when the version of TiFlash is later than that of TiCDC [#7744](https://github.com/pingcap/tiflow/issues/7744) @[overvenus](https://github.com/overvenus) - Fix the issue that OOM occurs when TiCDC replicates large transactions [#7913](https://github.com/pingcap/tiflow/issues/7913) @[overvenus](https://github.com/overvenus) - - Fix a bug that the context deadline is exceeded when TiCDC replicates data without splitting large transactions [#7982](https://github.com/pingcap/tiflow/issues/7982) @[hi-rustin](https://github.com/hi-rustin) + - Fix a bug that the context deadline is exceeded when TiCDC replicates data without splitting large transactions [#7982](https://github.com/pingcap/tiflow/issues/7982) @[hi-rustin](https://github.com/Rustin170506) - Fix the issue that `sasl-password` in the `changefeed query` result is not masked [#7182](https://github.com/pingcap/tiflow/issues/7182) @[dveeden](https://github.com/dveeden) - Fix the issue that data is lost when a user quickly deletes a replication task and then creates another one with the same task name [#7657](https://github.com/pingcap/tiflow/issues/7657) @[overvenus](https://github.com/overvenus) diff --git a/releases/release-6.1.7.md b/releases/release-6.1.7.md index 2977b24b64f94..1ec99802e66d8 100644 --- a/releases/release-6.1.7.md +++ b/releases/release-6.1.7.md @@ -88,9 +88,9 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.1/quick-start-with- + TiCDC - - Fix the issue that TiCDC cannot create a changefeed with a downstream Kafka-on-Pulsar [#8892](https://github.com/pingcap/tiflow/issues/8892) @[hi-rustin](https://github.com/hi-rustin) + - Fix the issue that TiCDC cannot create a changefeed with a downstream Kafka-on-Pulsar [#8892](https://github.com/pingcap/tiflow/issues/8892) @[hi-rustin](https://github.com/Rustin170506) - Fix the issue that TiCDC cannot automatically recover when PD address or leader fails [#8812](https://github.com/pingcap/tiflow/issues/8812) [#8877](https://github.com/pingcap/tiflow/issues/8877) @[asddongmen](https://github.com/asddongmen) - - Fix the issue that when the downstream is Kafka, TiCDC queries the downstream metadata too frequently and causes excessive workload in the downstream [#8957](https://github.com/pingcap/tiflow/issues/8957) [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/hi-rustin) + - Fix the issue that when the downstream is Kafka, TiCDC queries the downstream metadata too frequently and causes excessive workload in the downstream [#8957](https://github.com/pingcap/tiflow/issues/8957) [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/Rustin170506) - Fix the issue that TiCDC gets stuck when PD fails such as network isolation or PD Owner node reboot [#8808](https://github.com/pingcap/tiflow/issues/8808) [#8812](https://github.com/pingcap/tiflow/issues/8812) [#8877](https://github.com/pingcap/tiflow/issues/8877) @[asddongmen](https://github.com/asddongmen) + TiDB Lightning diff --git a/releases/release-6.3.0.md b/releases/release-6.3.0.md new file mode 100644 index 0000000000000..f036afaa18a55 --- /dev/null +++ b/releases/release-6.3.0.md @@ -0,0 +1,450 @@ +--- +title: TiDB 6.3.0 Release Notes +summary: TiDB 6.3.0-DMR, released on September 30, 2022, introduces new features and improvements, including encryption at rest using the SM4 algorithm in TiKV, authentication using the SM3 algorithm in TiDB, and support for JSON data type and functions. It also provides execution time metrics at a finer granularity, enhances output for slow logs and `TRACE` statements, and supports deadlock history information in TiDB Dashboard. Additionally, TiDB v6.3.0 introduces new system variables and configuration file parameters, and fixes various bugs and issues. The release also includes improvements in TiKV, PD, TiFlash, Backup & Restore (BR), TiCDC, TiDB Binlog, TiDB Data Migration (DM), and TiDB Lightning. +--- + +# TiDB 6.3.0 Release Notes + +Release date: September 30, 2022 + +TiDB version: 6.3.0-DMR + +> **Note:** +> +> The TiDB 6.3.0-DMR documentation has been [archived](https://docs-archive.pingcap.com/tidb/v6.3/). PingCAP encourages you to use [the latest LTS version](https://docs.pingcap.com/tidb/stable) of the TiDB database. + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.3/quick-start-with-tidb) + +In v6.3.0-DMR, the key new features and improvements are as follows: + +- TiKV supports encryption at rest using the SM4 algorithm. +- TiDB supports authentication using the SM3 algorithm. +- The `CREATE USER` and `ALTER USER` statements support the `ACCOUNT LOCK/UNLOCK` option. +- JSON data type and functions become generally available (GA). +- TiDB supports null-aware anti join. +- TiDB provides execution time metrics at a finer granularity. +- A new syntactic sugar is added to simplify Range partition definitions. +- Range COLUMNS partitioning supports defining multiple columns. +- The performance of adding indexes is tripled. +- Reduce the impact of resource-consuming queries on the response time of lightweight queries by more than 50%. + +## New features + +### SQL + +* Add a new syntactic sugar (Range INTERVAL partitioning) to simplify Range partition definitions (experimental) [#35683](https://github.com/pingcap/tidb/issues/35683) @[mjonss](https://github.com/mjonss) + + TiDB provides [INTERVAL partitioning](/partitioned-table.md#range-interval-partitioning) as a new way of defining Range partitions. You do not need to enumerate all partitions, which drastically reduces the length of Range partitioning DDL statements. The syntax is equivalent to that of the original Range partitioning. + +* Range COLUMNS partitioning supports defining multiple columns [#36636](https://github.com/pingcap/tidb/issues/36636) @[mjonss](https://github.com/mjonss) + + TiDB supports [PARTITION BY RANGE COLUMNS (column_list)](/partitioned-table.md#range-columns-partitioning). `column_list` is no longer limited to a single column. The basic feature is the same as MySQL. + +* [EXCHANGE PARTITION](/partitioned-table.md#partition-management) becomes GA [#35996](https://github.com/pingcap/tidb/issues/35996) @[ymkzpx](https://github.com/ymkzpx) + +* Support pushdown of two more [window functions](/tiflash/tiflash-supported-pushdown-calculations.md) to TiFlash [#5579](https://github.com/pingcap/tiflash/issues/5579) @[SeaRise](https://github.com/SeaRise) + + * `LEAD()` + * `LAG()` + +* Provide lightweight metadata lock to improve the DML success rate during DDL change (experimental) [#37275](https://github.com/pingcap/tidb/issues/37275) @[wjhuang2016](https://github.com/wjhuang2016) + + TiDB uses the online asynchronous schema change algorithm to support changing metadata objects. When a transaction is executed, it obtains the corresponding metadata snapshot at the transaction start. If the metadata is changed during a transaction, to ensure data consistency, TiDB returns an `Information schema is changed` error and the transaction fails to commit. To solve the problem, TiDB v6.3.0 introduces [metadata lock](/metadata-lock.md) into the online DDL algorithm. To avoid DML errors whenever possible, TiDB coordinates the priority of DMLs and DDLs during table metadata change, and makes executing DDLs wait for the DMLs with old metadata to commit. + +* Improve the performance of adding indexes and reduce its impact on DML transactions (experimental) [#35983](https://github.com/pingcap/tidb/issues/35983) @[benjamin2037](https://github.com/benjamin2037) + + To improve the speed of backfilling when creating an index, TiDB v6.3.0 accelerates the `ADD INDEX` and `CREATE INDEX` DDL operations when the [`tidb_ddl_enable_fast_reorg`](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630) system variable is enabled. When the feature is enabled, the performance of adding indexes is about tripled. + +### Security + +* TiKV supports the SM4 algorithm for encryption at rest [#13041](https://github.com/tikv/tikv/issues/13041) @[jiayang-zheng](https://github.com/jiayang-zheng) + + Add the [SM4 algorithm](/encryption-at-rest.md) for TiKV encryption at rest. When you configure encryption at rest, you can enable the SM4 encryption capacity by setting the value of the `data-encryption-method` configuration to `sm4-ctr`. + +* TiDB supports authentication with the SM3 algorithm [#36192](https://github.com/pingcap/tidb/issues/36192) @[CbcWestwolf](https://github.com/CbcWestwolf) + + TiDB adds an authentication plugin [`tidb_sm3_password`](/security-compatibility-with-mysql.md) based on the SM3 algorithm. When this plugin is enabled, the user password is encrypted and validated using the SM3 algorithm. + +* TiDB JDBC supports authentication with the SM3 algorithm [#25](https://github.com/pingcap/mysql-connector-j/issues/25) @[lastincisor](https://github.com/lastincisor) + + Authenticating the user password needs client-side support. Now because [JDBC supports the SM3 algorithm](/develop/dev-guide-choose-driver-or-orm.md#java-drivers), you can connect to TiDB using SM3 authentication via TiDB-JDBC. + +### Observability + +* TiDB provides fine-grained metrics of SQL query execution time [#34106](https://github.com/pingcap/tidb/issues/34106) @[cfzjywxk](https://github.com/cfzjywxk) + + TiDB v6.3.0 provides fine-grained data metrics for [detailed observation of execution time](/latency-breakdown.md). Through the complete and segmented metrics, you can clearly understand the main time consumption of SQL queries, and then quickly find key problems and save time in troubleshooting. + +* Enhanced output for slow logs and `TRACE` statements [#34106](https://github.com/pingcap/tidb/issues/34106) @[cfzjywxk](https://github.com/cfzjywxk) + + TiDB v6.3.0 enhances the output of slow logs and `TRACE`. You can observe the [full-link duration](/latency-breakdown.md) of SQL queries from TiDB parsing to KV RocksDB writing to disk, which further enhances the diagnostic capabilities. + +* TiDB Dashboard provides deadlock history information [#34106](https://github.com/pingcap/tidb/issues/34106) @[cfzjywxk](https://github.com/cfzjywxk) + + From v6.3.0, TiDB Dashboard provides deadlock history. If you check the slow log in TiDB Dashboard and find the lock waiting time of some SQL statements to be excessively long, you can check the deadlock history to locate the root cause, which makes your diagnosis easier. + +### Performance + +* TiFlash changes the way of using FastScan (experimental) [#5252](https://github.com/pingcap/tiflash/issues/5252) @[hongyunyan](https://github.com/hongyunyan) + + In v6.2.0, TiFlash introduces the FastScan feature, which brings expected performance improvements but lacks flexibility in use. Therefore, in v6.3.0, TiFlash changes [the way of using FastScan](/tiflash/use-fastscan.md): the `ALTER TABLE ... SET TIFLASH MODE ...` syntax to enable or disable FastScan is deprecated. Instead, you can use the system variable [`tiflash_fastscan`](/system-variables.md#tiflash_fastscan-new-in-v630) to easily control whether to enable FastScan. + + When you upgrade from v6.2.0 to v6.3.0, all FastScan settings in v6.2.0 will become invalid, but will not affect the normal reading of data. You need to set the variable `tiflash_fastscan`. When you upgrade from v6.2.0 or an earlier version to v6.3.0, the FastScan feature is not enabled by default for all sessions to keep data consistency. + +* TiFlash optimizes data scanning performance in scenarios of multiple concurrency tasks [#5376](https://github.com/pingcap/tiflash/issues/5376) @[JinheLin](https://github.com/JinheLin) + + TiFlash reduces duplicate reads of the same data by combining read operations of the same data. It optimizes the resource overhead and [improves the performance of data scanning in the case of concurrent tasks](/tiflash/tiflash-configuration.md#configure-the-tiflashtoml-file). For multiple concurrent tasks, it avoids the situation where each task needs to read the same data separately, and avoids the possibility of multiple reads of the same data at the same time. + + This feature is experimental in v6.2.0, and becomes GA in v6.3.0. + +* TiFlash improves performance of data replication [#5237](https://github.com/pingcap/tiflash/issues/5237) @[breezewish](https://github.com/breezewish) + + TiFlash uses the Raft protocol for data replication from TiKV. Prior to v6.3.0, it often took a long time to replicate large amounts of replica data. TiDB v6.3.0 optimizes the TiFlash data replication mechanism and significantly improves the replication speed. When you use BR to recover data, use TiDB Lightning to import data, or add new TiFlash replicas, the TiFlash replicas can be replicated more quickly. You can query with TiFlash in a more timely manner. In addition, TiFlash replicas will also reach a secure and balanced state faster when you scale up, scale down, or modify the number of TiFlash replicas. + +* TiFlash supports three-stage aggregation of individual `COUNT(DISTINCT)` [#37202](https://github.com/pingcap/tidb/issues/37202) @[fixdb](https://github.com/fixdb) + + TiFlash supports rewriting queries containing only one `COUNT(DISTINCT)` into a [three-stage aggregation](/system-variables.md#tidb_opt_three_stage_distinct_agg-new-in-v630). This improves concurrency and performance. + +* TiKV supports log recycling [#214](https://github.com/tikv/raft-engine/issues/214) @[LykxSassinator](https://github.com/LykxSassinator) + + TiKV supports [recycling log files](/tikv-configuration-file.md#enable-log-recycle-new-in-v630) in Raft Engine. This reduces the long tail latency in network disks during Raft log appending and improves performance under write workloads. + +* TiDB supports null-aware anti join [#37525](https://github.com/pingcap/tidb/issues/37525) @[Arenatlx](https://github.com/Arenatlx) + + TiDB v6.3.0 introduces a new join type [Null-aware anti join (NAAJ)](/explain-subqueries.md#null-aware-anti-semi-join-not-in-and--all-subqueries). NAAJ can be aware of whether the collection is empty or `NULL` when processing collection operations. This optimizes the execution efficiency of operations such as `IN` and `= ANY` and improves SQL performance. + +* Add optimizer hints to control the build end of Hash Join [#35439](https://github.com/pingcap/tidb/issues/35439) @[Reminiscent](https://github.com/Reminiscent) + + In v6.3.0, the TiDB optimizer introduces 2 hints, `HASH_JOIN_BUILD()` and `HASH_JOIN_PROBE()`, to specify the Hash Join, its probe end, and its build end. When the optimizer fails to select the optimal execution plan, you can use these hints to intervene with the plan. + +* Support session-level common table expressions (CTE) inline [#36514](https://github.com/pingcap/tidb/issues/36514) @[elsa0520](https://github.com/elsa0520) + + TiDB v6.2.0 introduced the `MERGE` hint in optimizers to allow CTE inline, so that the consumers of a CTE query result can execute it in parallel in TiFlash. In v6.3.0, a session variable [`tidb_opt_force_inline_cte`](/system-variables.md#tidb_opt_force_inline_cte-new-in-v630) is introduced to allow CTE inline in sessions. This can greatly improve the ease of use. + +### Transactions + +* Support deferring checks of unique constraints in pessimistic transactions [#36579](https://github.com/pingcap/tidb/issues/36579) @[ekexium](https://github.com/ekexium) + + You can use the [`tidb_constraint_check_in_place_pessimistic`](/system-variables.md#tidb_constraint_check_in_place_pessimistic-new-in-v630) system variable to control when TiDB checks [unique constraints](/constraints.md#pessimistic-transactions) in pessimistic transactions. This variable is disabled by default. When the variable is enabled (set to `ON`), TiDB will defer locking operations and unique constraint checks in pessimistic transactions until necessary, thus improving the performance of bulk DML operations. + +* Optimize the way of fetching TSO in the Read-Committed isolation level [#36812](https://github.com/pingcap/tidb/issues/36812) @[TonsnakeLin](https://github.com/TonsnakeLin) + + In the Read-Committed isolation level, the system variable [`tidb_rc_write_check_ts`](/system-variables.md#tidb_rc_write_check_ts-new-in-v630) is introduced to control how TSO is fetched. In the case of Plan Cache hit, TiDB improves the execution efficiency of batch DML statements by reducing the frequency of fetching TSO, and reduces the execution time of running tasks in batch. + +### Stability + +* Reduce the impact of resource-consuming queries on the response time of lightweight queries [#13313](https://github.com/tikv/tikv/issues/13313) @[glorv](https://github.com/glorv) + + When resource-consuming queries and lightweight queries are executed at the same time, the response time of lightweight queries is affected. In this case, to ensure the quality of transactional services, lightweight queries are expected to be processed by TiDB first. In v6.3.0, TiKV optimizes the scheduling mechanism of read requests, so that the execution time of resource-consuming queries in each round can meet expectations. This drastically reduces the impact of resource-consuming queries on the response time of lightweight queries and reduces P99 latency by more than 50% for mixed workload scenarios. + +* Modify the default policy of loading statistics when statistics become outdated [#27601](https://github.com/pingcap/tidb/issues/27601) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + In v5.3.0, TiDB introduced the system variable [`tidb_enable_pseudo_for_outdated_stats`](/system-variables.md#tidb_enable_pseudo_for_outdated_stats-new-in-v530) to control how the optimizer behaves when the statistics become outdated. The default value is `ON`, which means keeping the behavior of the old version: When the statistics on objects that are involved in a SQL statement are outdated, the optimizer considers that statistics (other than the total number of rows on the table) are no longer reliable and uses pseudo statistics instead. After tests and analyses of actual user scenarios, the default value of `tidb_enable_pseudo_for_outdated_stats` is changed to `OFF` since v6.3.0. Even if the statistics become outdated, the optimizer will still use the statistics on the table, which makes the execution plan more stable. + +* Disabling Titan becomes GA @[tabokie](https://github.com/tabokie) + + You can [disable Titan](/storage-engine/titan-configuration.md#disable-titan) for online TiKV nodes. + +* Use `static` partition pruning when GlobalStats are not ready [#37535](https://github.com/pingcap/tidb/issues/37535) @[Yisaer](https://github.com/Yisaer) + + When [`dynamic pruning`](/partitioned-table.md#dynamic-pruning-mode) is enabled, the optimizer selects execution plans based on [GlobalStats](/statistics.md#collect-statistics-of-partitioned-tables-in-dynamic-pruning-mode). Before GlobalStats are fully collected, using pseudo statistics might cause performance regression. In v6.3.0, this issue is addressed by maintaining the `static` mode if you enable dynamic pruning before GlobalStats are collected. TiDB remains in the `static` mode until GlobalStats are collected. This ensures performance stability when you change the partition pruning settings. + +### Ease of use + +* Address the conflict between SQL-based data Placement Rules and TiFlash replicas [#37171](https://github.com/pingcap/tidb/issues/37171) @[lcwangchao](https://github.com/lcwangchao) + + TiDB v6.0.0 provides [SQL-based data Placement Rules](/placement-rules-in-sql.md). But this feature conflicts with TiFlash replicas due to implementation issues. TiDB v6.3.0 optimizes the implementation mechanisms, and resolves the conflict between SQL-based data Placement Rules and TiFlash. + +### MySQL compatibility + +* Improve MySQL 8.0 compatibility by adding support for four regular expression functions: `REGEXP_INSTR()`, `REGEXP_LIKE()`, `REGEXP_REPLACE()`, and `REGEXP_SUBSTR()` [#23881](https://github.com/pingcap/tidb/issues/23881) @[windtalker](https://github.com/windtalker) + + For more details about the compatibility with MySQL, see [Regular expression compatibility with MySQL](/functions-and-operators/string-functions.md#regular-expression-compatibility-with-mysql). + +* The `CREATE USER` and `ALTER USER` statements support the `ACCOUNT LOCK/UNLOCK` option [#37051](https://github.com/pingcap/tidb/issues/37051) @[CbcWestwolf](https://github.com/CbcWestwolf) + + When you create a user using the [`CREATE USER`](/sql-statements/sql-statement-create-user.md) statement, you can specify whether the created user is locked using the `ACCOUNT LOCK/UNLOCK` option. A locked user cannot log in to the database. + + You can modify the lock state of an existing user using the `ACCOUNT LOCK/UNLOCK` option in the [`ALTER USER`](/sql-statements/sql-statement-alter-user.md) statement. + +* JSON data type and JSON functions become GA [#36993](https://github.com/pingcap/tidb/issues/36993) @[xiongjiwei](https://github.com/xiongjiwei) + + JSON is a popular data format adopted by a large number of programs. TiDB has introduced the [JSON support](/data-type-json.md) as an experimental feature since an earlier version, compatible with MySQL's JSON data type and some JSON functions. + + In TiDB v6.3.0, the JSON data type and functions become GA, which enriches TiDB's data types, supports using JSON functions in [expression indexes](/sql-statements/sql-statement-create-index.md#expression-index) and [generated-columns](/generated-columns.md), and further improves TiDB's compatibility with MySQL. + +### Backup and restore + +* PITR supports [GCS and Azure Blob Storage](/br/backup-and-restore-storages.md) as backup storages @[joccau](https://github.com/joccau) + + If your TiDB cluster is deployed on Google Cloud or Azure, you can use the PITR feature after upgrading your cluster to v6.3.0. + +* BR supports AWS S3 Object Lock [#13442](https://github.com/tikv/tikv/issues/13442) @[3pointer](https://github.com/3pointer) + + You can protect backup data on AWS from being tampered with or deleted by enabling [S3 Object Lock](https://docs.aws.amazon.com/AmazonS3/latest/userguide/object-lock.html). + +### Data migration + +* TiDB Lightning supports [importing Parquet files exported by Apache Hive into TiDB](/tidb-lightning/tidb-lightning-data-source.md#parquet) [#37536](https://github.com/pingcap/tidb/issues/37536) @[buchuitoudegou](https://github.com/buchuitoudegou) + +* DM adds a new configuration item `safe-mode-duration` [#6224](https://github.com/pingcap/tiflow/issues/6224) @[okJiang](https://github.com/okJiang) + + This configuration item is added to the [task configuration file](/dm/task-configuration-file-full.md). You can adjust the automatic safe mode duration after DM exits abnormally. The default value is 60 seconds. If `safe-mode-duration` is set to `"0s"`, an error is reported when DM tries to enter safe mode after an abnormal restart. + +### TiDB data share subscription + +* TiCDC supports a deployment topology that can replicate data from multiple geo-distributed data sources [#5301](https://github.com/pingcap/tiflow/issues/5301) @[sdojjy](https://github.com/sdojjy) + + To support replicating data from a single TiDB cluster to multiple geo-distributed data systems, starting from v6.3.0, [you can deploy TiCDC in multiple IDCs](/ticdc/deploy-ticdc.md) to replicate data for each IDC. This feature helps deliver the capability of geo-distributed data replication and deployment topology. + +* TiCDC supports keeping the snapshots consistent between the upstream and the downstream (sync point) [#6977](https://github.com/pingcap/tiflow/issues/6977) @[asddongmen](https://github.com/asddongmen) + + In the scenarios of data replication for disaster recovery, TiCDC supports [periodically maintaining a downstream data snapshot](/ticdc/ticdc-upstream-downstream-check.md) so that the downstream snapshot is consistent with the upstream snapshot. With this feature, TiCDC can better support the scenarios where reads and writes are separate, and help you lower the cost. + +* TiCDC supports graceful upgrade [#4757](https://github.com/pingcap/tiflow/issues/4757) @[overvenus](https://github.com/overvenus) @[3AceShowHand](https://github.com/3AceShowHand) + + When TiCDC is deployed using [TiUP](/ticdc/deploy-ticdc.md#upgrade-cautions) (>=v1.11.0) or [TiDB Operator](https://docs.pingcap.com/tidb-in-kubernetes/v1.3/configure-a-tidb-cluster#configure-graceful-upgrade-for-ticdc-cluster) (>=v1.3.8), you can gracefully upgrade the TiCDC cluster. During the upgrade, data replication latency is kept as low as 30 seconds. This improves stability, empowering TiCDC to better support latency-sensitive applications. + +## Compatibility changes + +### System variables + +| Variable name | Change type | Description | +| --- | --- | --- | +| [`default_authentication_plugin`](/system-variables.md#default_authentication_plugin) | Modified | Adds a new option `tidb_sm3_password`. When this variable is set to `tidb_sm3_password`, SM3 is used as the encryption algorithm. | +| [`sql_require_primary_key`](/system-variables.md#sql_require_primary_key-new-in-v630) | Newly added | Controls whether to enforce the requirement that a table has a primary key. After this variable is enabled, attempting to create or alter a table without a primary key will produce an error. | +| [`tidb_adaptive_closest_read_threshold`](/system-variables.md#tidb_adaptive_closest_read_threshold-new-in-v630) | Newly added | Controls the threshold at which the TiDB server prefers to send read requests to the replica in the same region as the TiDB server when [`tidb_replica_read`](/system-variables.md#tidb_replica_read-new-in-v40) is set to `closest-adaptive`. | +| [`tidb_constraint_check_in_place_pessimistic`](/system-variables.md#tidb_constraint_check_in_place_pessimistic-new-in-v630) | Newly added | Controls when TiDB checks [unique constraints](/constraints.md#pessimistic-transactions) in pessimistic transactions. | +| [`tidb_ddl_disk_quota`](/system-variables.md#tidb_ddl_disk_quota-new-in-v630) | Newly added | Takes effect only when [`tidb_ddl_enable_fast_reorg`](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630) is enabled. It sets the usage limit of local storage during backfilling when creating an index. | +| [`tidb_ddl_enable_fast_reorg`](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630) | Newly added | Controls whether to enable the acceleration of `ADD INDEX` and `CREATE INDEX` DDL operations to improve the speed of backfilling when creating an index. | +| [`tidb_ddl_flashback_concurrency`](/system-variables.md#tidb_ddl_flashback_concurrency-new-in-v630) | Newly added | Controls the concurrency of `flashback cluster`. The feature controlled by this variable is not fully functional in TiDB v6.3.0. Do not change the default value. | +| [`tidb_enable_exchange_partition`](/system-variables.md#tidb_enable_exchange_partition) | Deprecated | Controls whether to enable the [`exchange partitions with tables`](/partitioned-table.md#partition-management) feature. The default value is `ON`, that is, `exchange partitions with tables` is enabled by default. | +| [`tidb_enable_foreign_key`](/system-variables.md#tidb_enable_foreign_key-new-in-v630) | Newly added | Controls whether to enable the `FOREIGN KEY` feature. The feature controlled by this variable is not fully functional in TiDB v6.3.0. Do not change the default value. | +| `tidb_enable_general_plan_cache` | Newly added | Controls whether to enable the General Plan Cache feature. The feature controlled by this variable is not fully functional in TiDB v6.3.0. Do not change the default value. | +| [`tidb_enable_metadata_lock`](/system-variables.md#tidb_enable_metadata_lock-new-in-v630)| Newly added | Specifies whether to enable the [Metadata lock](/metadata-lock.md) feature. | +| [`tidb_enable_null_aware_anti_join`](/system-variables.md#tidb_enable_null_aware_anti_join-new-in-v630) | Newly added | Controls whether TiDB applies Null-Aware Hash Join when Anti Join is generated by subqueries led by special set operators `NOT IN` and `!= ALL`. | +| [`tidb_enable_pseudo_for_outdated_stats`](/system-variables.md#tidb_enable_pseudo_for_outdated_stats-new-in-v530) | Modified | Controls the behavior of the optimizer on using statistics of a table when the statistics are outdated. The default value changes from `ON` to `OFF`, which means the optimizer still keeps using the statistics of the table even if the statistics of this table are outdated. | +| [`tidb_enable_rate_limit_action`](/system-variables.md#tidb_enable_rate_limit_action) | Modified | Controls whether to enable the dynamic memory control feature for the operator that reads data. When this variable is set to `ON`, the memory usage might not be under the control of [`tidb_mem_quota_query`](/system-variables.md#tidb_mem_quota_query). Therefore, the default value is changed from `ON` to `OFF`. | +| [`tidb_enable_tiflash_read_for_write_stmt`](/system-variables.md#tidb_enable_tiflash_read_for_write_stmt-new-in-v630) | Newly added | Controls whether read requests in SQL write statements are pushed down to TiFlash. The feature controlled by this variable is not fully functional in TiDB v6.3.0. Do not change the default value. | +| [`tidb_enable_unsafe_substitute`](/system-variables.md#tidb_enable_unsafe_substitute-new-in-v630) | Newly added | Controls whether to replace expressions with generated columns in an unsafe way. | +| `tidb_general_plan_cache_size` | Newly added | Controls the maximum number of execution plans that can be cached by General Plan Cache. The feature controlled by this variable is not fully functional in TiDB v6.3.0. Do not change the default value. | +| [`tidb_last_plan_replayer_token`](/system-variables.md#tidb_enable_unsafe_substitute-new-in-v630) | Newly added | Read-only and used to obtain the result of the last `PLAN REPLAYER DUMP` execution in the current session. | +| [tidb_max_paging_size](/system-variables.md#tidb_max_paging_size-new-in-v630) | Newly added | This variable is used to set the minimum number of rows during the coprocessor paging request process. | +| [`tidb_opt_force_inline_cte`](/system-variables.md#tidb_opt_force_inline_cte-new-in-v630) | Newly added | Controls whether common table expressions (CTEs) in the entire session are inlined or not. The default value is `OFF`, which means that inlining CTE is not enforced by default. | +| [`tidb_opt_three_stage_distinct_agg`](/system-variables.md#tidb_opt_three_stage_distinct_agg-new-in-v630) | Newly added | Specifies whether to rewrite a `COUNT(DISTINCT)` aggregation into a three-stage aggregation in MPP mode. The default value is `ON`. | +| [`tidb_partition_prune_mode`](/system-variables.md#tidb_partition_prune_mode-new-in-v51) | Modified | Specifies whether to enable dynamic pruning. Since v6.3.0, the default value changes to `dynamic`. | +| [`tidb_rc_read_check_ts`](/system-variables.md#tidb_rc_read_check_ts-new-in-v600) | Modified | Used for optimizing the timestamp acquisition, which is suitable for scenarios with read-committed isolation level where read-write conflicts are rare. This feature is oriented to specific service workloads and might cause performance regression in other scenarios. For this reason, since v6.3.0, the scope of this variable changes from `GLOBAL \| SESSION` to `INSTANCE`. That means you can enable this feature for specific TiDB instances. | +| [`tidb_rc_write_check_ts`](/system-variables.md#tidb_rc_write_check_ts-new-in-v630) | Newly added | Used for optimizing the acquisition of timestamps and is suitable for scenarios with few point-write conflicts in RC isolation level of pessimistic transactions. Enabling this variable can avoid the latency and overhead brought by obtaining the global timestamps during the execution of point-write statements | +| [`tiflash_fastscan`](/system-variables.md#tiflash_fastscan-new-in-v630) | Newly added | Controls whether to enable FastScan. If [FastScan](/tiflash/use-fastscan.md) is enabled (set to `ON`), TiFlash provides more efficient query performance, but does not guarantee the accuracy of the query results or data consistency. | + +### Configuration file parameters + +| Configuration file | Configuration | Change type | Description | +| --- | --- | --- | --- | +| TiDB | [`temp-dir`](/tidb-configuration-file.md#temp-dir-new-in-v630) | Newly added | Specifies the file system location used by TiDB to store temporary data. If a feature requires local storage in TiDB nodes, TiDB stores the corresponding temporary data in this location. The default value is `/tmp/tidb`. | +| TiKV | [`auto-adjust-pool-size`](/tikv-configuration-file.md#auto-adjust-pool-size-new-in-v630) | Newly added | Controls whether to automatically adjust the thread pool size. When it is enabled, the read performance of TiKV is optimized by automatically adjusting the UnifyReadPool thread pool size based on the current CPU usage.| +| TiKV | [`data-encryption-method`](/tikv-configuration-file.md#data-encryption-method) | Modified | Introduces a new value option `sm4-ctr`. When this configuration item is set to `sm4-ctr`, data is encrypted using SM4 before being stored. | +| TiKV | [`enable-log-recycle`](/tikv-configuration-file.md#enable-log-recycle-new-in-v630) | Newly added | Determines whether to recycle stale log files in Raft Engine. When it is enabled, logically purged log files will be reserved for recycling. This reduces the long tail latency on write workloads. This configuration item is only available when [format-version](/tikv-configuration-file.md#format-version-new-in-v630) is >= 2. | +| TiKV | [`format-version`](/tikv-configuration-file.md#format-version-new-in-v630) | Newly added | Specifies the version of log files in Raft Engine. The default log file version is `1` for TiKV earlier than v6.3.0. The log files can be read by TiKV >= v6.1.0. The default log file version is `2` for TiKV v6.3.0 and later. TiKV v6.3.0 and later can read the log files. | +| TiKV | [`log-backup.enable`](/tikv-configuration-file.md#enable-new-in-v620) | Modified | Since v6.3.0, the default value changes from `false` to `true`. | +| TiKV | [`log-backup.max-flush-interval`](/tikv-configuration-file.md#max-flush-interval-new-in-v620) | Modified | Since v6.3.0, the default value changes from `5min` to `3min`. | +| PD | [enable-diagnostic](/pd-configuration-file.md#enable-diagnostic-new-in-v630) | Newly added | Controls whether to enable the diagnostic feature. The default value is `false`. | +| TiFlash | [`dt_enable_read_thread`](/tiflash/tiflash-configuration.md#configure-the-tiflash-learnertoml-file) | Deprecated | Since v6.3.0, this configuration item is deprecated. The thread pool is used to handle read requests from the storage engine by default and cannot be disabled. | +| DM | [`safe-mode-duration`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Specifies the duration of the automatic safe mode. | +| TiCDC | [`enable-sync-point`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | Specifies whether to enable the Syncpoint feature. | +| TiCDC | [`sync-point-interval`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | Specifies the interval at which Syncpoint aligns the upstream and downstream snapshots. | +| TiCDC | [`sync-point-retention`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | Specifies how long the data is retained by Syncpoint in the downstream table. When this duration is exceeded, the data is cleaned up. | +| TiCDC | [`sink-uri.memory`](/ticdc/ticdc-changefeed-config.md#changefeed-cli-parameters) | Deprecated | The `memory` sorting is deprecated. It is not recommended to use it in any situation. | + +### Others + +* Log backup supports GCS and Azure Blob Storage as backup storage. +* Log backup is now compatible with the `exchange partition` DDL. +* The SQL statement `ALTER TABLE ...SET TiFLASH MODE ...` previously used for enabling [fastscan](/tiflash/use-fastscan.md) is deprecated, and replaced by the system variable [`tiflash_fastscan`](/system-variables.md#tiflash_fastscan-new-in-v630). When you upgrade from v6.2.0 to v6.3.0, all FastScan settings in v6.2.0 will become invalid, but will not affect the normal reading of data. In this case, you need to configure the variable [`tiflash_fastscan`](/system-variables.md#tiflash_fastscan-new-in-v630) to enable or disable FastScan. When you upgrade from an earlier version to v6.3.0, the FastScan feature is not enabled by default for all sessions to keep data consistent. +* To deploy TiFlash under the Linux AMD64 architecture, the CPU must support the AVX2 instruction set. Ensure that `grep avx2 /proc/cpuinfo` has output. To deploy TiFlash under the Linux ARM64 architecture, the CPU must support the ARMv8 instruction set architecture. Ensure that `grep 'crc32' /proc/cpuinfo | grep 'asimd'` has output. By using the instruction set extensions, TiFlash's vectorization engine can deliver better performance. +* The minimum version of HAProxy that works with TiDB is now v1.5. HAProxy versions between v1.5 and v2.1 now require the `post-41` configuration option to be set in `mysql-check`. It is recommended to use HAProxy v2.2 or newer. + +## Removed feature + +Since v6.3.0, TiCDC no longer supports configuring Pulsar sink. [kop](https://github.com/streamnative/kop) provided by StreamNative can be used as an alternative. + +## Improvements + ++ TiDB + + - TiDB is now case-insensitive to the target table name when checking the table existence [#34610](https://github.com/pingcap/tidb/issues/34610) @[tiancaiamao](https://github.com/tiancaiamao) + - Improve MySQL compatibility by adding a parsing check when setting the value of `init_connect` [#35324](https://github.com/pingcap/tidb/issues/35324) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Improve the log warning generated for new connections [#34964](https://github.com/pingcap/tidb/issues/34964) @[xiongjiwei](https://github.com/xiongjiwei) + - Optimize the HTTP API for querying DDL history jobs, and add support for the `start_job_id` parameter [#35838](https://github.com/pingcap/tidb/issues/35838) @[tiancaiamao](https://github.com/tiancaiamao) + - Report errors when the JSON path has wrong syntax [#22525](https://github.com/pingcap/tidb/issues/22525) [#34959](https://github.com/pingcap/tidb/issues/34959) @[xiongjiwei](https://github.com/xiongjiwei) + - Improve the performance of Join operations by fixing a false sharing issue [#37641](https://github.com/pingcap/tidb/issues/37641) @[gengliqi](https://github.com/gengliqi) + - Support exporting the execution plan information of multiple SQL statements at a time using [`PLAN REPLAYER`](/sql-plan-replayer.md), which makes troubleshooting more efficient [#37798](https://github.com/pingcap/tidb/issues/37798) @[Yisaer](https://github.com/Yisaer) + ++ TiKV + + - Support configuring the `unreachable_backoff` item to avoid Raftstore broadcasting too many messages after one peer becomes unreachable [#13054](https://github.com/tikv/tikv/issues/13054) @[5kbpers](https://github.com/5kbpers) + - Improve the fault tolerance of TSO service [#12794](https://github.com/tikv/tikv/issues/12794) @[pingyu](https://github.com/pingyu) + - Support dynamically modifying the number of sub-compaction operations performed concurrently in RocksDB (`rocksdb.max-sub-compactions`) [#13145](https://github.com/tikv/tikv/issues/13145) @[ethercflow](https://github.com/ethercflow) + - Optimize the performance of merging empty Regions [#12421](https://github.com/tikv/tikv/issues/12421) @[tabokie](https://github.com/tabokie) + - Support more regular expression functions [#13483](https://github.com/tikv/tikv/issues/13483) @[gengliqi](https://github.com/gengliqi) + - Support automatically adjusting the thread pool size based on the CPU usage [#13313](https://github.com/tikv/tikv/issues/13313) @[glorv](https://github.com/glorv) + ++ PD + + - Improve the query of the TiKV IO MBps metric in TiDB Dashboard [#5366](https://github.com/tikv/pd/issues/5366) @[YiniXu9506](https://github.com/YiniXu9506) + - Modify the URL in TiDB Dashboard from `metrics` to `monitoring` [#5366](https://github.com/tikv/pd/issues/5366) @[YiniXu9506](https://github.com/YiniXu9506) + ++ TiFlash + + - Support pushing down the `elt` function to TiFlash [#5104](https://github.com/pingcap/tiflash/issues/5104) @[Willendless](https://github.com/Willendless) + - Support pushing down the `leftShift` function to TiFlash [#5099](https://github.com/pingcap/tiflash/issues/5099) @[AnnieoftheStars](https://github.com/AnnieoftheStars) + - Support pushing down the `castTimeAsDuration` function to TiFlash [#5306](https://github.com/pingcap/tiflash/issues/5306) @[AntiTopQuark](https://github.com/AntiTopQuark) + - Support pushing down the `HexIntArg/HexStrArg` function to TiFlash [#5107](https://github.com/pingcap/tiflash/issues/5107) @[YangKeao](https://github.com/YangKeao) + - Refactor TiFlash's interpreter, and support the new interpreter Planner [#4739](https://github.com/pingcap/tiflash/issues/4739) @[SeaRise](https://github.com/SeaRise) + - Improve the accuracy of memory tracker in TiFlash [#5609](https://github.com/pingcap/tiflash/issues/5609) @[bestwoody](https://github.com/bestwoody) + - Improve the performance of string columns with the `UTF8_BIN/ASCII_BIN/LATIN1_BIN/UTF8MB4_BIN` collations [#5294](https://github.com/pingcap/tiflash/issues/5294) @[solotzg](https://github.com/solotzg) + - Calculate the I/O throughput in background in ReadLimiter [#5401](https://github.com/pingcap/tiflash/issues/5401), [#5091](https://github.com/pingcap/tiflash/issues/5091) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + ++ Tools + + + Backup & Restore (BR) + + - PITR can merge small files generated in log backup, which greatly reduces the number of backup files [#13232](https://github.com/tikv/tikv/issues/13232) @[Leavrth](https://github.com/Leavrth) + - PITR supports automatically configuring the number of TiFlash replicas based on the upstream cluster configuration after the restoration [#37208](https://github.com/pingcap/tidb/issues/37208) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Improve TiCDC's compatibility with the concurrent DDL framework introduced in the upstream TiDB [#6506](https://github.com/pingcap/tiflow/issues/6506) @[lance6716](https://github.com/lance6716) + - Support logging `start ts` of DML statements when MySQL sink gets an error [#6460](https://github.com/pingcap/tiflow/issues/6460) @[overvenus](https://github.com/overvenus) + - Enhance the `api/v1/health` API to return a more accurate health state of a TiCDC cluster [#4757](https://github.com/pingcap/tiflow/issues/4757) @[overvenus](https://github.com/overvenus) + - Implement MQ sink and MySQL sink in the asynchronous mode to improve the sink throughput [#5928](https://github.com/pingcap/tiflow/issues/5928) @[hicqu](https://github.com/hicqu) @[hi-rustin](https://github.com/Rustin170506) + - Delete the deprecated pulsar sink [#7087](https://github.com/pingcap/tiflow/issues/7087) @[hi-rustin](https://github.com/Rustin170506) + - Improve replication performance by discarding DDL statements that are irrelevant to a changefeed [#6447](https://github.com/pingcap/tiflow/issues/6447) @[asddongmen](https://github.com/asddongmen) + + + TiDB Data Migration (DM) + + - Improve compatibility with MySQL 8.0 as data source [#6448](https://github.com/pingcap/tiflow/issues/6448) @[lance6716](https://github.com/lance6716) + - Optimize DDL by executing DDL asynchronously when encounter "invalid connection" [#4689](https://github.com/pingcap/tiflow/issues/4689) @[lyzx2001](https://github.com/lyzx2001) + + + TiDB Lightning + + - Add query parameters for S3 external storage URL to support accessing the S3 data in another account by assuming a given role [#36891](https://github.com/pingcap/tidb/issues/36891) @[dsdashun](https://github.com/dsdashun) + +## Bug fixes + ++ TiDB + + - Fix the issue that the privilege check is skipped for `PREPARE` statements [#35784](https://github.com/pingcap/tidb/issues/35784) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the system variable `tidb_enable_noop_variable` can be set to `WARN` [#36647](https://github.com/pingcap/tidb/issues/36647) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that when an expression index is defined, the `ORDINAL_POSITION` column of the `INFORMATION_SCHEMA.COLUMNS` table might be incorrect [#31200](https://github.com/pingcap/tidb/issues/31200) @[bb7133](https://github.com/bb7133) + - Fix the issue that TiDB does not report an error when the timestamp is larger than `MAXINT32` [#31585](https://github.com/pingcap/tidb/issues/31585) @[bb7133](https://github.com/bb7133) + - Fix the issue that TiDB server cannot be started when the enterprise plugin is used [#37319](https://github.com/pingcap/tidb/issues/37319) @[xhebox](https://github.com/xhebox) + - Fix the incorrect output of `SHOW CREATE PLACEMENT POLICY` [#37526](https://github.com/pingcap/tidb/issues/37526) @[xhebox](https://github.com/xhebox) + - Fix the unexpected `EXCHANGE PARTITION` behaviors with temporary tables [#37201](https://github.com/pingcap/tidb/issues/37201) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that querying `INFORMATION_SCHEMA.TIKV_REGION_STATUS` returns an incorrect result @[zimulala](https://github.com/zimulala) + - Fix the issue that the `EXPLAIN` query on views does not check privileges [#34326](https://github.com/pingcap/tidb/issues/34326) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that JSON `null` cannot be updated to `NULL` [#37852](https://github.com/pingcap/tidb/issues/37852) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `row_count` of DDL jobs is inaccurate [#25968](https://github.com/pingcap/tidb/issues/25968) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that `FLASHBACK TABLE` does not work properly [#37386](https://github.com/pingcap/tidb/issues/37386) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue of failing to handle `prepared` statement flags in the typical MySQL protocol [#36731](https://github.com/pingcap/tidb/issues/36731) @[dveeden](https://github.com/dveeden) + - Fix the issue of incorrect TiDB status that might appear on startup in some extreme cases [#36791](https://github.com/pingcap/tidb/issues/36791) @[xhebox](https://github.com/xhebox) + - Fix the issue that `INFORMATION_SCHEMA.VARIABLES_INFO` does not comply with security enhanced mode (SEM) [#37586](https://github.com/pingcap/tidb/issues/37586) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that casting string to string goes wrong in queries with `UNION` [#31678](https://github.com/pingcap/tidb/issues/31678) @[cbcwestwolf](https://github.com/cbcwestwolf) + - Fix the wrong result that occurs when enabling dynamic mode in partitioned tables for TiFlash [#37254](https://github.com/pingcap/tidb/issues/37254) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the cast and comparison between binary strings and JSON in TiDB are incompatible with MySQL [#31918](https://github.com/pingcap/tidb/issues/31918) [#25053](https://github.com/pingcap/tidb/issues/25053) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `JSON_OBJECTAGG` and `JSON_ARRAYAGG` in TiDB are not compatible with MySQL on binary values [#25053](https://github.com/pingcap/tidb/issues/25053) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the comparison between JSON opaque values causes panic [#37315](https://github.com/pingcap/tidb/issues/37315) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the single precision float cannot be used in JSON aggregation functions [#37287](https://github.com/pingcap/tidb/issues/37287) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the `UNION` operator might return unexpected empty result [#36903](https://github.com/pingcap/tidb/issues/36903) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the result of the `castRealAsTime` expression is inconsistent with MySQL [#37462](https://github.com/pingcap/tidb/issues/37462) @[mengxin9014](https://github.com/mengxin9014) + - Fix the issue that pessimistic DML operations lock non-unique index keys [#36235](https://github.com/pingcap/tidb/issues/36235) @[ekexium](https://github.com/ekexium) + - Fix the issue that `auto-commit` change affects transaction commit behaviours [#36581](https://github.com/pingcap/tidb/issues/36581) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that the `EXPLAIN ANALYZE` statement with DML executors might return result before the transaction commit finishes [#37373](https://github.com/pingcap/tidb/issues/37373) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that the UPDATE statements incorrectly eliminate the projection in some cases, which causes the `Can't find column` error [#37568](https://github.com/pingcap/tidb/issues/37568) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the Join Reorder operation will mistakenly push down its Outer Join condition [#37238](https://github.com/pingcap/tidb/issues/37238) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the `IN` and `NOT IN` subqueries in some patterns report the `Can't find column` error [#37032](https://github.com/pingcap/tidb/issues/37032) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `Can't find column` is reported if an `UPDATE` statement contains common table expressions (CTE) [#35758](https://github.com/pingcap/tidb/issues/35758) @[AilinKid](https://github.com/AilinKid) + - Fix incorrect `PromQL` [#35856](https://github.com/pingcap/tidb/issues/35856) @[Defined2014](https://github.com/Defined2014) + ++ TiKV + + - Fix the issue that PD does not reconnect to TiKV after the Region heartbeat is interrupted [#12934](https://github.com/tikv/tikv/issues/12934) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that Regions might be overlapped if Raftstore is busy [#13160](https://github.com/tikv/tikv/issues/13160) @[5kbpers](https://github.com/5kbpers) + - Fix the issue that the PD client might cause deadlocks [#13191](https://github.com/tikv/tikv/issues/13191) @[bufferflies](https://github.com/bufferflies) [#12933](https://github.com/tikv/tikv/issues/12933) @[BurtonQin](https://github.com/BurtonQin) + - Fix the issue that TiKV might panic when encryption is disabled [#13081](https://github.com/tikv/tikv/issues/13081) @[jiayang-zheng](https://github.com/jiayang-zheng) + - Fix the wrong expression of `Unified Read Pool CPU` in Dashboard [#13086](https://github.com/tikv/tikv/issues/13086) @[glorv](https://github.com/glorv) + - Fix the issue that the TiKV service is unavailable for several minutes when a TiKV instance is in an isolated network environment [#12966](https://github.com/tikv/tikv/issues/12966) @[cosven](https://github.com/cosven) + - Fix the issue that TiKV mistakenly reports a `PessimisticLockNotFound` error [#13425](https://github.com/tikv/tikv/issues/13425) @[sticnarf](https://github.com/sticnarf) + - Fix the issue that PITR might cause data loss in some situations [#13281](https://github.com/tikv/tikv/issues/13281) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that causes checkpoint not advanced when there are some long pessimistic transactions [#13304](https://github.com/tikv/tikv/issues/13304) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV does not distinguish the datetime type (`DATETIME`, `DATE`, `TIMESTAMP` and `TIME`) and `STRING` type in JSON [#13417](https://github.com/tikv/tikv/issues/13417) @[YangKeao](https://github.com/YangKeao) + - Fix incompatibility with MySQL of comparison between JSON bool and other JSON value [#13386](https://github.com/tikv/tikv/issues/13386) [#37481](https://github.com/pingcap/tidb/issues/37481) @[YangKeao](https://github.com/YangKeao) + ++ PD + + - Fix PD panics caused by the issue that gRPC handles errors inappropriately when `enable-forwarding` is enabled [#5373](https://github.com/tikv/pd/issues/5373) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that unhealthy Region might cause PD panic [#5491](https://github.com/tikv/pd/issues/5491) @[nolouch](https://github.com/nolouch) + - Fix the issue that the TiFlash learner replica might not be created [#5401](https://github.com/tikv/pd/issues/5401) @[HunDunDM](https://github.com/HunDunDM) + ++ TiFlash + + - Fix the issue that a window function might cause TiFlash to crash when the query is canceled [#5814](https://github.com/pingcap/tiflash/issues/5814) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that wrong data input for `CAST(value AS DATETIME)` causing high TiFlash sys CPU [#5097](https://github.com/pingcap/tiflash/issues/5097) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that the result of `CAST(Real/Decimal AS time)` is inconsistent with MySQL [#3779](https://github.com/pingcap/tiflash/issues/3779) @[mengxin9014](https://github.com/mengxin9014) + - Fix the issue that some obsolete data in storage cannot be deleted [#5570](https://github.com/pingcap/tiflash/issues/5570) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that page GC might block creating tables [#5697](https://github.com/pingcap/tiflash/issues/5697) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the panic that occurs after creating the primary index with a column containing the `NULL` value [#5859](https://github.com/pingcap/tiflash/issues/5859) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that might cause the information of the checkpoint being stale [#36423](https://github.com/pingcap/tidb/issues/36423) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the regions are not balanced because the concurrency is set too large during the restoration [#37549](https://github.com/pingcap/tidb/issues/37549) @[3pointer](https://github.com/3pointer) + - Fix the issue that might cause log backup checkpoint TS stuck when TiCDC exists in the cluster [#37822](https://github.com/pingcap/tidb/issues/37822) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that might lead to backup and restoration failure if special characters exist in the authorization key of external storage [#37469](https://github.com/pingcap/tidb/issues/37469) @[MoCuishle28](https://github.com/MoCuishle28) + + + TiCDC + + - Fix the issue that TiCDC returns an inaccurate error for a wrong PD address with a grpc service [#6458](https://github.com/pingcap/tiflow/issues/6458) @[crelax](https://github.com/crelax) + - Fix the issue that the `cdc cause cli changefeed list` command does not return failed changefeeds [#6334](https://github.com/pingcap/tiflow/issues/6334) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that TiCDC is unavailable when changefeed initialization fails [#6859](https://github.com/pingcap/tiflow/issues/6859) @[asddongmen](https://github.com/asddongmen) + + + TiDB Binlog + + - Fix the issue that Drainer cannot send requests correctly to Pump when compressor is set to gzip [#1152](https://github.com/pingcap/tidb-binlog/issues/1152) @[lichunzhu](https://github.com/lichunzhu) + + + TiDB Data Migration (DM) + + - Fix the issue that DM reports the `Specified key was too long` error [#5315](https://github.com/pingcap/tiflow/issues/5315) @[lance6716](https://github.com/lance6716) + - Fix goroutine leak when relay meets an error [#6193](https://github.com/pingcap/tiflow/issues/6193) @[lance6716](https://github.com/lance6716) + - Fix the issue that when `collation_compatible` is set to `"strict"`, DM might generate SQL with duplicated collations [#6832](https://github.com/pingcap/tiflow/issues/6832) @[lance6716](https://github.com/lance6716) + - Reduce the appearance of the warning message "found error when get timezone from binlog status_vars" in DM-worker log [#6628](https://github.com/pingcap/tiflow/issues/6628) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that latin1 data might be corrupted during replication [#7028](https://github.com/pingcap/tiflow/issues/7028) @[lance6716](https://github.com/lance6716) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning does not support columns starting with slash, number, or non-ascii characters in Parquet files [#36980](https://github.com/pingcap/tidb/issues/36980) @[D3Hunter](https://github.com/D3Hunter) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- @[An-DJ](https://github.com/An-DJ) +- @[AnnieoftheStars](https://github.com/AnnieoftheStars) +- @[AntiTopQuark](https://github.com/AntiTopQuark) +- @[blacktear23](https://github.com/blacktear23) +- @[BurtonQin](https://github.com/BurtonQin) (First-time contributor) +- @[crelax](https://github.com/crelax) +- @[eltociear](https://github.com/eltociear) +- @[fuzhe1989](https://github.com/fuzhe1989) +- @[erwadba](https://github.com/erwadba) +- @[jianzhiyao](https://github.com/jianzhiyao) +- @[joycse06](https://github.com/joycse06) +- @[morgo](https://github.com/morgo) +- @[onlyacat](https://github.com/onlyacat) +- @[peakji](https://github.com/peakji) +- @[rzrymiak](https://github.com/rzrymiak) +- @[tisonkun](https://github.com/tisonkun) +- @[whitekeepwork](https://github.com/whitekeepwork) +- @[Ziy1-Tan](https://github.com/Ziy1-Tan) diff --git a/releases/release-6.4.0.md b/releases/release-6.4.0.md new file mode 100644 index 0000000000000..08fce00ba076f --- /dev/null +++ b/releases/release-6.4.0.md @@ -0,0 +1,486 @@ +--- +title: TiDB 6.4.0 Release Notes +summary: TiDB 6.4.0-DMR introduces new features and improvements, including support for restoring a cluster to a specific point in time, compatibility with Linear Hash partitioning syntax, and a high-performance `AUTO_INCREMENT` mode. It also enhances fault recovery, memory usage control, and statistics collection. TiFlash now supports the SM4 algorithm for encryption at rest, and TiCDC supports replicating data to Kafka. The release also includes bug fixes and improvements across various tools and components. +--- + +# TiDB 6.4.0 Release Notes + +Release date: November 17, 2022 + +TiDB version: 6.4.0-DMR + +> **Note:** +> +> The TiDB 6.4.0-DMR documentation has been [archived](https://docs-archive.pingcap.com/tidb/v6.4/). PingCAP encourages you to use [the latest LTS version](https://docs.pingcap.com/tidb/stable) of the TiDB database. + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.4/quick-start-with-tidb) + +In v6.4.0-DMR, the key new features and improvements are as follows: + +- Support restoring a cluster to a specific point in time by using [`FLASHBACK CLUSTER TO TIMESTAMP`](/sql-statements/sql-statement-flashback-cluster.md) (experimental). +- Support [tracking the global memory usage](/configure-memory-usage.md) of TiDB instances (experimental). +- Be compatible with [the Linear Hash partitioning syntax](/partitioned-table.md#how-tidb-handles-linear-hash-partitions). +- Support a high-performance and globally monotonic [`AUTO_INCREMENT`](/auto-increment.md#mysql-compatibility-mode) (experimental). +- Support range selection of array data in [the JSON type](/data-type-json.md). +- Accelerate fault recovery in extreme situations such as disk failures and stuck I/O. +- Add the [dynamic planning algorithm](/join-reorder.md#example-the-dynamic-programming-algorithm-of-join-reorder) to determine table join order. +- Introduce [a new optimizer hint `NO_DECORRELATE`](/optimizer-hints.md#no_decorrelate) to control whether to perform decorrelation for correlated subqueries. +- The [cluster diagnostics](/dashboard/dashboard-diagnostics-access.md) feature becomes GA. +- TiFlash supports the SM4 algorithm for [encryption at rest](/encryption-at-rest.md#tiflash). +- Support using a SQL statement to [compact TiFlash replicas of specified partitions in a table immediately](/sql-statements/sql-statement-alter-table-compact.md#compact-tiflash-replicas-of-specified-partitions-in-a-table). +- Support [backing up a TiDB cluster using EBS volume snapshots](https://docs.pingcap.com/tidb-in-kubernetes/v1.4/backup-to-aws-s3-by-snapshot). +- DM supports [writing upstream data source information to the extended columns of the downstream merged table](/dm/dm-table-routing.md#extract-table-schema-and-source-information-and-write-into-the-merged-table). + +## New features + +### SQL + +* Support using a SQL statement to compact TiFlash replicas of specified partitions in a table immediately [#5315](https://github.com/pingcap/tiflash/issues/5315) @[hehechen](https://github.com/hehechen) + + Since v6.2.0, TiDB has supported the feature of [compacting physical data immediately](/sql-statements/sql-statement-alter-table-compact.md#alter-table--compact) on a full-table replica of TiFlash. You can choose the right time to manually execute SQL statements to immediately compact the physical data in TiFlash, which helps to reduce storage space and improve query performance. In v6.4.0, we refine the granularity of TiFlash replica data to be compacted and support compacting TiFlash replicas of specified partitions in a table immediately. + + By executing the SQL statement `ALTER TABLE table_name COMPACT [PARTITION PartitionNameList] [engine_type REPLICA]`, you can immediately compact TiFlash replicas of specified partitions in a table. + + For more information, see [User document](/sql-statements/sql-statement-alter-table-compact.md#compact-tiflash-replicas-of-specified-partitions-in-a-table). + +* Support restoring a cluster to a specific point in time by using `FLASHBACK CLUSTER TO TIMESTAMP` (experimental) [#37197](https://github.com/pingcap/tidb/issues/37197) [#13303](https://github.com/tikv/tikv/issues/13303) @[Defined2014](https://github.com/Defined2014) @[bb7133](https://github.com/bb7133) @[JmPotato](https://github.com/JmPotato) @[Connor1996](https://github.com/Connor1996) @[HuSharp](https://github.com/HuSharp) @[CalvinNeo](https://github.com/CalvinNeo) + + You can use the `FLASHBACK CLUSTER TO TIMESTAMP` syntax to restore a cluster to a specific point in time quickly within the Garbage Collection (GC) lifetime. This feature helps you to easily and quickly undo DML misoperations. For example, you can use this syntax to restore the original cluster in minutes after mistakenly executing `DELETE` without a `WHERE` clause. This feature does not rely on database backups and supports rolling back data at different time points to determine the exact time when data changes. Note that `FLASHBACK CLUSTER TO TIMESTAMP` cannot replace database backups. + + Before executing `FLASHBACK CLUSTER TO TIMESTAMP`, you need to pause PITR and replication tasks running on such tools as TiCDC and restart them after the `FLASHBACK` is completed. Otherwise, replication tasks might fail. + + For more information, see [User document](/sql-statements/sql-statement-flashback-cluster.md). + +* Support restoring a deleted database by using `FLASHBACK DATABASE` [#20463](https://github.com/pingcap/tidb/issues/20463) @[erwadba](https://github.com/erwadba) + + By using `FLASHBACK DATABASE`, you can restore a database and its data deleted by `DROP` within the garbage collection (GC) life time. This feature does not depend on any external tools. You can quickly restore data and metadata using SQL statements. + + For more information, see [User document](/sql-statements/sql-statement-flashback-database.md). + +### Security + +* TiFlash supports the SM4 algorithm for encryption at rest [#5953](https://github.com/pingcap/tiflash/issues/5953) @[lidezhu](https://github.com/lidezhu) + + Add the SM4 algorithm for TiFlash encryption at rest. When you configure encryption at rest, you can enable the SM4 encryption capacity by setting the value of the `data-encryption-method` configuration to `sm4-ctr` in the `tiflash-learner.toml` configuration file. + + For more information, see [User document](/encryption-at-rest.md#tiflash). + +### Observability + +* Cluster diagnostics becomes GA [#1438](https://github.com/pingcap/tidb-dashboard/issues/1438) @[Hawkson-jee](https://github.com/Hawkson-jee) + + The [cluster diagnostics](/dashboard/dashboard-diagnostics-access.md) feature in TiDB Dashboard diagnoses the problems that might exist in a cluster within a specified time range, and summarizes the diagnostic results and the cluster-related load monitoring information into [a diagnostic report](/dashboard/dashboard-diagnostics-report.md). This diagnostic report is in the form of a web page. You can browse the page offline and circulate this page link after saving the page from a browser. + + With the diagnostic reports, you can quickly understand the basic health information of the cluster, including the load, component status, time consumption, and configurations. If the cluster has some common problems, you can locate the causes in the result of the built-in automatic diagnosis in the [diagnostic information](/dashboard/dashboard-diagnostics-report.md#diagnostic-information) section. + +### Performance + +* Introduce the concurrency adaptive mechanism for coprocessor tasks [#37724](https://github.com/pingcap/tidb/issues/37724) @[you06](https://github.com/you06) + + As the number of coprocessor tasks increases, based on TiKV's processing speed, TiDB automatically increases concurrency (adjust the value of [`tidb_distsql_scan_concurrency`](/system-variables.md#tidb_distsql_scan_concurrency)) to reduce the coprocessor task queue and thus reduce latency. + +* Add the dynamic planning algorithm to determine table join order [#37825](https://github.com/pingcap/tidb/issues/37825) @[winoros](https://github.com/winoros) + + In earlier versions, TiDB uses the greedy algorithm to determine the join order of tables. In v6.4.0, the TiDB optimizer introduces the [dynamic planning algorithm](/join-reorder.md#example-the-dynamic-programming-algorithm-of-join-reorder). The dynamic planning algorithm can enumerate more possible join orders than the greedy algorithm, so it increases the possibility to find a better execution plan and improves SQL execution efficiency in some scenarios. + + Because the dynamic programming algorithm consumes more time, the selection of the TiDB Join Reorder algorithms is controlled by the [`tidb_opt_join_reorder_threshold`](/system-variables.md#tidb_opt_join_reorder_threshold) variable. If the number of nodes participating in Join Reorder is greater than this threshold, TiDB uses the greedy algorithm. Otherwise, TiDB uses the dynamic programming algorithm. + + For more information, see [User document](/join-reorder.md). + +* The prefix index supports filtering null values. [#21145](https://github.com/pingcap/tidb/issues/21145) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + This feature is an optimization for the prefix index. When a column in a table has a prefix index, the `IS NULL` or `IS NOT NULL` condition of the column in the SQL statement can be directly filtered by the prefix, which avoids table lookup in this case and improves the performance of the SQL execution. + + For more information, see [User document](/system-variables.md#tidb_opt_prefix_index_single_scan-new-in-v640). + +* Enhance the TiDB chunk reuse mechanism [#38606](https://github.com/pingcap/tidb/issues/38606) @[keeplearning20221](https://github.com/keeplearning20221) + + In earlier versions, TiDB only reuses chunks in the `writechunk` function. TiDB v6.4.0 extends the chunk reuse mechanism to operators in Executor. By reusing chunks, TiDB does not need to frequently request memory release and SQL queries are executed more efficiently in some scenarios. You can use the system variable [`tidb_enable_reuse_chunk`](/system-variables.md#tidb_enable_reuse_chunk-new-in-v640) to control whether to reuse chunk objects, which is enabled by default. + + For more information, see [User document](/system-variables.md#tidb_enable_reuse_chunk-new-in-v640). + +* Introduce a new optimizer hint `NO_DECORRELATE` to control whether to perform decorrelation for correlated subqueries [#37789](https://github.com/pingcap/tidb/issues/37789) @[time-and-fate](https://github.com/time-and-fate) + + By default, TiDB always tries to rewrite correlated subqueries to perform decorrelation, which usually improves execution efficiency. However, in some scenarios, decorrelation reduces the execution efficiency. In v6.4.0, TiDB introduces the optimizer hint `NO_DECORRELATE` to tell the optimizer not to perform decorrelation for specified query blocks to improve query performance in some scenarios. + + For more information, see [User document](/optimizer-hints.md#no_decorrelate). + +* Improve the performance of statistics collection on partitioned tables [#37977](https://github.com/pingcap/tidb/issues/37977) @[Yisaer](https://github.com/Yisaer) + + In v6.4.0, TiDB optimizes the strategy of collecting statistics on partitioned tables. You can use the system variable [`tidb_auto_analyze_partition_batch_size`](/system-variables.md#tidb_auto_analyze_partition_batch_size-new-in-v640) to set the concurrency of collecting statistics on partitioned tables in parallel to speed up the collection and shorten the analysis time. + +### Stability + +* Accelerate fault recovery in extreme situations such as disk failures and stuck I/O [#13648](https://github.com/tikv/tikv/issues/13648) @[LykxSassinator](https://github.com/LykxSassinator) + + For enterprise users, database availability is one of the most important metrics. While in complex hardware environments, how to quickly detect and recover from failures has always been one of the challenges of database availability. In v6.4.0, TiDB fully optimizes the state detection mechanism of TiKV nodes. Even in extreme situations such as disk failures and stuck I/O, TiDB can still report node state quickly and use the active wake-up mechanism to launch Leader election in advance, which accelerates cluster self-healing. Through this optimization, TiDB can shorten the cluster recovery time by about 50% in the case of disk failures. + +* Global control on TiDB memory usage [#37816](https://github.com/pingcap/tidb/issues/37816) @[wshwsh12](https://github.com/wshwsh12) + + In v6.4.0, TiDB introduces global control of memory usage as an experimental feature that tracks the global memory usage of TiDB instances. You can use the system variable [`tidb_server_memory_limit`](/system-variables.md#tidb_server_memory_limit-new-in-v640) to set the upper limit for the global memory usage. When the memory usage reaches the threshold, TiDB tries to reclaim and release more free memory. When the memory usage exceeds the threshold, TiDB identifies and cancels the SQL operation that has the highest memory usage to avoid system issues caused by excessive memory usage. + + When the memory consumption of TiDB instances has potential risks, TiDB will collect diagnostic information in advance and write it to the specified directory to facilitate the issue diagnosis. At the same time, TiDB provides system table views [`INFORMATION_SCHEMA.MEMORY_USAGE`](/information-schema/information-schema-memory-usage.md) and [`INFORMATION_SCHEMA.MEMORY_USAGE_OPS_HISTORY`](/information-schema/information-schema-memory-usage-ops-history.md) that show the memory usage and operation history to help you better understand the memory usage. + + Global memory control is a milestone in TiDB memory management. It introduces a global view for instances and adopts systematic management for memory, which can greatly enhance database stability and service availability in more key scenarios. + + For more information, see [User document](/configure-memory-usage.md). + +* Control the memory usage of the range-building optimizer [#37176](https://github.com/pingcap/tidb/issues/37176) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + In v6.4.0, the system variable [`tidb_opt_range_max_size`](/system-variables.md#tidb_opt_range_max_size-new-in-v640) is introduced to limit the maximum memory usage of the optimizer that builds ranges. When the memory usage exceeds the limit, the optimizer will build more coarse-grained ranges instead of more exact ranges to reduce memory consumption. If a SQL statement has many `IN` conditions, this optimization can significantly reduce the memory usage of compiling and ensure system stability. + + For more information, see [User document](/system-variables.md#tidb_opt_range_max_size-new-in-v640). + +* Support synchronously loading statistics (GA) [#37434](https://github.com/pingcap/tidb/issues/37434) @[chrysan](https://github.com/chrysan) + + TiDB v6.4.0 enables the synchronously loading statistics feature by default. This feature allows TiDB to synchronously load large-sized statistics (such as histograms, TopN, and Count-Min Sketch statistics) into memory when you execute SQL statements, which improves the completeness of statistics for SQL optimization. + + For more information, see [User document](/system-variables.md#tidb_stats_load_sync_wait-new-in-v540). + +* Reduce the impact of batch write requests on the response time of lightweight transactional writes [#13313](https://github.com/tikv/tikv/issues/13313) @[glorv](https://github.com/glorv) + + The business logic of some systems requires periodic batch DML tasks, but processing these batch write tasks increases the latency of online transactions. In v6.3.0, TiKV optimizes the scheduling of read requests in hybrid workload scenarios, so you can enable the [`readpool.unified.auto-adjust-pool-size`](/tikv-configuration-file.md#auto-adjust-pool-size-new-in-v630) configuration item to have TiKV automatically adjust the size of the UnifyReadPool thread pool for all read requests. In v6.4.0, TiKV can dynamically identify and prioritize write requests as well, and control the maximum bytes that the Apply thread can write for one FSM (Finite-state Machine) in one round of poll, thus reducing the impact of batch write requests on the response time of transactional writes. + +### Ease of use + +* TiKV API V2 becomes generally available (GA) [#11745](https://github.com/tikv/tikv/issues/11745) @[pingyu](https://github.com/pingyu) + + Before v6.1.0, TiKV only provides basic Key Value read and write capability because it only stores the raw data passed in by the client. In addition, due to different coding methods and unscoped data ranges, TiDB, Transactional KV, and RawKV cannot be used at the same time in the same TiKV cluster; instead, multiple clusters are needed in this case, thus increasing machine and deployment costs. + + TiKV API V2 provides a new RawKV storage format and access interface, which delivers the following benefits: + + - Store data in MVCC with the change timestamp of the data recorded, based on which Change Data Capture (CDC) is implemented. This feature is experimental and is detailed in [TiKV-CDC](https://github.com/tikv/migration/blob/main/cdc/README.md). + - Data is scoped according to different usage and API V2 supports co-existence of TiDB, Transactional KV, and RawKV applications in a single cluster. + - Reserve the Key Space field to support features such as multi-tenancy. + + To enable TiKV API V2, set `api-version = 2` in the `[storage]` section of the TiKV configuration file. + + For more information, see [User document](/tikv-configuration-file.md#api-version-new-in-v610). + +* Improve the accuracy of TiFlash data replication progress [#4902](https://github.com/pingcap/tiflash/issues/4902) @[hehechen](https://github.com/hehechen) + + In TiDB, the `PROGRESS` field of the `INFORMATION_SCHEMA.TIFLASH_REPLICA` table is used to indicate the progress of data replication from the corresponding tables in TiKV to the TiFlash replicas. In earlier TiDB versions, the `PROCESS` field only provides the progress of data replication during the creation of the TiFlash replicas. After a TiFlash replica is created, if new data is imported to a corresponding table in TiKV, this field will not be updated to show the replication progress from TiKV to TiFlash for the new data. + + In v6.4.0, TiDB improves the update mechanism of data replication progress for TiFlash replicas. After a TiFlash replica is created, if new data is imported to a corresponding table in TiKV, the `PROGRESS` value in the [`INFORMATION_SCHEMA.TIFLASH_REPLICA`](/information-schema/information-schema-tiflash-replica.md) table will be updated to show the actual replication progress from TiKV to TiFlash for the new data. With this improvement, you can easily view the actual progress of TiFlash data replication. + + For more information, see [User document](/information-schema/information-schema-tiflash-replica.md). + +### MySQL compatibility + +* Be compatible with the Linear Hash partitioning syntax [#38450](https://github.com/pingcap/tidb/issues/38450) @[mjonss](https://github.com/mjonss) + + In the earlier version, TiDB has supported the Hash, Range, and List partitioning. Starting from v6.4.0, TiDB can also be compatible with the syntax of [MySQL Linear Hash partitioning](https://dev.mysql.com/doc/refman/5.7/en/partitioning-linear-hash.html). + + In TiDB, you can execute the existing DDL statements of your MySQL Linear Hash partitions directly, and TiDB will create the corresponding Hash partition tables (note that there is no Linear Hash partition inside TiDB). You can also execute the existing DML statements of your MySQL Linear Hash partitions directly, and TiDB will return the query result of the corresponding TiDB Hash partitions normally. This feature ensures the TiDB syntax compatibility with MySQL Linear Hash partitions and facilitates seamless migration from MySQL-based applications to TiDB. + + If the number of partitions is a power of 2, the rows in a TiDB Hash partitioned table are distributed the same as that in the MySQL Linear Hash partitioned table. Otherwise, the distribution of these rows in TiDB is different from MySQL. + + For more information, see [User document](/partitioned-table.md#how-tidb-handles-linear-hash-partitions). + +* Support a high-performance and globally monotonic `AUTO_INCREMENT` (experimental) [#38442](https://github.com/pingcap/tidb/issues/38442) @[tiancaiamao](https://github.com/tiancaiamao) + + TiDB v6.4.0 introduces the `AUTO_INCREMENT` MySQL compatibility mode. This mode introduces a centralized auto-increment ID allocating service that ensures IDs monotonically increase on all TiDB instances. This feature makes it easier to sort query results by auto-increment IDs. To use the MySQL compatibility mode, you need to set `AUTO_ID_CACHE` to `1` when creating a table. The following is an example: + + ```sql + CREATE TABLE t (a INT AUTO_INCREMENT PRIMARY KEY) AUTO_ID_CACHE = 1; + ``` + + For more information, see [User document](/auto-increment.md#mysql-compatibility-mode). + +* Support range selection of array data in the JSON type [#13644](https://github.com/tikv/tikv/issues/13644) @[YangKeao](https://github.com/YangKeao) + + Starting from v6.4.0, you can use the MySQL-compatible [range selection syntax](https://dev.mysql.com/doc/refman/8.0/en/json.html#json-paths) in TiDB. + + - With the keyword `to`, you can specify the start and end positions of array elements and select elements of a continuous range in an array. With `0`, you can specify the position of the first element in an array. For example, using `$[0 to 2]`, you can select the first three elements of an array. + + - With the keyword `last`, you can specify the position of the last element in an array, which allows you to set the position from right to left. For example, using `$[last-2 to last]`, you can select the last three elements of an array. + + This feature simplifies the process of writing SQL statements, further improves the JSON type compatibility, and reduces the difficulty of migrating MySQL applications to TiDB. + +* Support adding additional descriptions for database users [#38172](https://github.com/pingcap/tidb/issues/38172) @[CbcWestwolf](https://github.com/CbcWestwolf) + + In TiDB v6.4, you can use the [`CREATE USER`](/sql-statements/sql-statement-create-user.md) or [`ALTER USER`](/sql-statements/sql-statement-alter-user.md) to add additional descriptions for database users. TiDB provides two description formats. You can add a text comment using `COMMENT` and add a set of structured attributes in JSON format using `ATTRIBUTE`. + + In addition, TiDB v6.4.0 adds the [`USER_ATTRIBUTES`](/information-schema/information-schema-user-attributes.md) table, where you can view the information of user comments and user attributes. + + ```sql + CREATE USER 'newuser1'@'%' COMMENT 'This user is created only for test'; + CREATE USER 'newuser2'@'%' ATTRIBUTE '{"email": "user@pingcap.com"}'; + SELECT * FROM INFORMATION_SCHEMA.USER_ATTRIBUTES; + ``` + + ```sql + +-----------+------+---------------------------------------------------+ + | USER | HOST | ATTRIBUTE | + +-----------+------+---------------------------------------------------+ + | newuser1 | % | {"comment": "This user is created only for test"} | + | newuser1 | % | {"email": "user@pingcap.com"} | + +-----------+------+---------------------------------------------------+ + 2 rows in set (0.00 sec) + ``` + + This feature improves TiDB compatibility with MySQL syntax and makes it easier to integrate TiDB into tools or platforms in the MySQL ecosystem. + +### Backup and restore + +* Support backing up a TiDB cluster using EBS volume snapshots [#33849](https://github.com/pingcap/tidb/issues/33849) @[fengou1](https://github.com/fengou1) + + If your TiDB cluster is deployed on EKS and uses AWS EBS volumes, and you have the following requirements when backing up TiDB cluster data, you can use TiDB Operator to back up the data by volume snapshots and metadata to AWS S3: + + - Minimize the impact of backup, for example, to keep the impact on QPS and transaction latency less than 5%, and to occupy no cluster CPU and memory. + - Back up and restore data in a short time. For example, finish backup within 1 hour and restore data in 2 hours. + + For more information, see [User document](https://docs.pingcap.com/tidb-in-kubernetes/v1.4/backup-to-aws-s3-by-snapshot). + +### Data migration + +* DM supports writing upstream data source information to the extended columns of the downstream merged table [#37797](https://github.com/pingcap/tidb/issues/37797) @[lichunzhu](https://github.com/lichunzhu) + + When merging sharded schemas and tables from upstream to TiDB, you can manually add several fields (extended columns) in the target table and specify their values when configuring the DM task. For example, if you specify the names of the upstream sharded schema and table for the extended columns, the data written to the downstream by DM will include the schema name and table name. When the downstream data looks unusual, you can use this feature to quickly locate the data source information in the target table, such as the schema name and table name. + + For more information, see [Extract table, schema, and source information and write into the merged table](/dm/dm-table-routing.md#extract-table-schema-and-source-information-and-write-into-the-merged-table). + +* DM optimizes the pre-check mechanism by changing some mandatory check items to optional ones [#7333](https://github.com/pingcap/tiflow/issues/7333) @[lichunzhu](https://github.com/lichunzhu) + + To run a data migration task smoothly, DM triggers [a precheck](/dm/dm-precheck.md) automatically at the start of the task and returns the check results. DM starts the migration only after the precheck is passed. + + In v6.4.0, DM changes the following three check items from mandatory to optional, which improves the pass rate of the pre-check: + + - Check whether the upstream tables use character sets that are incompatible with TiDB. + - Check whether the upstream tables have primary key constraints or unique key constraints + - Check whether the database ID `server_id` for the upstream database has been specified in the primary-secondary configuration. + +* DM supports configuring binlog position and GTID as optional parameters for incremental migration tasks [#7393](https://github.com/pingcap/tiflow/issues/7393) @[GMHDBJD](https://github.com/GMHDBJD) + + Since v6.4.0, you can perform incremental migration directly without specifying the binlog position or GTID. DM automatically obtains the binlog files generated after the task starts from upstream and migrates these incremental data to the downstream. This relieves users from laborious understanding and complicated configuration. + + For more information, see [DM Advanced Task Configuration File](/dm/task-configuration-file-full.md). + +* DM adds more status indicators for migration tasks [#7343](https://github.com/pingcap/tiflow/issues/7343) @[okJiang](https://github.com/okJiang) + + In v6.4.0, DM adds more performance and progress indicators for migration tasks, which helps you understand the migration performance and progress more intuitively and provides you with a reference for troubleshooting. + + * Add status indicators (in bytes/s) showing data importing and exporting performance. + * Rename the performance indicator for writing data to the downstream database from TPS to RPS (in rows/s). + * Add progress indicators showing the data export progress of DM full migration tasks. + + For more information about these indicators, see [Query Task Status in TiDB Data Migration](/dm/dm-query-status.md). + +### TiDB data share subscription + +- TiCDC supports replicating data to Kafka of the `3.2.0` version [#7191](https://github.com/pingcap/tiflow/issues/7191) @[3AceShowHand](https://github.com/3AceShowHand) + + From v6.4.0, TiCDC supports [replicating data to Kafka](/replicate-data-to-kafka.md) of the `3.2.0` version and earlier. + +## Compatibility changes + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_constraint_check_in_place_pessimistic`](/system-variables.md#tidb_constraint_check_in_place_pessimistic-new-in-v630) | Modified | Removes the GLOBAL scope and allows you to modify the default value using the [`pessimistic-txn.constraint-check-in-place-pessimistic`](/tidb-configuration-file.md#constraint-check-in-place-pessimistic-new-in-v640) configuration item. This variable controls when TiDB checks the unique constraints in pessimistic transactions. | +| [`tidb_ddl_flashback_concurrency`](/system-variables.md#tidb_ddl_flashback_concurrency-new-in-v630) | Modified | Takes effect starting from v6.4.0 and controls the concurrency of [`FLASHBACK CLUSTER TO TIMESTAMP`](/sql-statements/sql-statement-flashback-cluster.md). The default value is `64`. | +| [`tidb_enable_clustered_index`](/system-variables.md#tidb_enable_clustered_index-new-in-v50) | Modified | Changes the default value from `INT_ONLY` to `ON`, meaning that primary keys are created as clustered indexes by default.| +| [`tidb_enable_paging`](/system-variables.md#tidb_enable_paging-new-in-v540) | Modified | Changes the default value from `OFF` to `ON`, meaning that the method of paging to send coprocessor requests is used by default. | +| [`tidb_enable_prepared_plan_cache`](/system-variables.md#tidb_enable_prepared_plan_cache-new-in-v610) | Modified | Adds the SESSION scope. This variable controls whether to enable [Prepared Plan Cache](/sql-prepared-plan-cache.md). | +| [`tidb_memory_usage_alarm_ratio`](/system-variables.md#tidb_memory_usage_alarm_ratio) | Modified | Changes the default value from `0.8` to `0.7`. This variable controls the memory usage ratio that triggers the tidb-server memory alarm. | +| [`tidb_opt_agg_push_down`](/system-variables.md#tidb_opt_agg_push_down) | Modified | Adds the GLOBAL scope. This variable controls whether the optimizer executes the optimization operation of pushing down the aggregate function to the position before Join, Projection, and UnionAll. | +| [`tidb_prepared_plan_cache_size`](/system-variables.md#tidb_prepared_plan_cache_size-new-in-v610) | Modified | Adds the SESSION scope. This variable controls the maximum number of plans that can be cached in a session. | +| [`tidb_stats_load_sync_wait`](/system-variables.md#tidb_stats_load_sync_wait-new-in-v540) | Modified | Changes the default value from `0` to `100`, meaning that the SQL execution can wait for at most 100 milliseconds by default to synchronously load complete column statistics. | +| [`tidb_stats_load_pseudo_timeout`](/system-variables.md#tidb_stats_load_pseudo_timeout-new-in-v540) | Modified | Changes the default value from `OFF` to `ON`, meaning that the SQL optimization gets back to using pseudo statistics after reaching the timeout of synchronously loading complete column statistics. | +| [`last_sql_use_alloc`](/system-variables.md#last_sql_use_alloc-new-in-v640) | Newly added | Shows whether the previous statement uses a cached chunk object (chunk allocation). This variable is read-only and the default value is `OFF`. | +| [`tidb_auto_analyze_partition_batch_size`](/system-variables.md#tidb_auto_analyze_partition_batch_size-new-in-v640) | Newly added | Specifies the number of partitions that TiDB can [automatically analyzes](/statistics.md#automatic-update) at a time when analyzing a partitioned table (which means automatically collecting statistics on a partitioned table). The default value is `1`.| +| [`tidb_enable_external_ts_read`](/system-variables.md#tidb_enable_external_ts_read-new-in-v640) | Newly added | Controls whether TiDB reads data with the timestamp specified by [`tidb_external_ts`](/system-variables.md#tidb_external_ts-new-in-v640). The default value is `OFF`. | +| [`tidb_enable_gogc_tuner`](/system-variables.md#tidb_enable_gogc_tuner-new-in-v640) | Newly added | Controls whether to enable GOGC Tuner. The default value is `ON`. | +| [`tidb_enable_reuse_chunk`](/system-variables.md#tidb_enable_reuse_chunk-new-in-v640) | Newly added | Controls whether TiDB enables chunk objects cache. The default value is `ON`, meaning that TiDB prefers to use the cached chunk object and only requests from the system if the requested object is not in the cache. If the value is `OFF`, TiDB requests chunk objects from the system directly. | +| [`tidb_enable_prepared_plan_cache_memory_monitor`](/system-variables.md#tidb_enable_prepared_plan_cache_memory_monitor-new-in-v640) | Newly added | Controls whether to count the memory consumed by the execution plans cached in the Prepared Plan Cache. The default value is `ON`.| +| [`tidb_external_ts`](/system-variables.md#tidb_external_ts-new-in-v640) | Newly added | The default value is `0`. If [`tidb_enable_external_ts_read`](/system-variables.md#tidb_enable_external_ts_read-new-in-v640) is set to `ON`, TiDB reads data with the timestamp specified by this variable.| +| [`tidb_gogc_tuner_threshold`](/system-variables.md#tidb_gogc_tuner_threshold-new-in-v640) | Newly added | Specifies the maximum memory threshold for tuning GOGC. When the memory exceeds this threshold, GOGC Tuner stops working. The default value is `0.6`. | +| [`tidb_memory_usage_alarm_keep_record_num`](/system-variables.md#tidb_memory_usage_alarm_keep_record_num-new-in-v640) | Newly added | When the tidb-server memory usage exceeds the memory alarm threshold and triggers an alarm, TiDB only retains the status files generated during the recent 5 alarms by default. You can adjust this number with this variable. | +| [`tidb_opt_prefix_index_single_scan`](/system-variables.md#tidb_opt_prefix_index_single_scan-new-in-v640) | Newly added | Controls whether the TiDB optimizer pushes down some filter conditions to the prefix index to avoid unnecessary table lookup and to improve query performance. The default value is `ON`. | +| [`tidb_opt_range_max_size`](/system-variables.md#tidb_opt_range_max_size-new-in-v640) | Newly added | Specifies the upper limit of memory usage for the optimizer to construct a scan range. The default value is `67108864` (64 MiB). | +| [`tidb_server_memory_limit`](/system-variables.md#tidb_server_memory_limit-new-in-v640) | Newly added | Controls the upper limit of memory usage for the optimizer to build scan ranges (experimental). The default value is `0`, meaning that there is no memory limit. | +| [`tidb_server_memory_limit_gc_trigger`](/system-variables.md#tidb_server_memory_limit_gc_trigger-new-in-v640) | Newly added | Controls the threshold at which TiDB tries to trigger GC (experimental). The default value is `70%`. | +| [`tidb_server_memory_limit_sess_min_size`](/system-variables.md#tidb_server_memory_limit_sess_min_size-new-in-v640) | Newly added | After you enable the memory limit, TiDB will terminate the SQL statement with the highest memory usage on the current instance. This variable specifies the minimum memory usage of the SQL statement to be terminated. The default value is `134217728` (128 MiB).| + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | `tidb_memory_usage_alarm_ratio` | Deleted | This configuration item is no longer effective. | +| TiDB | `memory-usage-alarm-ratio` | Deleted | Replaced by the system variable [`tidb_memory_usage_alarm_ratio`](/system-variables.md#tidb_memory_usage_alarm_ratio). If this configuration item has been configured in a TiDB version earlier than v6.4.0, it will not take effect after the upgrade. | +| TiDB | [`pessimistic-txn.constraint-check-in-place-pessimistic`](/tidb-configuration-file.md#constraint-check-in-place-pessimistic-new-in-v640) | Newly added | Controls the default value of the system variable [`tidb_constraint_check_in_place_pessimistic`](/system-variables.md#tidb_constraint_check_in_place_pessimistic-new-in-v630). The default value is `true`. | +| TiDB | [`tidb-max-reuse-chunk`](/tidb-configuration-file.md#tidb-max-reuse-chunk-new-in-v640) | Newly added | Controls the maximum cached chunk objects of chunk allocation. The default value is `64`.| +| TiDB | [`tidb-max-reuse-column`](/tidb-configuration-file.md#tidb-max-reuse-column-new-in-v640) | Newly added | Controls the maximum cached column objects of chunk allocation. The default value is `256`. | +| TiKV | [`cdc.raw-min-ts-outlier-threshold`](https://docs.pingcap.com/tidb/v6.2/tikv-configuration-file#raw-min-ts-outlier-threshold-new-in-v620) | Deprecated | This configuration item is no longer effective. | +| TiKV | [`causal-ts.alloc-ahead-buffer`](/tikv-configuration-file.md#alloc-ahead-buffer-new-in-v640) | Newly added | The pre-allocated TSO cache size (in duration). The default value is `3s`. | +| TiKV | [`causal-ts.renew-batch-max-size`](/tikv-configuration-file.md#renew-batch-max-size-new-in-v640)| Newly added | Controls the maximum number of TSOs in a timestamp request. The default value is `8192`. | +| TiKV | [`raftstore.apply-yield-write-size`](/tikv-configuration-file.md#apply-yield-write-size-new-in-v640) | Newly added | Controls the maximum number of bytes that the Apply thread can write for one FSM (Finite-state Machine) in one round of poll. The default value is `32KiB`. This is a soft limit. | +| PD | [`tso-update-physical-interval`](/pd-configuration-file.md#tso-update-physical-interval) | Newly added | Takes effect starting from v6.4.0 and controls the interval at which PD updates the physical time of TSO. The default value is `50ms`. | +| TiFlash | [`data-encryption-method`](/tiflash/tiflash-configuration.md#configure-the-tiflash-learnertoml-file) | Modified | Introduces a new value option `sm4-ctr`. When this configuration item is set to `sm4-ctr`, data is encrypted using SM4 before being stored. | +| DM | [`routes.route-rule-1.extract-table`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Optional. Used in the sharding scenario for extracting the source information of sharded tables. The extracted information will be written to the merged table in the downstream to identify the data source. If this parameter is configured, you need to manually create a merged table in the downstream in advance. | +| DM | [`routes.route-rule-1.extract-schema`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Optional. Used in the sharding scenario for extracting the source information of sharded schemas. The extracted information will be written to the merged table in the downstream to identify the data source. If this parameter is configured, you need to manually create a merged table in the downstream in advance. | +| DM | [`routes.route-rule-1.extract-source`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Optional. Used in the sharding scenario for extracting the source instance information. The extracted information will be written to the merged table in the downstream to identify the data source. If this parameter is configured, you need to manually create a merged table in the downstream in advance. | +| TiCDC | [`transaction-atomicity`](/ticdc/ticdc-sink-to-mysql.md#configure-sink-uri-for-mysql-or-tidb) | Modified | Changes the default value from `table` to `none`. This change helps reduce replication latency and OOM risks. In addition, TiCDC now only splits a few transactions (the size of a single transaction exceeds 1024 rows), instead of all transactions. | + +### Others + +- Starting from v6.4.0, the `mysql.user` table adds two new columns: `User_attributes` and `Token_issuer`. If you [restore system tables in the `mysql` schema](/br/br-snapshot-guide.md#restore-tables-in-the-mysql-schema) from backup data of earlier TiDB versions to TiDB v6.4.0, BR will report the `column count mismatch` error for the `mysql.user` table. If you do not restore system tables in the `mysql` schema, this error will not be reported. +- For files whose names match the [format of Dumpling exported files](/dumpling-overview.md#format-of-exported-files) but end with uncompressed formats (such as `test-schema-create.sql.origin` and `test.table-schema.sql.origin`), the way how TiDB Lightning handles them is changed. Before v6.4.0, if the files to be imported include such files, TiDB Lightning skips importing such files. Starting from v6.4.0, TiDB Lightning assumes that such files use unsupported compression formats, so the import task will fail. +- Starting with v6.4.0, only the changefeed with the `SYSTEM_VARIABLES_ADMIN` or `SUPER` privilege can use the TiCDC Syncpoint feature. + +## Improvements + ++ TiDB + + - Allow modifying the noop variable `lc_messages` [#38231](https://github.com/pingcap/tidb/issues/38231) @[djshow832](https://github.com/djshow832) + - Support the `AUTO_RANDOM` column as the first column of the clustered composite index [#38572](https://github.com/pingcap/tidb/issues/38572) @[tangenta](https://github.com/tangenta) + - Use pessimistic transactions in internal transaction retry to avoid retry failure and reduce time consumption [#38136](https://github.com/pingcap/tidb/issues/38136) @[jackysp](https://github.com/jackysp) + ++ TiKV + + - Add a new configuration item `apply-yield-write-size` to control the maximum number of bytes that the Apply thread can write for one Finite-state Machine in one round of poll, and relieve Raftstore congestion when the Apply thread writes a large volume of data [#13313](https://github.com/tikv/tikv/issues/13313) @[glorv](https://github.com/glorv) + - Warm up the entry cache before migrating the leader of Region to avoid QPS jitter during the leader transfer process [#13060](https://github.com/tikv/tikv/issues/13060) @[cosven](https://github.com/cosven) + - Support pushing down the `json_constrains` operator to Coprocessor [#13592](https://github.com/tikv/tikv/issues/13592) @[lizhenhuan](https://github.com/lizhenhuan) + - Add the asynchronous function for `CausalTsProvider` to improve the flush performance in some scenarios [#13428](https://github.com/tikv/tikv/issues/13428) @[zeminzhou](https://github.com/zeminzhou) + ++ PD + + - The v2 algorithm of the hot Region scheduler becomes GA. In some scenarios, the v2 algorithm can achieve better balancing in both configured dimensions and reduce invalid scheduling [#5021](https://github.com/tikv/pd/issues/5021) @[HundunDM](https://github.com/hundundm) + - Optimize the timeout mechanism of operator step to avoid premature timeout [#5596](https://github.com/tikv/pd/issues/5596) @[bufferflies](https://github.com/bufferflies) + - Improve the performance of the scheduler in large clusters [#5473](https://github.com/tikv/pd/issues/5473) @[bufferflies](https://github.com/bufferflies) + - Support using external timestamp which is not provided by PD [#5637](https://github.com/tikv/pd/issues/5637) @[lhy1024](https://github.com/lhy1024) + ++ TiFlash + + - Refactor the TiFlash MPP error handling logic to further improve the stability of MPP [#5095](https://github.com/pingcap/tiflash/issues/5095) @[windtalker](https://github.com/windtalker) + - Optimize the sorting of the TiFlash computation process, and optimize the key handling for Join and Aggregation [#5294](https://github.com/pingcap/tiflash/issues/5294) @[solotzg](https://github.com/solotzg) + - Optimize the memory usage for decoding and remove redundant transfer columns to improve Join performance [#6157](https://github.com/pingcap/tiflash/issues/6157) @[yibin87](https://github.com/yibin87) + ++ Tools + + + TiDB Dashboard + + - Support displaying TiFlash metrics on the Monitoring page and optimize the presentation of metrics on that page [#1440](https://github.com/pingcap/tidb-dashboard/issues/1440) @[YiniXu9506](https://github.com/YiniXu9506) + - Show the number of rows for results in the Slow Query list and SQL Statement list [#1443](https://github.com/pingcap/tidb-dashboard/issues/1443) @[baurine](https://github.com/baurine) + - Optimize the Dashboard to not report the Alertmanager errors when Alertmanager does not exist [#1444](https://github.com/pingcap/tidb-dashboard/issues/1444) @[baurine](https://github.com/baurine) + + + Backup & Restore (BR) + + - Improve the mechanism for loading the metadata. The metadata is loaded into memory only when necessary, which significantly reduces the memory usage during PITR [#38404](https://github.com/pingcap/tidb/issues/38404) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Support replicating the exchange partition DDL statements [#639](https://github.com/pingcap/tiflow/issues/639) @[asddongmen](https://github.com/asddongmen) + - Improve non-batch sending performance for the MQ sink module [#7353](https://github.com/pingcap/tiflow/issues/7353) @[hi-rustin](https://github.com/Rustin170506) + - Improve performance of TiCDC puller when a table has a large number of Regions [#7078](https://github.com/pingcap/tiflow/issues/7078) [#7281](https://github.com/pingcap/tiflow/issues/7281) @[sdojjy](https://github.com/sdojjy) + - Support reading historical data in the downstream TiDB by using the `tidb_enable_external_ts_read` variable when Syncpoint is enabled [#7419](https://github.com/pingcap/tiflow/issues/7419) @[asddongmen](https://github.com/asddongmen) + - Enable transaction split and disable safeMode by default to improve the replication stability [#7505](https://github.com/pingcap/tiflow/issues/7505) @[asddongmen](https://github.com/asddongmen) + + + TiDB Data Migration (DM) + + - Remove the useless `operate-source update` command from dmctl [#7246](https://github.com/pingcap/tiflow/issues/7246) @[buchuitoudegou](https://github.com/buchuitoudegou) + - Fix the issue that DM full import fails if the upstream database uses DDL statements that are incompatible with TiDB. You can create the schema of target tables in TiDB manually in advance using DDL statements supported by TiDB to ensure successful import [#37984](https://github.com/pingcap/tidb/issues/37984) @[lance6716](https://github.com/lance6716) + + + TiDB Lightning + + - Optimize the file scanning logic to accelerate the scan of schema files [#38598](https://github.com/pingcap/tidb/issues/38598) @[dsdashun](https://github.com/dsdashun) + +## Bug fixes + ++ TiDB + + - Fix the potential issue of index inconsistency that occurs after you create a new index [#38165](https://github.com/pingcap/tidb/issues/38165) @[tangenta](https://github.com/tangenta) + - Fix a permission issue of the `INFORMATION_SCHEMA.TIKV_REGION_STATUS` table [#38407](https://github.com/pingcap/tidb/issues/38407) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that the `grantor` field is missing in the `mysql.tables_priv` table [#38293](https://github.com/pingcap/tidb/issues/38293) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that the join result of common table expressions might be wrong [#38170](https://github.com/pingcap/tidb/issues/38170) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the union result of common table expressions might be wrong [#37928](https://github.com/pingcap/tidb/issues/37928) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the information in the **transaction region num** monitoring panel is incorrect [#38139](https://github.com/pingcap/tidb/issues/38139) @[jackysp](https://github.com/jackysp) + - Fix the issue that the system variable [`tidb_constraint_check_in_place_pessimistic`](/system-variables.md#tidb_constraint_check_in_place_pessimistic-new-in-v630) might affect internal transactions. The variable scope is modified to SESSION. [#38766](https://github.com/pingcap/tidb/issues/38766) @[ekexium](https://github.com/ekexium) + - Fix the issue that conditions in a query are mistakenly pushed down to projections [#35623](https://github.com/pingcap/tidb/issues/35623) @[Reminiscent](https://github.com/Reminiscent) + - Fix the issue that the wrong `isNullRejected` check results for `AND` and `OR` cause wrong query results [#38304]( https://github.com/pingcap/tidb/issues/38304) @[Yisaer](https://github.com/Yisaer) + - Fix the issue that `ORDER BY` in `GROUP_CONCAT` is not considered when the outer join is eliminated, which causes wrong query results [#18216](https://github.com/pingcap/tidb/issues/18216) @[winoros](https://github.com/winoros) + - Fix the issue of the wrong query result that occurs when the mistakenly pushed-down conditions are discarded by Join Reorder [#38736](https://github.com/pingcap/tidb/issues/38736) @[winoros](https://github.com/winoros) + ++ TiKV + + - Fix the issue that TiDB fails to start on Gitpod when there are multiple `cgroup` and `mountinfo` records [#13660](https://github.com/tikv/tikv/issues/13660) @[tabokie](https://github.com/tabokie) + - Fix the wrong expression of a TiKV metric `tikv_gc_compaction_filtered` [#13537](https://github.com/tikv/tikv/issues/13537) @[Defined2014](https://github.com/Defined2014) + - Fix the performance issue caused by the abnormal `delete_files_in_range` [#13534](https://github.com/tikv/tikv/issues/13534) @[tabokie](https://github.com/tabokie) + - Fix abnormal Region competition caused by expired lease during snapshot acquisition [#13553](https://github.com/tikv/tikv/issues/13553) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + - Fix errors occurred when `FLASHBACK` fails in the first batch [#13672](https://github.com/tikv/tikv/issues/13672) [#13704](https://github.com/tikv/tikv/issues/13704) [#13723](https://github.com/tikv/tikv/issues/13723) @[HuSharp](https://github.com/HuSharp) + ++ PD + + - Fix inaccurate Stream timeout and accelerate leader switchover [#5207](https://github.com/tikv/pd/issues/5207) @[CabinfeverB](https://github.com/CabinfeverB) + ++ TiFlash + + - Fix the OOM issue due to oversized WAL files that occurs when PageStorage GC does not clear the Page deletion marker properly [#6163](https://github.com/pingcap/tiflash/issues/6163) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + TiDB Dashboard + + - Fix the TiDB OOM issue when querying execution plans of certain complex SQL statements [#1386](https://github.com/pingcap/tidb-dashboard/issues/1386) @[baurine](https://github.com/baurine) + - Fix the issue that the Top SQL switch might not take effect when NgMonitoring loses the connection to the PD nodes [#164](https://github.com/pingcap/ng-monitoring/issues/164) @[zhongzc](https://github.com/zhongzc) + + + Backup & Restore (BR) + + - Fix the restoration failure issue caused by PD leader switch during the restoration process [#36910](https://github.com/pingcap/tidb/issues/36910) @[MoCuishle28](https://github.com/MoCuishle28) + - Fix the issue that the log backup task cannot be paused [#38250](https://github.com/pingcap/tidb/issues/38250) @[joccau](https://github.com/joccau) + - Fix the issue that when BR deletes log backup data, it mistakenly deletes data that should not be deleted [#38939](https://github.com/pingcap/tidb/issues/38939) @[Leavrth](https://github.com/leavrth) + - Fix the issue that BR fails to delete data when deleting the log backup data stored in Azure Blob Storage or Google Cloud Storage for the first time [#38229](https://github.com/pingcap/tidb/issues/38229) @[Leavrth](https://github.com/leavrth) + + + TiCDC + + - Fix the issue that `sasl-password` in the `changefeed query` result is not masked [#7182](https://github.com/pingcap/tiflow/issues/7182) @[dveeden](https://github.com/dveeden) + - Fix the issue that TiCDC might become unavailable when too many operations in an etcd transaction are committed [#7131](https://github.com/pingcap/tiflow/issues/7131) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that redo logs might be deleted incorrectly [#6413](https://github.com/pingcap/tiflow/issues/6413) @[asddongmen](https://github.com/asddongmen) + - Fix performance regression when replicating wide tables in Kafka Sink V2 [#7344](https://github.com/pingcap/tiflow/issues/7344) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that checkpoint ts might be advanced incorrectly [#7274](https://github.com/pingcap/tiflow/issues/7274) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that too many logs are printed due to improper log level of the mounter module [#7235](https://github.com/pingcap/tiflow/issues/7235) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that a TiCDC cluster might have two owners [#4051](https://github.com/pingcap/tiflow/issues/4051) @[asddongmen](https://github.com/asddongmen) + + + TiDB Data Migration (DM) + + - Fix the issue that DM WebUI generates the wrong `allow-list` parameter [#7096](https://github.com/pingcap/tiflow/issues/7096) @[zoubingwu](https://github.com/zoubingwu) + - Fix the issue that a DM-worker has a certain probability of triggering data race when it starts or stops [#6401](https://github.com/pingcap/tiflow/issues/6401) @[liumengya94](https://github.com/liumengya94) + - Fix the issue that when DM replicates an `UPDATE` or `DELETE` statement but the corresponding row data does not exist, DM silently ignores the event [#6383](https://github.com/pingcap/tiflow/issues/6383) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that the `secondsBehindMaster` field is not displayed after you run the `query-status` command [#7189](https://github.com/pingcap/tiflow/issues/7189) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that updating the checkpoint may trigger a large transaction [#5010](https://github.com/pingcap/tiflow/issues/5010) @[lance6716](https://github.com/lance6716) + - Fix the issue that in full task mode, when a task enters the sync stage and fails immediately, DM may lose upstream table schema information [#7159](https://github.com/pingcap/tiflow/issues/7159) @[lance6716](https://github.com/lance6716) + - Fix the issue that deadlock may be triggered when the consistency check is enabled [#7241](https://github.com/pingcap/tiflow/issues/7241) @[buchuitoudegou](https://github.com/buchuitoudegou) + - Fix the issue that task precheck requires the `SELECT` privilege for the `INFORMATION_SCHEMA` table [#7317](https://github.com/pingcap/tiflow/issues/7317) @[lance6716](https://github.com/lance6716) + - Fix the issue that an empty TLS configuration causes an error [#7384](https://github.com/pingcap/tiflow/issues/7384) @[liumengya94](https://github.com/liumengya94) + + + TiDB Lightning + + - Fix the import performance degradation when importing the Apache Parquet files to the target tables that contain the string type columns in the`binary` encoding format [#38351](https://github.com/pingcap/tidb/issues/38351) @[dsdashun](https://github.com/dsdashun) + + + TiDB Dumpling + + - Fix the issue that Dumpling might time out when exporting a lot of tables [#36549](https://github.com/pingcap/tidb/issues/36549) @[lance6716](https://github.com/lance6716) + - Fix lock errors reported when consistency lock is enabled but the upstream has no target table [#38683](https://github.com/pingcap/tidb/issues/38683) @[lance6716](https://github.com/lance6716) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [645775992](https://github.com/645775992) +- [An-DJ](https://github.com/An-DJ) +- [AndrewDi](https://github.com/AndrewDi) +- [erwadba](https://github.com/erwadba) +- [fuzhe1989](https://github.com/fuzhe1989) +- [goldwind-ting](https://github.com/goldwind-ting) (First-time contributor) +- [h3n4l](https://github.com/h3n4l) +- [igxlin](https://github.com/igxlin) (First-time contributor) +- [ihcsim](https://github.com/ihcsim) +- [JigaoLuo](https://github.com/JigaoLuo) +- [morgo](https://github.com/morgo) +- [Ranxy](https://github.com/Ranxy) +- [shenqidebaozi](https://github.com/shenqidebaozi) (First-time contributor) +- [taofengliu](https://github.com/taofengliu) (First-time contributor) +- [TszKitLo40](https://github.com/TszKitLo40) +- [wxbty](https://github.com/wxbty) (First-time contributor) +- [zgcbj](https://github.com/zgcbj) diff --git a/releases/release-6.5.1.md b/releases/release-6.5.1.md new file mode 100644 index 0000000000000..b463a79b3d95c --- /dev/null +++ b/releases/release-6.5.1.md @@ -0,0 +1,187 @@ +--- +title: TiDB 6.5.1 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 6.5.1. +--- + +# TiDB 6.5.1 Release Notes + +Release date: March 10, 2023 + +TiDB version: 6.5.1 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v6.5/production-deployment-using-tiup) + +## Compatibility changes + +- Starting from February 20, 2023, the [telemetry feature](/telemetry.md) is disabled by default in new versions of TiDB and TiDB Dashboard, including v6.5.1, and usage information is not collected and shared with PingCAP. Before upgrading to these versions, if the cluster uses the default telemetry configuration, the telemetry feature is disabled after the upgrade. See [TiDB Release Timeline](/releases/release-timeline.md) for specific versions. + + - The default value of the [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402) system variable is changed from `ON` to `OFF`. + - The default value of the TiDB [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402) configuration item is changed from `true` to `false`. + - The default value of the PD [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) configuration item is changed from `true` to `false`. + +- Starting from v1.11.3, the telemetry feature is disabled by default in newly deployed TiUP, and usage information is not collected. If you upgrade from a TiUP version earlier than v1.11.3 to v1.11.3 or a later version, the telemetry feature keeps the same status as before the upgrade. + +- No longer support modifying column types on partitioned tables because of potential correctness issues. [#40620](https://github.com/pingcap/tidb/issues/40620) @[mjonss](https://github.com/mjonss) + +- The default value of the TiKV [`advance-ts-interval`](/tikv-configuration-file.md#advance-ts-interval) configuration item is changed from `1s` to `20s`. You can modify this configuration item to reduce the latency and improve the timeliness of the Stale Read data. See [Reduce Stale Read latency](/stale-read.md#reduce-stale-read-latency) for details. + +## Improvements + ++ TiDB + + - Starting from v6.5.1, the TiDB cluster deployed by TiDB Operator v1.4.3 or higher supports IPv6 addresses. This means that TiDB can support a larger address space and bring you better security and network performance. + + - Full support for IPv6 addressing: TiDB supports using IPv6 addresses for all network connections, including client connections, internal communication between nodes, and communication with external systems. + - Dual-stack support: If you are not ready to fully switch to IPv6 yet, TiDB also supports dual-stack networks. This means that you can use both IPv4 and IPv6 addresses in the same TiDB cluster and choose a network deployment mode that prioritizes IPv6 by configuration. + + For more information on IPv6 deployment, see [TiDB on Kubernetes documentation](https://docs.pingcap.com/tidb-in-kubernetes/stable/configure-a-tidb-cluster#ipv6-support). + + - Support specifying the SQL script executed upon TiDB cluster initialization [#35624](https://github.com/pingcap/tidb/issues/35624) @[morgo](https://github.com/morgo) + + TiDB v6.5.1 adds a new configuration item [`initialize-sql-file`](https://docs.pingcap.com/tidb/v6.5/tidb-configuration-file#initialize-sql-file-new-in-v651). When you start a TiDB cluster for the first time, you can specify the SQL script to be executed by configuring the command line parameter `--initialize-sql-file`. You can use this feature when you need to perform such operations as modifying the value of a system variable, creating a user, or granting privileges. For more information, see [documentation](https://docs.pingcap.com/tidb/v6.5/tidb-configuration-file#initialize-sql-file-new-in-v651). + + - Clear expired region cache regularly to avoid memory leak and performance degradation [#40461](https://github.com/pingcap/tidb/issues/40461) @[sticnarf](https://github.com/sticnarf) + - Add a new configuration item `--proxy-protocol-fallbackable` to control whether to enable PROXY protocol fallback mode. When this parameter is set to `true`, TiDB accepts PROXY client connections and client connections without any PROXY protocol header [#41409](https://github.com/pingcap/tidb/issues/41409) @[blacktear23](https://github.com/blacktear23) + - Improve the accuracy of Memory Tracker [#40900](https://github.com/pingcap/tidb/issues/40900) [#40500](https://github.com/pingcap/tidb/issues/40500) @[wshwsh12](https://github.com/wshwsh12) + - When the plan cache fails to take effect, the system returns the reason as a warning [#40210](https://github.com/pingcap/tidb/pull/40210) @[qw4990](https://github.com/qw4990) + - Improve the optimizer strategy for out-of-range estimation [#39008](https://github.com/pingcap/tidb/issues/39008) @[time-and-fate](https://github.com/time-and-fate) + ++ TiKV + + - Support starting TiKV on a CPU with less than 1 core [#13586](https://github.com/tikv/tikv/issues/13586) [#13752](https://github.com/tikv/tikv/issues/13752) [#14017](https://github.com/tikv/tikv/issues/14017) @[andreid-db](https://github.com/andreid-db) + - Increase the thread limit of the Unified Read Pool (`readpool.unified.max-thread-count`) to 10 times the CPU quota, to better handle high-concurrency queries [#13690](https://github.com/tikv/tikv/issues/13690) @[v01dstar](https://github.com/v01dstar) + - Change the default value of `resolved-ts.advance-ts-interval` from `"1s"` to `"20s"`, to reduce cross-region traffic [#14100](https://github.com/tikv/tikv/issues/14100) @[overvenus](https://github.com/overvenus) + ++ TiFlash + + - Accelerate TiFlash startup greatly when the data volume is large [#6395](https://github.com/pingcap/tiflash/issues/6395) @[hehechen](https://github.com/hehechen) + ++ Tools + + + Backup & Restore (BR) + + - Optimize the concurrency of downloading log backup files on the TiKV side to improve the performance of PITR in regular scenarios [#14206](https://github.com/tikv/tikv/issues/14206) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Enable pull-based sink to optimize system throughput [#8232](https://github.com/pingcap/tiflow/issues/8232) @[hi-rustin](https://github.com/Rustin170506) + - Support storing redo logs to GCS-compatible or Azure-compatible object storage [#7987](https://github.com/pingcap/tiflow/issues/7987) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Implement MQ sink and MySQL sink in the asynchronous mode to improve the sink throughput [#5928](https://github.com/pingcap/tiflow/issues/5928) @[amyangfei](https://github.com/amyangfei) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Bug fixes + ++ TiDB + + - Fix the issue that the [`pessimistic-auto-commit`](/tidb-configuration-file.md#pessimistic-auto-commit-new-in-v600) configuration item does not take effect for point-get queries [#39928](https://github.com/pingcap/tidb/issues/39928) @[zyguan](https://github.com/zyguan) + - Fix the issue that the `INSERT` or `REPLACE` statements might panic in long session connections [#40351](https://github.com/pingcap/tidb/issues/40351) @[winoros](https://github.com/winoros) + - Fix the issue that `auto analyze` causes graceful shutdown to take a long time [#40038](https://github.com/pingcap/tidb/issues/40038) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that data race might occur during DDL ingestion [#40970](https://github.com/pingcap/tidb/issues/40970) @[tangenta](https://github.com/tangenta) + - Fix the issue that data race might occur when an index is added [#40879](https://github.com/pingcap/tidb/issues/40879) @[tangenta](https://github.com/tangenta) + - Fix the issue that the adding index operation is inefficient due to invalid Region cache when there are many Regions in a table [#38436](https://github.com/pingcap/tidb/issues/38436) @[tangenta](https://github.com/tangenta) + - Fix the issue that TiDB might deadlock during initialization [#40408](https://github.com/pingcap/tidb/issues/40408) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that unexpected data is read because TiDB improperly handles `NULL` values when constructing key ranges [#40158](https://github.com/pingcap/tidb/issues/40158) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the value of system variables might be incorrectly modified in some cases due to memory reuse [#40979](https://github.com/pingcap/tidb/issues/40979) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that a TTL task fails if the primary key of the table contains an `ENUM` column [#40456](https://github.com/pingcap/tidb/issues/40456) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that TiDB panics when adding a unique index [#40592](https://github.com/pingcap/tidb/issues/40592) @[tangenta](https://github.com/tangenta) + - Fix the issue that some truncate operations cannot be blocked by MDL when truncating the same table concurrently [#40484](https://github.com/pingcap/tidb/issues/40484) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that TiDB cannot restart after global bindings are created for partition tables in dynamic trimming mode [#40368](https://github.com/pingcap/tidb/issues/40368) @[Yisaer](https://github.com/Yisaer) + - Fix the issue that reading data using the "cursor read" method might return an error because of GC [#39447](https://github.com/pingcap/tidb/issues/39447) @[zyguan](https://github.com/zyguan) + - Fix the issue that the `EXECUTE` information is null in the result of `SHOW PROCESSLIST` [#41156](https://github.com/pingcap/tidb/issues/41156) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that when `globalMemoryControl` is killing a query, the `KILL` operation might not end [#41057](https://github.com/pingcap/tidb/issues/41057) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that TiDB might panic after `indexMerge` encounters an error [#41047](https://github.com/pingcap/tidb/issues/41047) [#40877](https://github.com/pingcap/tidb/issues/40877) @[guo-shaoge](https://github.com/guo-shaoge) @[windtalker](https://github.com/windtalker) + - Fix the issue that the `ANALYZE` statement might be terminated by `KILL` [#41825](https://github.com/pingcap/tidb/issues/41825) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that goroutine leak might occur in `indexMerge` [#41545](https://github.com/pingcap/tidb/issues/41545) [#41605](https://github.com/pingcap/tidb/issues/41605) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue of potential wrong results when comparing unsigned `TINYINT`/`SMALLINT`/`INT` values with `DECIMAL`/`FLOAT`/`DOUBLE` values smaller than `0` [#41736](https://github.com/pingcap/tidb/issues/41736) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that enabling `tidb_enable_reuse_chunk` might lead to memory leak [#40987](https://github.com/pingcap/tidb/issues/40987) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that data race in time zone might cause data-index inconsistency [#40710](https://github.com/pingcap/tidb/issues/40710) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the scan detail information during the execution of `batch cop` might be inaccurate [#41582](https://github.com/pingcap/tidb/issues/41582) @[you06](https://github.com/you06) + - Fix the issue that the upper concurrency of `cop` is not limited [#41134](https://github.com/pingcap/tidb/issues/41134) @[you06](https://github.com/you06) + - Fix the issue that the `statement context` in `cursor read` is mistakenly cached [#39998](https://github.com/pingcap/tidb/issues/39998) @[zyguan](https://github.com/zyguan) + - Periodically clean up stale Region cache to avoid memory leak and performance degradation [#40355](https://github.com/pingcap/tidb/issues/40355) @[sticnarf](https://github.com/sticnarf) + - Fix the issue that using plan cache on queries that contain `year const` might get a wrong result [#41626](https://github.com/pingcap/tidb/issues/41626) @[qw4990](https://github.com/qw4990) + - Fix the issue of large estimation errors when querying with a large range and a large amount of data modification [#39593](https://github.com/pingcap/tidb/issues/39593) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that some conditions cannot be pushed down through Join operators when using Plan Cache [#40093](https://github.com/pingcap/tidb/issues/40093) [#38205](https://github.com/pingcap/tidb/issues/38205) @[qw4990](https://github.com/qw4990) + - Fix the issue that IndexMerge plans might generate incorrect ranges on the SET type columns [#41273](https://github.com/pingcap/tidb/issues/41273) [#41293](https://github.com/pingcap/tidb/issues/41293) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that Plan Cache might cache FullScan plans when processing `int_col decimal` conditions [#40679](https://github.com/pingcap/tidb/issues/40679) [#41032](https://github.com/pingcap/tidb/issues/41032) @[qw4990](https://github.com/qw4990) + - Fix the issue that Plan Cache might cache FullScan plans when processing `int_col in (decimal...)` conditions [#40224](https://github.com/pingcap/tidb/issues/40224) @[qw4990](https://github.com/qw4990) + - Fix the issue that the `ignore_plan_cache` hint might not work for `INSERT` statements [#40079](https://github.com/pingcap/tidb/issues/40079) [#39717](https://github.com/pingcap/tidb/issues/39717) @[qw4990](https://github.com/qw4990) + - Fix the issue that Auto Analyze might hinder TiDB from exiting [#40038](https://github.com/pingcap/tidb/issues/40038) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that incorrect access intervals might be constructed on Unsigned Primary Keys in partitioned tables [#40309](https://github.com/pingcap/tidb/issues/40309) @[winoros](https://github.com/winoros) + - Fix the issue that Plan Cache might cache Shuffle operators and return incorrect results [#38335](https://github.com/pingcap/tidb/issues/38335) @[qw4990](https://github.com/qw4990) + - Fix the issue that creating Global Binding on partitioned tables might cause TiDB to fail to start [#40368](https://github.com/pingcap/tidb/issues/40368) @[Yisaer](https://github.com/Yisaer) + - Fix the issue that query plan operators might be missing in slow logs [#41458](https://github.com/pingcap/tidb/issues/41458) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that incorrect results might be returned when TopN operators with virtual columns are mistakenly pushing down to TiKV or TiFlash [#41355](https://github.com/pingcap/tidb/issues/41355) @[Dousir9](https://github.com/Dousir9) + - Fix the issue of inconsistent data when adding indexes [#40698](https://github.com/pingcap/tidb/issues/40698) [#40730](https://github.com/pingcap/tidb/issues/40730) [#41459](https://github.com/pingcap/tidb/issues/41459) [#40464](https://github.com/pingcap/tidb/issues/40464) [#40217](https://github.com/pingcap/tidb/issues/40217) @[tangenta](https://github.com/tangenta) + - Fix the issue of getting the `Pessimistic lock not found` error when adding indexes [#41515](https://github.com/pingcap/tidb/issues/41515) @[tangenta](https://github.com/tangenta) + - Fix the issue of misreported duplicate key errors when adding unique indexes [#41630](https://github.com/pingcap/tidb/issues/41630) @[tangenta](https://github.com/tangenta) + - Fix the issue of performance degradation when using `paging` in TiDB [#40741](https://github.com/pingcap/tidb/issues/40741) @[solotzg](https://github.com/solotzg) + ++ TiKV + + - Fix the issue that Resolved TS causes higher network traffic [#14092](https://github.com/tikv/tikv/issues/14092) @[overvenus](https://github.com/overvenus) + - Fix the data inconsistency issue caused by network failure between TiDB and TiKV during the execution of a DML after a failed pessimistic DML [#14038](https://github.com/tikv/tikv/issues/14038) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix an error that occurs when casting the `const Enum` type to other types [#14156](https://github.com/tikv/tikv/issues/14156) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the paging in a cop task is inaccurate [#14254](https://github.com/tikv/tikv/issues/14254) @[you06](https://github.com/you06) + - Fix the issue that the `scan_detail` field is inaccurate in `batch_cop` mode [#14109](https://github.com/tikv/tikv/issues/14109) @[you06](https://github.com/you06) + - Fix a potential error in the Raft Engine that might cause TiKV to detect Raft data corruption and fail to restart [#14338](https://github.com/tikv/tikv/issues/14338) @[tonyxuqqi](https://github.com/tonyxuqqi) + ++ PD + + - Fix the issue that the execution `replace-down-peer` slows down under certain conditions [#5788](https://github.com/tikv/pd/issues/5788) @[HundunDM](https://github.com/HunDunDM) + - Fix the issue that PD might unexpectedly add multiple Learners to a Region [#5786](https://github.com/tikv/pd/issues/5786) @[HunDunDM](https://github.com/HunDunDM) + - Fix the issue that the Region Scatter task generates redundant replicas unexpectedly [#5909](https://github.com/tikv/pd/issues/5909) @[HundunDM](https://github.com/HunDunDM) + - Fix the PD OOM issue that occurs when the calls of `ReportMinResolvedTS` are too frequent [#5965](https://github.com/tikv/pd/issues/5965) @[HundunDM](https://github.com/HunDunDM) + - Fix the issue that the Region Scatter might cause uneven distribution of leader [#6017](https://github.com/tikv/pd/issues/6017) @[HunDunDM](https://github.com/HunDunDM) + ++ TiFlash + + - Fix the issue that semi-joins use excessive memory when calculating Cartesian products [#6730](https://github.com/pingcap/tiflash/issues/6730) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that TiFlash log search is too slow [#6829](https://github.com/pingcap/tiflash/issues/6829) @[hehechen](https://github.com/hehechen) + - Fix the issue that TiFlash cannot start because files are mistakenly deleted after repeated restarts [#6486](https://github.com/pingcap/tiflash/issues/6486) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might report an error when performing a query after adding a new column [#6726](https://github.com/pingcap/tiflash/issues/6726) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash does not support IPv6 configuration [#6734](https://github.com/pingcap/tiflash/issues/6734) @[ywqzzy](https://github.com/ywqzzy) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the connection failure between PD and tidb-server causes PITR backup progress not to advance [#41082](https://github.com/pingcap/tidb/issues/41082) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV cannot listen to PITR tasks due to the connection failure between PD and TiKV [#14159](https://github.com/tikv/tikv/issues/14159) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that PITR does not support configuration changes for PD clusters [#14165](https://github.com/tikv/tikv/issues/14165) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the PITR feature does not support CA-bundles [#38775](https://github.com/pingcap/tidb/issues/38775) @[3pointer](https://github.com/3pointer) + - Fix the issue that when a PITR backup task is deleted, the residual backup data causes data inconsistency in new tasks [#40403](https://github.com/pingcap/tidb/issues/40403) @[joccau](https://github.com/joccau) + - Fix the issue that causes panic when BR parses the `backupmeta` file [#40878](https://github.com/pingcap/tidb/issues/40878) @[MoCuishle28](https://github.com/MoCuishle28) + - Fix the issue that restore is interrupted due to failure in getting the Region size [#36053](https://github.com/pingcap/tidb/issues/36053) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the frequency of `resolve lock` is too high when there is no PITR backup task in the TiDB cluster [#40759](https://github.com/pingcap/tidb/issues/40759) @[joccau](https://github.com/joccau) + - Fix the issue that restoring data to a cluster on which the log backup is running causes the log backup file unable to be restored [#40797](https://github.com/pingcap/tidb/issues/40797) @[Leavrth](https://github.com/Leavrth) + - Fix the panic issue that occurs when attempting to resume backup from a checkpoint after a full backup failure [#40704](https://github.com/pingcap/tidb/issues/40704) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that PITR errors are overwritten [#40576](https://github.com/pingcap/tidb/issues/40576) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that checkpoints do not advance in PITR backup tasks when the advance owner and gc owner are different [#41806](https://github.com/pingcap/tidb/issues/41806) @[joccau](https://github.com/joccau) + + + TiCDC + + - Fix the issue that changefeed might get stuck in special scenarios such as when scaling in or scaling out TiKV or TiCDC nodes [#8174](https://github.com/pingcap/tiflow/issues/8174) @[hicqu](https://github.com/hicqu) + - Fix the issue that precheck is not performed on the storage path of redo log [#6335](https://github.com/pingcap/tiflow/issues/6335) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue of insufficient duration that redo log can tolerate for S3 storage failure [#8089](https://github.com/pingcap/tiflow/issues/8089) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that `transaction_atomicity` and `protocol` cannot be updated via the configuration file [#7935](https://github.com/pingcap/tiflow/issues/7935) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the checkpoint cannot advance when TiCDC replicates an excessively large number of tables [#8004](https://github.com/pingcap/tiflow/issues/8004) @[overvenus](https://github.com/overvenus) + - Fix the issue that applying redo log might cause OOM when the replication lag is excessively high [#8085](https://github.com/pingcap/tiflow/issues/8085) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the performance degrades when redo log is enabled to write meta [#8074](https://github.com/pingcap/tiflow/issues/8074) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix a bug that the context deadline is exceeded when TiCDC replicates data without splitting large transactions [#7982](https://github.com/pingcap/tiflow/issues/7982) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that pausing a changefeed when PD is abnormal results in incorrect status [#8330](https://github.com/pingcap/tiflow/issues/8330) @[sdojjy](https://github.com/sdojjy) + - Fix the data inconsistency that occurs when replicating data to a TiDB or MySQL sink and when `CHARACTER SET` is specified on the column that has the non-null unique index without a primary key [#8420](https://github.com/pingcap/tiflow/issues/8420) @[asddongmen](https://github.com/asddongmen) + - Fix the panic issue in table scheduling and blackhole sink [#8024](https://github.com/pingcap/tiflow/issues/8024) [#8142](https://github.com/pingcap/tiflow/issues/8142) @[hicqu](https://github.com/hicqu) + + + TiDB Data Migration (DM) + + - Fix the issue that the `binlog-schema delete` command fails to execute [#7373](https://github.com/pingcap/tiflow/issues/7373) @[liumengya94](https://github.com/liumengya94) + - Fix the issue that the checkpoint does not advance when the last binlog is a skipped DDL [#8175](https://github.com/pingcap/tiflow/issues/8175) @[D3Hunter](https://github.com/D3Hunter) + - Fix a bug that when the expression filters of both "update" and "non-update" types are specified in one table, all `UPDATE` statements are skipped [#7831](https://github.com/pingcap/tiflow/issues/7831) @[lance6716](https://github.com/lance6716) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning prechecks cannot find dirty data left by previously failed imports [#39477](https://github.com/pingcap/tidb/issues/39477) @[dsdashun](https://github.com/dsdashun) + - Fix the issue that TiDB Lightning panics in the split-region phase [#40934](https://github.com/pingcap/tidb/issues/40934) @[lance6716](https://github.com/lance6716) + - Fix the issue that the conflict resolution logic (`duplicate-resolution`) might lead to inconsistent checksums [#40657](https://github.com/pingcap/tidb/issues/40657) @[sleepymole](https://github.com/sleepymole) + - Fix the issue that TiDB Lightning might incorrectly skip conflict resolution when all but the last TiDB Lightning instance encounters a local duplicate record during a parallel import [#40923](https://github.com/pingcap/tidb/issues/40923) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that when importing data in Local Backend mode, the target columns do not automatically generate data if the compound primary key of the imported target table has an `auto_random` column and no value for the column is specified in the source data [#41454](https://github.com/pingcap/tidb/issues/41454) @[D3Hunter](https://github.com/D3Hunter) diff --git a/releases/release-6.5.10.md b/releases/release-6.5.10.md new file mode 100644 index 0000000000000..9971b6c14ab4d --- /dev/null +++ b/releases/release-6.5.10.md @@ -0,0 +1,148 @@ +--- +title: TiDB 6.5.10 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 6.5.10. +--- + +# TiDB 6.5.10 Release Notes + +Release date: June 20, 2024 + +TiDB version: 6.5.10 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v6.5/production-deployment-using-tiup) + +## Compatibility changes + +- In earlier versions, when processing a transaction containing `UPDATE` changes, if the primary key or non-null unique index value is modified in an `UPDATE` event, TiCDC splits this event into `DELETE` and `INSERT` events. Starting from v6.5.10, when using the MySQL sink, TiCDC splits an `UPDATE` event into `DELETE` and `INSERT` events if the transaction `commitTS` for the `UPDATE` change is less than TiCDC `thresholdTS` (which is the current timestamp fetched from PD when TiCDC starts replicating the corresponding table to the downstream). This behavior change addresses the issue of downstream data inconsistencies caused by the potentially incorrect order of `UPDATE` events received by TiCDC, which can lead to an incorrect order of split `DELETE` and `INSERT` events. For more information, see [documentation](https://docs.pingcap.com/tidb/v6.5/ticdc-split-update-behavior#split-update-events-for-mysql-sinks). [#10918](https://github.com/pingcap/tiflow/issues/10918) @[lidezhu](https://github.com/lidezhu) +- Must set the line terminator when using TiDB Lightning `strict-format` to import CSV files [#37338](https://github.com/pingcap/tidb/issues/37338) @[lance6716](https://github.com/lance6716) + +## Improvements + ++ TiDB + + - Improve the MySQL compatibility of expression default values displayed in the output of `SHOW CREATE TABLE` [#52939](https://github.com/pingcap/tidb/issues/52939) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Remove stores without Regions during MPP load balancing [#52313](https://github.com/pingcap/tidb/issues/52313) @[xzhangxian1008](https://github.com/xzhangxian1008) + ++ TiKV + + - Accelerate the shutdown speed of TiKV [#16680](https://github.com/tikv/tikv/issues/16680) @[LykxSassinator](https://github.com/LykxSassinator) + - Add monitoring metrics for the queue time for processing CDC events to facilitate troubleshooting downstream CDC event latency issues [#16282](https://github.com/tikv/tikv/issues/16282) @[hicqu](https://github.com/hicqu) + ++ Tools + + + Backup & Restore (BR) + + - BR cleans up empty SST files during data recovery [#16005](https://github.com/tikv/tikv/issues/16005) @[Leavrth](https://github.com/Leavrth) + - Increase the number of retries for failures caused by DNS errors [#53029](https://github.com/pingcap/tidb/issues/53029) @[YuJuncen](https://github.com/YuJuncen) + - Increase the number of retries for failures caused by the absence of a leader in a Region [#54017](https://github.com/pingcap/tidb/issues/54017) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Support directly outputting raw events when the downstream is a Message Queue (MQ) or cloud storage [#11211](https://github.com/pingcap/tiflow/issues/11211) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Improve memory stability during data recovery using redo logs to reduce the probability of OOM [#10900](https://github.com/pingcap/tiflow/issues/10900) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Significantly improve the stability of data replication in transaction conflict scenarios, with up to 10 times performance improvement [#10896](https://github.com/pingcap/tiflow/issues/10896) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Bug fixes + ++ TiDB + + - Fix the issue that querying metadata during statistics initialization might cause OOM [#52219](https://github.com/pingcap/tidb/issues/52219) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that for tables containing auto-increment columns with `AUTO_ID_CACHE=1`, setting `auto_increment_increment` and `auto_increment_offset` system variables to non-default values might cause incorrect auto-increment ID allocation [#52622](https://github.com/pingcap/tidb/issues/52622) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that restoring a table with `AUTO_ID_CACHE=1` using the `RESTORE` statement might cause a `Duplicate entry` error [#52680](https://github.com/pingcap/tidb/issues/52680) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `STATE` field in the `INFORMATION_SCHEMA.TIDB_TRX` table is empty due to the `size` of the `STATE` field not being defined [#53026](https://github.com/pingcap/tidb/issues/53026) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that TiDB does not create corresponding statistics metadata (`stats_meta`) when creating a table with foreign keys [#53652](https://github.com/pingcap/tidb/issues/53652) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the statistics synchronous loading mechanism might fail unexpectedly under high query concurrency [#52294](https://github.com/pingcap/tidb/issues/52294) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `Distinct_count` information in GlobalStats might be incorrect [#53752](https://github.com/pingcap/tidb/issues/53752) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the histogram and TopN in the primary key column statistics are not loaded after restarting TiDB [#37548](https://github.com/pingcap/tidb/issues/37548) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that certain filter conditions in queries might cause the planner module to report an `invalid memory address or nil pointer dereference` error [#53582](https://github.com/pingcap/tidb/issues/53582) [#53580](https://github.com/pingcap/tidb/issues/53580) [#53594](https://github.com/pingcap/tidb/issues/53594) [#53603](https://github.com/pingcap/tidb/issues/53603) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `PREPARE`/`EXECUTE` statements with the `CONV` expression containing a `?` argument might result in incorrect query results when executed multiple times [#53505](https://github.com/pingcap/tidb/issues/53505) @[qw4990](https://github.com/qw4990) + - Fix the issue of incorrect WARNINGS information when using Optimizer Hints [#53767](https://github.com/pingcap/tidb/issues/53767) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the query latency of stale reads increases, caused by information schema cache misses [#53428](https://github.com/pingcap/tidb/issues/53428) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that DDL statements incorrectly use etcd and cause tasks to queue up [#52335](https://github.com/pingcap/tidb/issues/52335) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that internal columns are not renamed when executing `RENAME INDEX` to rename expression indexes [#51431](https://github.com/pingcap/tidb/issues/51431) @[ywqzzy](https://github.com/ywqzzy) + - Fix the issue that executing `CREATE OR REPLACE VIEW` concurrently might result in the `table doesn't exist` error [#53673](https://github.com/pingcap/tidb/issues/53673) @[tangenta](https://github.com/tangenta) + - Fix the issue that TiDB might panic when the JOIN condition contains an implicit type conversion [#46556](https://github.com/pingcap/tidb/issues/46556) @[qw4990](https://github.com/qw4990) + - Fix the issue that DDL operations get stuck due to network problems [#47060](https://github.com/pingcap/tidb/issues/47060) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that IndexJoin produces duplicate rows when calculating hash values in the Left Outer Anti Semi type [#52902](https://github.com/pingcap/tidb/issues/52902) @[yibin87](https://github.com/yibin87) + - Fix the issue that subqueries included in the `ALL` function might cause incorrect results [#52755](https://github.com/pingcap/tidb/issues/52755) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `TIMESTAMPADD()` function returns incorrect results [#41052](https://github.com/pingcap/tidb/issues/41052) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that TiDB might crash when `tidb_mem_quota_analyze` is enabled and the memory used by updating statistics exceeds the limit [#52601](https://github.com/pingcap/tidb/issues/52601) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that subqueries in an `UPDATE` list might cause TiDB to panic [#52687](https://github.com/pingcap/tidb/issues/52687) @[winoros](https://github.com/winoros) + - Fix the overflow issue of the `Longlong` type in predicates [#45783](https://github.com/pingcap/tidb/issues/45783) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue of inconsistent data indexes caused by concurrent DML operations when adding a unique index [#52914](https://github.com/pingcap/tidb/issues/52914) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that TiDB might panic when parsing index data [#47115](https://github.com/pingcap/tidb/issues/47115) @[zyguan](https://github.com/zyguan) + - Fix the issue that column pruning without using shallow copies of slices might cause TiDB to panic [#52768](https://github.com/pingcap/tidb/issues/52768) @[winoros](https://github.com/winoros) + - Fix the issue that using a view does not work in recursive CTE [#49721](https://github.com/pingcap/tidb/issues/49721) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `LEADING` hint does not support querying block aliases [#44645](https://github.com/pingcap/tidb/issues/44645) @[qw4990](https://github.com/qw4990) + - Fix the incorrect result of the TopN operator in correlated subqueries [#52777](https://github.com/pingcap/tidb/issues/52777) @[yibin87](https://github.com/yibin87) + - Fix the issue that unstable unique IDs of columns might cause the `UPDATE` statement to return errors [#53236](https://github.com/pingcap/tidb/issues/53236) @[winoros](https://github.com/winoros) + - Fix the issue that TiDB keeps sending probe requests to a TiFlash node that has been offline [#46602](https://github.com/pingcap/tidb/issues/46602) @[zyguan](https://github.com/zyguan) + - Fix the issue that comparing a column of `YEAR` type with an unsigned integer that is out of range causes incorrect results [#50235](https://github.com/pingcap/tidb/issues/50235) @[qw4990](https://github.com/qw4990) + - Fix the issue that AutoID Leader change might cause the value of the auto-increment column to decrease in the case of `AUTO_ID_CACHE=1` [#52600](https://github.com/pingcap/tidb/issues/52600) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that non-BIGINT unsigned integers might produce incorrect results when compared with strings/decimals [#41736](https://github.com/pingcap/tidb/issues/41736) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that data conversion from the `FLOAT` type to the `UNSIGNED` type returns incorrect results [#41736](https://github.com/pingcap/tidb/issues/41736) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that `VAR_SAMP()` cannot be used as a window function [#52933](https://github.com/pingcap/tidb/issues/52933) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that a wrong TableDual plan causes empty query results [#50051](https://github.com/pingcap/tidb/issues/50051) @[onlyacat](https://github.com/onlyacat) + - Fix the issue that the TiDB synchronously loading statistics mechanism retries to load empty statistics indefinitely and prints the `fail to get stats version for this histogram` log [#52657](https://github.com/pingcap/tidb/issues/52657) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that an empty projection causes TiDB to panic [#49109](https://github.com/pingcap/tidb/issues/49109) @[winoros](https://github.com/winoros) + - Fix the issue that the TopN operator might be pushed down incorrectly [#37986](https://github.com/pingcap/tidb/issues/37986) @[qw4990](https://github.com/qw4990) + - Fix the issue that TiDB panics when executing the `SHOW ERRORS` statement with a predicate that is always `true` [#46962](https://github.com/pingcap/tidb/issues/46962) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that the metadata lock fails to prevent DDL operations from executing in the plan cache scenario [#51407](https://github.com/pingcap/tidb/issues/51407) @[wjhuang2016](https://github.com/wjhuang2016) + ++ TiKV + + - Fix the issue that slow `check-leader` operations on one TiKV node cause `resolved-ts` on other TiKV nodes to fail to advance normally [#15999](https://github.com/tikv/tikv/issues/15999) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the `CONV()` function in queries might overflow during numeric system conversion, leading to TiKV panic [#16969](https://github.com/tikv/tikv/issues/16969) @[gengliqi](https://github.com/gengliqi) + - Fix the issue of unstable test cases, ensuring that each test uses an independent temporary directory to avoid online configuration changes affecting other test cases [#16871](https://github.com/tikv/tikv/issues/16871) @[glorv](https://github.com/glorv) + - Fix the issue that the decimal part of the `DECIMAL` type is incorrect in some cases [#16913](https://github.com/tikv/tikv/issues/16913) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that resolve-ts is blocked when a stale Region peer ignores the GC message [#16504](https://github.com/tikv/tikv/issues/16504) @[crazycs520](https://github.com/crazycs520) + ++ PD + + - Fix the issue that the Leader fails to transfer when you switch it between two deployed data centers [#7992](https://github.com/tikv/pd/issues/7992) @[TonsnakeLin](https://github.com/TonsnakeLin) + - Fix the issue that down peers might not recover when using Placement Rules [#7808](https://github.com/tikv/pd/issues/7808) @[rleungx](https://github.com/rleungx) + - Fix the issue that the `Filter target` monitoring metric for PD does not provide scatter range information [#8125](https://github.com/tikv/pd/issues/8125) @[HuSharp](https://github.com/HuSharp) + ++ TiFlash + + - Fix the issue that TiFlash might fail to synchronize schemas after executing `ALTER TABLE ... EXCHANGE PARTITION` across databases [#7296](https://github.com/pingcap/tiflash/issues/7296) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that a query with an empty key range fails to correctly generate read tasks on TiFlash, which might block TiFlash queries [#9108](https://github.com/pingcap/tiflash/issues/9108) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that the `SUBSTRING_INDEX()` function might cause TiFlash to crash in some corner cases [#9116](https://github.com/pingcap/tiflash/issues/9116) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that TiFlash metadata might become corrupted and cause the process to panic when upgrading a cluster from a version earlier than v6.5.0 to v6.5.0 or later [#9039](https://github.com/pingcap/tiflash/issues/9039) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might return transiently incorrect results in high-concurrency read scenarios [#8845](https://github.com/pingcap/tiflash/issues/8845) @[JinheLin](https://github.com/JinheLin) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the test case `TestGetTSWithRetry` takes too long to execute [#52547](https://github.com/pingcap/tidb/issues/52547) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the Region fetched from PD does not have a Leader when restoring data using BR or importing data using TiDB Lightning in physical import mode [#51124](https://github.com/pingcap/tidb/issues/51124) [#50501](https://github.com/pingcap/tidb/issues/50501) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that a PD connection failure could cause the TiDB instance where the log backup advancer owner is located to panic [#52597](https://github.com/pingcap/tidb/issues/52597) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that after pausing, stopping, and rebuilding the log backup task, the task status is normal, but the checkpoint does not advance [#53047](https://github.com/pingcap/tidb/issues/53047) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that data restore is slowed down due to the absence of a leader on a TiKV node [#50566](https://github.com/pingcap/tidb/issues/50566) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the global checkpoint of log backup is advanced ahead of the actual backup file write point due to TiKV restart, which might cause a small amount of backup data loss [#16809](https://github.com/tikv/tikv/issues/16809) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the transfer of PD leaders might cause BR to panic when restoring data [#53724](https://github.com/pingcap/tidb/issues/53724) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that TiKV might panic when resuming a paused log backup task with unstable network connections to PD [#17020](https://github.com/tikv/tikv/issues/17020) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that log backup might be paused after the advancer owner migration [#53561](https://github.com/pingcap/tidb/issues/53561) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that BR fails to correctly identify errors due to multiple nested retries during the restore process [#54053](https://github.com/pingcap/tidb/issues/54053) @[RidRisR](https://github.com/RidRisR) + + + TiCDC + + - Fix the issue that TiCDC fails to create a changefeed with Syncpoint enabled when the downstream database password is Base64 encoded [#10516](https://github.com/pingcap/tiflow/issues/10516) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that `DROP PRIMARY KEY` and `DROP UNIQUE KEY` statements are not replicated correctly [#10890](https://github.com/pingcap/tiflow/issues/10890) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the default value of `TIMEZONE` type is not set according to the correct time zone [#10931](https://github.com/pingcap/tiflow/issues/10931) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Lightning + + - Fix the issue that killing the PD Leader causes TiDB Lightning to report the `invalid store ID 0` error during data import [#50501](https://github.com/pingcap/tidb/issues/50501) @[Leavrth](https://github.com/Leavrth) + - Fix the issue of missing data in the TiDB Lightning Grafana dashboard [#43357](https://github.com/pingcap/tidb/issues/43357) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that TiDB Lightning might print sensitive information to logs in server mode [#36374](https://github.com/pingcap/tidb/issues/36374) @[kennytm](https://github.com/kennytm) + - Fix the issue that TiDB fails to generate auto-increment IDs and reports an error `Failed to read auto-increment value from storage engine` after importing a table with both `SHARD_ROW_ID_BITS` and `AUTO_ID_CACHE=1` set using TiDB Lightning [#52654](https://github.com/pingcap/tidb/issues/52654) @[D3Hunter](https://github.com/D3Hunter) + + + Dumpling + + - Fix the issue that Dumpling reports an error when exporting tables and views at the same time [#53682](https://github.com/pingcap/tidb/issues/53682) @[tangenta](https://github.com/tangenta) + + + TiDB Binlog + + - Fix the issue that deleting rows during the execution of `ADD COLUMN` might report an error `data and columnID count not match` when TiDB Binlog is enabled [#53133](https://github.com/pingcap/tidb/issues/53133) @[tangenta](https://github.com/tangenta) diff --git a/releases/release-6.5.2.md b/releases/release-6.5.2.md new file mode 100644 index 0000000000000..3825d7a6be554 --- /dev/null +++ b/releases/release-6.5.2.md @@ -0,0 +1,108 @@ +--- +title: TiDB 6.5.2 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 6.5.2. +--- + +# TiDB 6.5.2 Release Notes + +Release date: April 21, 2023 + +TiDB version: 6.5.2 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v6.5/production-deployment-using-tiup) + +## Compatibility changes + +- TiCDC fixes the issue of incorrect encoding of `FLOAT` data in Avro [#8490](https://github.com/pingcap/tiflow/issues/8490) @[3AceShowHand](https://github.com/3AceShowHand) + + When upgrading the TiCDC cluster to v6.5.2 or a later v6.5.x version, if a table replicated using Avro contains the `FLOAT` data type, you need to manually adjust the compatibility policy of Confluent Schema Registry to `None` before upgrading so that the changefeed can successfully update the schema. Otherwise, after upgrading, the changefeed will be unable to update the schema and enter an error state. + +- To fix the potential issue of data loss during replication of partitioned tables to storage services, the default value of the TiCDC [`sink.enable-partition-separator`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) configuration item is changed from `false` to `true`. This means that partitions in a table are stored in separate directories by default. It is recommended that you keep the value as `true` to avoid the data loss issue. [#8724](https://github.com/pingcap/tiflow/issues/8724) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Improvements + ++ TiDB + + - Support caching the execution plan for `BatchPointGet` in Prepared Plan Cache [#42125](https://github.com/pingcap/tidb/issues/42125) @[qw4990](https://github.com/qw4990) + - Support more SQL formats for Index Join [#40505](https://github.com/pingcap/tidb/issues/40505) @[Yisaer](https://github.com/Yisaer) + - Change the log level of some Index Merge readers from `"info"` to `"debug"` [#41949](https://github.com/pingcap/tidb/issues/41949) @[yibin87](https://github.com/yibin87) + - Optimize the `distsql_concurrency` setting for Range partitioned tables with Limit to reduce query latency [#41480](https://github.com/pingcap/tidb/issues/41480) @[you06](https://github.com/you06) + ++ TiFlash + + - Reduce CPU consumption of task scheduling during TiFlash reads [#6495](https://github.com/pingcap/tiflash/issues/6495) @[JinheLin](https://github.com/JinheLin) + - Improve performance of data import from BR and TiDB Lightning to TiFlash with default configurations [#7272](https://github.com/pingcap/tiflash/issues/7272) @[breezewish](https://github.com/breezewish) + ++ Tools + + + TiCDC + + - Release TiCDC Open API v2.0 [#8743](https://github.com/pingcap/tiflow/issues/8743) @[sdojjy](https://github.com/sdojjy) + - Introduce `gomemlimit` to prevent TiCDC from OOM issues [#8675](https://github.com/pingcap/tiflow/issues/8675) @[amyangfei](https://github.com/amyangfei) + - Use the multi-statement approach to optimize the replication performance in scenarios involving batch execution of `UPDATE` statements [#8057](https://github.com/pingcap/tiflow/issues/8057) @[amyangfei](https://github.com/amyangfei) + - Support splitting transactions in the redo applier to improve its throughput and reduce RTO in disaster recovery scenarios [#8318](https://github.com/pingcap/tiflow/issues/8318) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support applying DDL events in redo logs [#8361](https://github.com/pingcap/tiflow/issues/8361) @[CharlesCheung96](https://github.com/CharlesCheung96) + + + TiDB Lightning + + - Support importing CSV data files with BOM headers [#40744](https://github.com/pingcap/tidb/issues/40744) @[dsdashun](https://github.com/dsdashun) + +## Bug fixes + ++ TiDB + - Fix the issue that after a new column is added in the cache table, the value is `NULL` instead of the default value of the column [#42928](https://github.com/pingcap/tidb/issues/42928) @[lqs](https://github.com/lqs) + - Fix the issue of DDL retry caused by write conflict when executing `TRUNCATE TABLE` for partitioned tables with many partitions and TiFlash replicas [#42940](https://github.com/pingcap/tidb/issues/42940) @[mjonss](https://github.com/mjonss) + - Fix the issue of missing table names in the `ADMIN SHOW DDL JOBS` result when a `DROP TABLE` operation is being executed [#42268](https://github.com/pingcap/tidb/issues/42268) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB server cannot start due to an error in reading the cgroup information with the error message "can't read file memory.stat from cgroup v1: open /sys/memory.stat no such file or directory" [#42659](https://github.com/pingcap/tidb/issues/42659) @[hawkingrei](https://github.com/hawkingrei) + - Fix frequent write conflicts in transactions when performing DDL data backfill [#24427](https://github.com/pingcap/tidb/issues/24427) @[mjonss](https://github.com/mjonss) + - Fix the issue that TiDB panic occurs due to inconsistent InfoSchema being obtained when generating the execution plan [#41622](https://github.com/pingcap/tidb/issues/41622) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that when modifying the floating-point type using DDL to keep the length unchanged and reduce the decimal places, the old data still remains the same [#41281](https://github.com/pingcap/tidb/issues/41281) @[zimulala](https://github.com/zimulala) + - Fix the issue that after executing `PointUpdate` within a transaction, TiDB returns incorrect results for the `SELECT` statement [#28011](https://github.com/pingcap/tidb/issues/28011) @[zyguan](https://github.com/zyguan) + - Fix the issue that, when using Cursor Fetch and running other statements among Execute, Fetch, and Close, the Fetch and Close commands might return incorrect results or cause TiDB to panic [#40094](https://github.com/pingcap/tidb/issues/40094) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `INSERT IGNORE` and `REPLACE` statements do not lock keys that do not modify values [#42121](https://github.com/pingcap/tidb/issues/42121) @[zyguan](https://github.com/zyguan) + - Fix the issue that TiFlash reports an error for generated columns during execution [#40663](https://github.com/pingcap/tidb/issues/40663) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiDB might produce incorrect results when different partitioned tables appear in a single SQL statement [#42135](https://github.com/pingcap/tidb/issues/42135) @[mjonss](https://github.com/mjonss) + - Fix the issue that full index scans might cause errors when prepared plan cache is enabled [#42150](https://github.com/pingcap/tidb/issues/42150) @[fzzf678](https://github.com/fzzf678) + - Fix the issue that IndexMerge might produce incorrect results when prepare plan cache is enabled [#41828](https://github.com/pingcap/tidb/issues/41828) @[qw4990](https://github.com/qw4990) + - Fix the issue that the configuration of `max_prepared_stmt_count` does not take effect [#39735](https://github.com/pingcap/tidb/issues/39735) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that global memory control might incorrectly kill SQL statements with memory usage less than `tidb_server_memory_limit_sess_min_size` [#42662](https://github.com/pingcap/tidb/issues/42662) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that Index Join might cause panic in dynamic trimming mode of partition tables [#40596](https://github.com/pingcap/tidb/issues/40596) @[tiancaiamao](https://github.com/tiancaiamao) + ++ TiKV + + - Fix the issue that TiKV does not correctly parse the `:` character when processing the cgroup path [#14538](https://github.com/tikv/tikv/issues/14538) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + ++ PD + + - Fix the issue that PD might unexpectedly add multiple Learners to a Region [#5786](https://github.com/tikv/pd/issues/5786) @[HunDunDM](https://github.com/HunDunDM) + - Fix the issue that switching placement rule might cause uneven distribution of leaders [#6195](https://github.com/tikv/pd/issues/6195) @[bufferflies](https://github.com/bufferflies) + ++ TiFlash + + - Fix the issue that TiFlash cannot recognize generated columns [#6801](https://github.com/pingcap/tiflash/issues/6801) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that Decimal division does not round up the last digit in certain cases [#7022](https://github.com/pingcap/tiflash/issues/7022) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that Decimal cast rounds up incorrectly in certain cases [#6994](https://github.com/pingcap/tiflash/issues/6994) @[windtalker](https://github.com/windtalker) + - Fix the issue that TopN/Sort operators produce incorrect results after enabling the new collation [#6807](https://github.com/pingcap/tiflash/issues/6807) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue of TiFlash process failures due to TiCDC incompatibility [#7212](https://github.com/pingcap/tiflash/issues/7212) @[hongyunyan](https://github.com/hongyunyan) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the frequency of `resolve lock` is too high when there is no PITR backup task in the TiDB cluster [#40759](https://github.com/pingcap/tidb/issues/40759) @[joccau](https://github.com/joccau) + - Fix the issue of insufficient wait time for splitting Region retry during the PITR recovery process [#42001](https://github.com/pingcap/tidb/issues/42001) @[joccau](https://github.com/joccau) + + + TiCDC + + - Fix the issue that the partition separator does not work when TiCDC replicates data to object storage [#8581](https://github.com/pingcap/tiflow/issues/8581) @[CharlesCheung96](https://github.com/CharlesCheung96) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that table scheduling might cause data loss when TiCDC replicates data to object storage [#8256](https://github.com/pingcap/tiflow/issues/8256) @[zhaoxinyu](https://github.com/zhaoxinyu) + - Fix the issue that the replication gets stuck due to non-reentrant DDL statements [#8662](https://github.com/pingcap/tiflow/issues/8662) @[hicqu](https://github.com/hicqu) + - Fix the issue that TiCDC scaling might cause data loss when TiCDC replicates data to object storage [#8666](https://github.com/pingcap/tiflow/issues/8666) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the memory usage of `db sorter` is not controlled by `cgroup memory limit` [#8588](https://github.com/pingcap/tiflow/issues/8588) @[amyangfei](https://github.com/amyangfei) + - Fix the issue that data loss might occur in special cases during the apply of Redo log [#8591](https://github.com/pingcap/tiflow/issues/8591) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the memory usage of `db sorter` is not controlled by `cgroup memory limit` [#8588](https://github.com/pingcap/tiflow/issues/8588) @[amyangfei](https://github.com/amyangfei) + - Fix the issue that the disorder of `UPDATE` and `INSERT` statements during data replication might cause the `Duplicate entry` error [#8597](https://github.com/pingcap/tiflow/issues/8597) @[sdojjy](https://github.com/sdojjy) + - Fix the abnormal exit issue of the TiCDC service caused by network isolation between PD and TiCDC [#8562](https://github.com/pingcap/tiflow/issues/8562) @[overvenus](https://github.com/overvenus) + - Fix the issue that graceful upgrade for TiCDC clusters fails on Kubernetes [#8484](https://github.com/pingcap/tiflow/issues/8484) @[overvenus](https://github.com/overvenus) + - Fix the issue that the TiCDC server panics when all downstream Kafka servers are unavailable [#8523](https://github.com/pingcap/tiflow/issues/8523) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that restarting the changefeed might cause data loss or that the checkpoint cannot advance [#8242](https://github.com/pingcap/tiflow/issues/8242) @[overvenus](https://github.com/overvenus) diff --git a/releases/release-6.5.3.md b/releases/release-6.5.3.md new file mode 100644 index 0000000000000..f1ca8f2605be4 --- /dev/null +++ b/releases/release-6.5.3.md @@ -0,0 +1,139 @@ +--- +title: TiDB 6.5.3 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 6.5.3. +--- + +# TiDB 6.5.3 Release Notes + +Release date: June 14, 2023 + +TiDB version: 6.5.3 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v6.5/production-deployment-using-tiup) + +## Compatibility changes + +### Behavior changes + +- When processing update event, TiCDC splits an event into delete and insert events if the primary key or non-null unique index value is modified in the event. For more information, see [documentation](/ticdc/ticdc-split-update-behavior.md#transactions-containing-a-single-update-change). + +## Improvements + ++ TiDB + + - Improve the performance of `TRUNCATE` on partitioned tables with Placement Rules [#43070](https://github.com/pingcap/tidb/issues/43070) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Avoid invalid Stale Read retries after resolving locks [#43659](https://github.com/pingcap/tidb/issues/43659) @[you06](https://github.com/you06) + - Reduce latency by using leader read when Stale Read encounters the `DataIsNotReady` error [#765](https://github.com/tikv/client-go/pull/765) @[Tema](https://github.com/Tema) + - Add `Stale Read OPS` and `Stale Read MBps` metrics to track hit rate and traffic when using Stale Read [#43325](https://github.com/pingcap/tidb/issues/43325) @[you06](https://github.com/you06) + ++ TiKV + + - Reduce traffic by using gzip to compress `check_leader` requests [#14839](https://github.com/tikv/tikv/issues/14839) @[cfzjywxk](https://github.com/cfzjywxk) + ++ PD + + - Use a separate gRPC connection for PD leader election to prevent the impact of other requests [#6403](https://github.com/tikv/pd/issues/6403) @[rleungx](https://github.com/rleungx) + ++ Tools + + + TiCDC + + - Optimize the way TiCDC handles DDLs so that DDLs do not block the use of other unrelated DML Events, and reduce memory usage [#8106](https://github.com/pingcap/tiflow/issues/8106) @[asddongmen](https://github.com/asddongmen) + - Optimize the Decoder interface and add a new method `AddKeyValue` [#8861](https://github.com/pingcap/tiflow/issues/8861) @[3AceShowHand](https://github.com/3AceShowHand) + - Optimize the directory structure when DDL events occur in the scenario of replicating data to object storage [#8890](https://github.com/pingcap/tiflow/issues/8890) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support replicating data to the Kafka-on-Pulsar downstream [#8892](https://github.com/pingcap/tiflow/issues/8892) @[hi-rustin](https://github.com/Rustin170506) + - Support using the OAuth protocol for validation when replicating data to Kafka [#8865](https://github.com/pingcap/tiflow/issues/8865) @[hi-rustin](https://github.com/Rustin170506) + - Optimize the way TiCDC handles the `UPDATE` statement during data replication using the Avro or CSV protocol, by splitting `UPDATE` into `DELETE` and `INSERT` statements, so that you can get the old value from the `DELETE` statement [#9086](https://github.com/pingcap/tiflow/issues/9086) @[3AceShowHand](https://github.com/3AceShowHand) + - Add a configuration item `insecure-skip-verify` to control whether to set the authentication algorithm in the scenario of enabling TLS [#8867](https://github.com/pingcap/tiflow/issues/8867) @[hi-rustin](https://github.com/Rustin170506) + - Optimize DDL replication operations to mitigate the impact of DDL operations on downstream latency [#8686](https://github.com/pingcap/tiflow/issues/8686) @[hi-rustin](https://github.com/Rustin170506) + - Optimize the method of setting GC TLS for the upstream when the TiCDC replication task fails [#8403](https://github.com/pingcap/tiflow/issues/8403) @[charleszheng44](https://github.com/charleszheng44) + + + TiDB Binlog + + - Optimize the method of retrieving table information to reduce the initialization time and memory usage of Drainer [#1137](https://github.com/pingcap/tidb-binlog/issues/1137) @[lichunzhu](https://github.com/lichunzhu) + +## Bug fixes + ++ TiDB + + - Fix the issue that the `min, max` query result is incorrect [#43805](https://github.com/pingcap/tidb/issues/43805) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue of incorrect execution plans when pushing down window functions to TiFlash [#43922](https://github.com/pingcap/tidb/issues/43922) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that the query with CTE causes TiDB to hang [#43749](https://github.com/pingcap/tidb/issues/43749) [#36896](https://github.com/pingcap/tidb/issues/36896) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the SQL statement reports the `runtime error: index out of range` error when using the `AES_DECRYPT` expression [#43063](https://github.com/pingcap/tidb/issues/43063) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the `SHOW PROCESSLIST` statement cannot display the TxnStart of the transaction of the statement with a long subquery time [#40851](https://github.com/pingcap/tidb/issues/40851) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that PD isolation might block the running DDL [#44014](https://github.com/pingcap/tidb/issues/44014) [#43755](https://github.com/pingcap/tidb/issues/43755) [#44267](https://github.com/pingcap/tidb/issues/44267) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the TiDB panic issue that occurs when querying union views and temporary tables with `UNION` [#42563](https://github.com/pingcap/tidb/issues/42563) @[lcwangchao](https://github.com/lcwangchao) + - Fix the behavior issue of Placement Rules in partitioned tables, so that the Placement Rules in deleted partitions can be correctly set and recycled [#44116](https://github.com/pingcap/tidb/issues/44116) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that truncating a partition of a partitioned table might cause the Placement Rule of the partition to become invalid [#44031](https://github.com/pingcap/tidb/issues/44031) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that TiCDC might lose some row changes during table renaming [#43338](https://github.com/pingcap/tidb/issues/43338) @[tangenta](https://github.com/tangenta) + - Fix the issue that the DDL job history is lost after importing a table using BR [#43725](https://github.com/pingcap/tidb/issues/43725) @[tangenta](https://github.com/tangenta) + - Fix the issue that `JSON_OBJECT` might report an error in some cases [#39806](https://github.com/pingcap/tidb/issues/39806) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the cluster cannot query some system views in IPv6 environment [#43286](https://github.com/pingcap/tidb/issues/43286) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that when the PD member address changes, allocating ID for the `AUTO_INCREMENT` column will be blocked for a long time [#42643](https://github.com/pingcap/tidb/issues/42643) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB sends duplicate requests to PD during placement rules recycling, causing numerous `full config reset` entries in the PD log [#33069](https://github.com/pingcap/tidb/issues/33069) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `SHOW PRIVILEGES` statement returns an incomplete privilege list [#40591](https://github.com/pingcap/tidb/issues/40591) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that `ADMIN SHOW DDL JOBS LIMIT` returns incorrect results [#42298](https://github.com/pingcap/tidb/issues/42298) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that the `tidb_auth_token` user fails to be created when the password complexity check is enabled [#44098](https://github.com/pingcap/tidb/issues/44098) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue of not finding the partition during inner join in dynamic pruning mode [#43686](https://github.com/pingcap/tidb/issues/43686) @[mjonss](https://github.com/mjonss) + - Fix the issue that the `Data Truncated` warning occurs when executing `MODIFY COLUMN` on a partitioned table [#41118](https://github.com/pingcap/tidb/issues/41118) @[mjonss](https://github.com/mjonss) + - Fix the issue of displaying the incorrect TiDB address in IPv6 environment [#43260](https://github.com/pingcap/tidb/issues/43260) @[nexustar](https://github.com/nexustar) + - Fix the issue that CTE results are incorrect when pushing down predicates [#43645](https://github.com/pingcap/tidb/issues/43645) @[winoros](https://github.com/winoros) + - Fix the issue that incorrect results might be returned when using a common table expression (CTE) in statements with non-correlated subqueries [#44051](https://github.com/pingcap/tidb/issues/44051) @[winoros](https://github.com/winoros) + - Fix the issue that Join Reorder might cause incorrect outer join results [#44314](https://github.com/pingcap/tidb/issues/44314) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that in some extreme cases, when the first statement of a pessimistic transaction is retried, resolving locks on this transaction might affect transaction correctness [#42937](https://github.com/pingcap/tidb/issues/42937) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that in some rare cases, residual pessimistic locks of pessimistic transactions might affect data correctness when GC resolves locks [#43243](https://github.com/pingcap/tidb/issues/43243) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that the scan detail information during the execution of `batch cop` might be inaccurate [#41582](https://github.com/pingcap/tidb/issues/41582) @[you06](https://github.com/you06) + - Fix the issue that TiDB cannot read data updates when Stale Read and `PREPARE` statements are used at the same time [#43044](https://github.com/pingcap/tidb/issues/43044) @[you06](https://github.com/you06) + - Fix the issue that an `assertion failed` error might be mistakenly reported when executing the `LOAD DATA` statement [#43849](https://github.com/pingcap/tidb/issues/43849) @[you06](https://github.com/you06) + - Fix the issue that the coprocessor cannot fall back to the leader when a `region data not ready` error occurs during the use of Stale Read [#43365](https://github.com/pingcap/tidb/issues/43365) @[you06](https://github.com/you06) + ++ TiKV + + - Fix the issue that the peers of the corresponding Region mistakenly hibernate when a TiKV node fails [#14547](https://github.com/tikv/tikv/issues/14547) @[hicqu](https://github.com/hicqu) + - Fix the issue of file handle leakage in Continuous Profiling [#14224](https://github.com/tikv/tikv/issues/14224) @[tabokie](https://github.com/tabokie) + - Fix the issue that PD crash might cause PITR to fail to proceed [#14184](https://github.com/tikv/tikv/issues/14184) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that encryption key ID conflict might cause the deletion of the old keys [#14585](https://github.com/tikv/tikv/issues/14585) @[tabokie](https://github.com/tabokie) + - Fix the issue that autocommit and point get replica read might break linearizability [#14715](https://github.com/tikv/tikv/issues/14715) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the performance degradation issue caused by accumulated lock records when a cluster is upgraded from a previous version to v6.5 or later versions [#14780](https://github.com/tikv/tikv/issues/14780) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that TiDB Lightning might cause SST file leakage [#14745](https://github.com/tikv/tikv/issues/14745) @[YuJuncen](https://github.com/YuJuncen) + - Fix the potential conflict between the encryption key and raft log file deletion that might cause TiKV to fail to start [#14761](https://github.com/tikv/tikv/issues/14761) @[Connor1996](https://github.com/Connor1996) + ++ TiFlash + + - Fix the performance degradation issue of the partition TableScan operator during Region transfer [#7519](https://github.com/pingcap/tiflash/issues/7519) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that a TiFlash query might report an error if the `GENERATED` type field is present along with the `TIMESTAMP` or `TIME` type [#7468](https://github.com/pingcap/tiflash/issues/7468) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that large update transactions might cause TiFlash to repeatedly report errors and restart [#7316](https://github.com/pingcap/tiflash/issues/7316) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that the error "Truncate error cast decimal as decimal" occurs when reading data from TiFlash with the `INSERT SELECT` statement [#7348](https://github.com/pingcap/tiflash/issues/7348) @[windtalker](https://github.com/windtalker) + - Fix the issue that queries might consume more memory than needed when the data on the Join build side is very large and contains many small string type columns [#7416](https://github.com/pingcap/tiflash/issues/7416) @[yibin87](https://github.com/yibin87) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the error message "resolve lock timeout" of BR is misleading when a backup fails, which hides the actual error information [#43236](https://github.com/pingcap/tidb/issues/43236) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix an OOM issue that might occur when there are as many as 50,000 tables [#7872](https://github.com/pingcap/tiflow/issues/7872) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC gets stuck when an OOM occurs in upstream TiDB [#8561](https://github.com/pingcap/tiflow/issues/8561) @[overvenus](https://github.com/overvenus) + - Fix the issue that TiCDC gets stuck when PD fails such as network isolation or PD Owner node reboot [#8808](https://github.com/pingcap/tiflow/issues/8808) [#8812](https://github.com/pingcap/tiflow/issues/8812) [#8877](https://github.com/pingcap/tiflow/issues/8877) @[asddongmen](https://github.com/asddongmen) + - Fix the issue of TiCDC time zone setting [#8798](https://github.com/pingcap/tiflow/issues/8798) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that checkpoint lag increases when one of the upstream TiKV nodes crashes [#8858](https://github.com/pingcap/tiflow/issues/8858) @[hicqu](https://github.com/hicqu) + - Fix the issue that when replicating data to downstream MySQL, a replication error occurs after the `FLASHBACK CLUSTER TO TIMESTAMP` statement is executed in the upstream TiDB [#8040](https://github.com/pingcap/tiflow/issues/8040) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that when replicating data to object storage, the `EXCHANGE PARTITION` operation in the upstream cannot be properly replicated to the downstream [#8914](https://github.com/pingcap/tiflow/issues/8914) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the OOM issue caused by excessive memory usage of the sorter component in some special scenarios [#8974](https://github.com/pingcap/tiflow/issues/8974) @[hicqu](https://github.com/hicqu) + - Fix the issue that when the downstream is Kafka, TiCDC queries the downstream metadata too frequently and causes excessive workload in the downstream [#8957](https://github.com/pingcap/tiflow/issues/8957) [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that when a replication error occurs due to an oversized Kafka message, the message body is recorded in the log [#9031](https://github.com/pingcap/tiflow/issues/9031) @[darraes](https://github.com/darraes) + - Fix the TiCDC node panic that occurs when the downstream Kafka sinks are rolling restarted [#9023](https://github.com/pingcap/tiflow/issues/9023) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that when replicating data to storage services, the JSON file corresponding to downstream DDL statements does not record the default values of table fields [#9066](https://github.com/pingcap/tiflow/issues/9066) @[CharlesCheung96](https://github.com/CharlesCheung96) + + + TiDB Lightning + + - Fix the issue that OOM might occur when importing a wide table [#43728](https://github.com/pingcap/tidb/issues/43728) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue of `write to tikv with no leader returned` when importing a large amount of data [#43055](https://github.com/pingcap/tidb/issues/43055) @[lance6716](https://github.com/lance6716) + - Fix a possible OOM problem when there is an unclosed delimiter in the data file [#40400](https://github.com/pingcap/tidb/issues/40400) @[buchuitoudegou](https://github.com/buchuitoudegou) + - Add a retry mechanism when encountering an `unknown RPC` error during data import [#43291](https://github.com/pingcap/tidb/issues/43291) @[D3Hunter](https://github.com/D3Hunter) + + + TiDB Binlog + + - Fix the issue that TiDB Binlog reports an error when encountering a `CANCELED` DDL statement [#1228](https://github.com/pingcap/tidb-binlog/issues/1228) @[okJiang](https://github.com/okJiang) diff --git a/releases/release-6.5.4.md b/releases/release-6.5.4.md new file mode 100644 index 0000000000000..772a97dd52117 --- /dev/null +++ b/releases/release-6.5.4.md @@ -0,0 +1,201 @@ +--- +title: TiDB 6.5.4 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 6.5.4. +--- + +# TiDB 6.5.4 Release Notes + +Release date: August 28, 2023 + +TiDB version: 6.5.4 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v6.5/production-deployment-using-tiup) + +## Compatibility changes + +- To fix the issue that TiDB consumes too much memory when using `Cursor Fetch` to fetch a large result set, TiDB automatically writes the result set to the disk to release memory [#43233](https://github.com/pingcap/tidb/issues/43233) @[YangKeao](https://github.com/YangKeao) +- Disable periodic compaction of RocksDB by default, so that the default behavior of TiKV RocksDB is now consistent with that in versions before v6.5.0. This change prevents potential performance impact caused by a significant number of compactions after upgrading. In addition, TiKV introduces two new configuration items [`rocksdb.[defaultcf|writecf|lockcf].periodic-compaction-seconds`](https://docs.pingcap.com/tidb/v6.5/tikv-configuration-file#periodic-compaction-seconds-new-in-v654) and [`rocksdb.[defaultcf|writecf|lockcf].ttl`](https://docs.pingcap.com/tidb/v6.5/tikv-configuration-file#ttl-new-in-v654), enabling you to manually configure periodic compaction of RocksDB [#15355](https://github.com/tikv/tikv/issues/15355) @[LykxSassinator](https://github.com/LykxSassinator) + +### Behavior changes + +- For transactions containing multiple changes, if the primary key or non-null unique index value is modified in the update event, TiCDC splits an event into delete and insert events and ensures that all events follow the sequence of delete events preceding insert events. For more information, see [documentation](/ticdc/ticdc-split-update-behavior.md#transactions-containing-multiple-update-changes). + +## Improvements + ++ TiDB + + - Optimize the performance of `LOAD DATA` statements that contain assignment expressions [#46081](https://github.com/pingcap/tidb/issues/46081) @[gengliqi](https://github.com/gengliqi) + - Optimize the performance of reading the dumped chunks from disk [#45125](https://github.com/pingcap/tidb/issues/45125) @[YangKeao](https://github.com/YangKeao) + - Add a `halt-scheduling` configuration item to suspend PD scheduling [#6493](https://github.com/tikv/pd/issues/6493) @[JmPotato](https://github.com/JmPotato) + ++ TiKV + + - Use gzip compression for `check_leader` requests to reduce traffic [#14553](https://github.com/tikv/tikv/issues/14553) @[you06](https://github.com/you06) + - Add the `Max gap of safe-ts` and `Min safe ts region` metrics and introduce the `tikv-ctl get-region-read-progress` command to better observe and diagnose the status of resolved-ts and safe-ts [#15082](https://github.com/tikv/tikv/issues/15082) @[ekexium](https://github.com/ekexium) + - Expose some RocksDB configurations in TiKV that allow users to disable features such as TTL and periodic compaction [#14873](https://github.com/tikv/tikv/issues/14873) @[LykxSassinator](https://github.com/LykxSassinator) + - Avoid holding mutex when writing Titan manifest files to prevent affecting other threads [#15351](https://github.com/tikv/tikv/issues/15351) @[Connor1996](https://github.com/Connor1996) + - Optimize the compaction mechanism: when a Region is split, if there is no key to split, a compaction is triggered to eliminate excessive MVCC versions [#15282](https://github.com/tikv/tikv/issues/15282) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + ++ PD + + - Support blocking the Swagger API by default when the Swagger server is not enabled [#6786](https://github.com/tikv/pd/issues/6786) @[bufferflies](https://github.com/bufferflies) + - Improve the high availability of etcd [#6554](https://github.com/tikv/pd/issues/6554) [#6442](https://github.com/tikv/pd/issues/6442) @[lhy1024](https://github.com/lhy1024) + - Reduce the memory consumption of `GetRegions` requests [#6835](https://github.com/tikv/pd/issues/6835) @[lhy1024](https://github.com/lhy1024) + - Support reusing HTTP connections [#6913](https://github.com/tikv/pd/issues/6913) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Improve TiFlash write performance through IO batch optimization [#7735](https://github.com/pingcap/tiflash/issues/7735) @[lidezhu](https://github.com/lidezhu) + - Improve TiFlash write performance by removing unnecessary fsync operations [#7736](https://github.com/pingcap/tiflash/issues/7736) @[lidezhu](https://github.com/lidezhu) + - Limit the maximum length of the TiFlash coprocessor task queue to avoid excessive queuing of coprocessor tasks, which impacts TiFlash's service availability [#7747](https://github.com/pingcap/tiflash/issues/7747) @[LittleFall](https://github.com/LittleFall) + ++ Tools + + + Backup & Restore (BR) + + - Enhance support for connection reuse by setting `MaxIdleConns` and `MaxIdleConnsPerHost` parameters in the HTTP client [#46011](https://github.com/pingcap/tidb/issues/46011) @[Leavrth](https://github.com/Leavrth) + - Improve fault tolerance of BR when it fails to connect to PD or external S3 storage [#42909](https://github.com/pingcap/tidb/issues/42909) @[Leavrth](https://github.com/Leavrth) + - Add a new restore parameter `WaitTiflashReady`. When this parameter is enabled, the restore operation will be completed after TiFlash replicas are successfully replicated [#43828](https://github.com/pingcap/tidb/issues/43828) [#46302](https://github.com/pingcap/tidb/issues/46302) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Refine the status message when TiCDC retries after a failure [#9483](https://github.com/pingcap/tiflow/issues/9483) @[asddongmen](https://github.com/asddongmen) + - Optimize the way TiCDC handles messages that exceed the limit when synchronizing to Kafka by supporting only sending the primary key to the downstream [#9574](https://github.com/pingcap/tiflow/issues/9574) @[3AceShowHand](https://github.com/3AceShowHand) + - Storage Sink now supports hexadecimal encoding for HEX formatted data, making it compatible with AWS DMS format specifications [#9373](https://github.com/pingcap/tiflow/issues/9373) @[CharlesCheung96](https://github.com/CharlesCheung96) + + + TiDB Data Migration (DM) + + - Support strict optimistic mode for incompatible DDL statements [#9112](https://github.com/pingcap/tiflow/issues/9112) @[GMHDBJD](https://github.com/GMHDBJD) + + + Dumpling + + - Reduce export overhead by skipping querying all databases and tables when exporting data with the `-sql` parameter [#45239](https://github.com/pingcap/tidb/issues/45239) @[lance6716](https://github.com/lance6716) + +## Bug fixes + ++ TiDB + + - Fix the issue that the `index out of range` error might be reported when pushing down the `STREAM_AGG()` operator [#40857](https://github.com/pingcap/tidb/issues/40857) @[Dousir9](https://github.com/Dousir9) + - Fix the issue that TiDB ignores all partition information and creates a non-partitioned table when the `CREATE TABLE` statement contains sub-partition definitions [#41198](https://github.com/pingcap/tidb/issues/41198) [#41200](https://github.com/pingcap/tidb/issues/41200) @[mjonss](https://github.com/mjonss) + - Fix the issue that incorrect `stale_read_ts` setting might cause `PREPARE stmt` to read data incorrectly [#43044](https://github.com/pingcap/tidb/issues/43044) @[you06](https://github.com/you06) + - Fix the issue of possible data race in ActivateTxn [#42092](https://github.com/pingcap/tidb/issues/42092) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that a batch client does not reconnect timely [#44431](https://github.com/pingcap/tidb/issues/44431) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that SQL compile error logs are not redacted [#41831](https://github.com/pingcap/tidb/issues/41831) @[lance6716](https://github.com/lance6716) + - Fix the issue that using CTEs and correlated subqueries simultaneously might result in incorrect query results or panic [#44649](https://github.com/pingcap/tidb/issues/44649) [#38170](https://github.com/pingcap/tidb/issues/38170) [#44774](https://github.com/pingcap/tidb/issues/44774) @[winoros](https://github.com/winoros) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TTL tasks cannot trigger statistics updates in time [#40109](https://github.com/pingcap/tidb/issues/40109) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the GC Resolve Locks step might miss some pessimistic locks [#45134](https://github.com/pingcap/tidb/issues/45134) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that memory leaks and duration continues to increase when connecting to TiDB using the binary protocol and executing a large number of `PREPARE` and `EXECUTE` statements [#44612](https://github.com/pingcap/tidb/issues/44612) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the data length in the `QUERY` column of the `INFORMATION_SCHEMA.DDL_JOBS` table might exceed the column definition [#42440](https://github.com/pingcap/tidb/issues/42440) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the PD OOM issue when there is a large number of Regions but the table ID cannot be pushed down when querying some virtual tables using `Prepare` or `Execute` [#39605](https://github.com/pingcap/tidb/issues/39605) @[djshow832](https://github.com/djshow832) + - Fix the issue that statistics auto-collection might not trigger correctly on a partitioned table after adding a new index to the partitioned table [#41638](https://github.com/pingcap/tidb/issues/41638) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that excessive memory consumption of SQL execution details in statistics causes TiDB OOM in extreme cases [#44047](https://github.com/pingcap/tidb/issues/44047) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that batch coprocessor retry might generate incorrect Region information that causes query failure [#44622](https://github.com/pingcap/tidb/issues/44622) @[windtalker](https://github.com/windtalker) + - Fix the hang-up issue that occurs when queries with `indexMerge` are killed [#45279](https://github.com/pingcap/tidb/issues/45279) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that querying the system table `INFORMATION_SCHEMA.TIKV_REGION_STATUS` returns incorrect results in some cases [#45531](https://github.com/pingcap/tidb/issues/45531) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that query results in MPP mode are incorrect when `tidb_enable_parallel_apply` is enabled [#45299](https://github.com/pingcap/tidb/issues/45299) @[windtalker](https://github.com/windtalker) + - Fix the issue that queries might return incorrect results when `tidb_opt_agg_push_down` is enabled [#44795](https://github.com/pingcap/tidb/issues/44795) @[AilinKid](https://github.com/AilinKid) + - Fix the can't find proper physical plan issue caused by virtual columns [#41014](https://github.com/pingcap/tidb/issues/41014) @[AilinKid](https://github.com/AilinKid) + - Fix the panic issue caused by empty `processInfo` [#43829](https://github.com/pingcap/tidb/issues/43829) @[zimulala](https://github.com/zimulala) + - Fix the issue that the query result of the `SELECT CAST(n AS CHAR)` statement is incorrect when `n` in the statement is a negative number [#44786](https://github.com/pingcap/tidb/issues/44786) @[xhebox](https://github.com/xhebox) + - Fix the issue that when the MySQL Cursor Fetch protocol is used, the memory consumption of result sets might exceed the `tidb_mem_quota_query` limit and causes TiDB OOM. After the fix, TiDB will automatically write result sets to the disk to release memory [#43233](https://github.com/pingcap/tidb/issues/43233) @[YangKeao](https://github.com/YangKeao) + - Fix the `duplicate entry` error that occurs when restoring a table with `AUTO_ID_CACHE=1` using BR [#44716](https://github.com/pingcap/tidb/issues/44716) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `SELECT` statement returns an error for a partitioned table if the table partition definition uses the `FLOOR()` function to round a partitioned column [#42323](https://github.com/pingcap/tidb/issues/42323) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that concurrent view might cause DDL operations to be blocked [#40352](https://github.com/pingcap/tidb/issues/40352) @[zeminzhou](https://github.com/zeminzhou) + - Fix the issue that a statistics collection task fails due to an incorrect `datetime` value [#39336](https://github.com/pingcap/tidb/issues/39336) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that some DDL statements might be stuck for a period after the PD node of a cluster is replaced [#33908](https://github.com/pingcap/tidb/issues/33908) + - Fix the issue that `resolve lock` might hang when there is a sudden change in PD time [#44822](https://github.com/pingcap/tidb/issues/44822) @[zyguan](https://github.com/zyguan) + - Fix the potential data race issue in index scan [#45126](https://github.com/pingcap/tidb/issues/45126) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `FormatSQL()` method cannot properly truncate extremely long SQL statements in input [#44542](https://github.com/pingcap/tidb/issues/44542) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that users can view information in the `INFORMATION_SCHEMA.TIFLASH_REPLICA` table even without permissions [#45320](https://github.com/pingcap/tidb/issues/45320) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that the behavior is inconsistent with MySQL when comparing a `DATETIME` or `TIMESTAMP` column with a number constant [#38361](https://github.com/pingcap/tidb/issues/38361) @[yibin87](https://github.com/yibin87) + - Fix the issue that an error in Index Join might cause the query to get stuck [#45716](https://github.com/pingcap/tidb/issues/45716) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that killing a connection might cause go coroutine leaks [#46034](https://github.com/pingcap/tidb/issues/46034) @[pingyu](https://github.com/pingyu) + - Fix the issue that the `tmp-storage-quota` configuration does not take effect [#45161](https://github.com/pingcap/tidb/issues/45161) [#26806](https://github.com/pingcap/tidb/issues/26806) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that TiFlash replicas might be unavailable when a TiFlash node is down in the cluster [#38484](https://github.com/pingcap/tidb/issues/38484) @[hehechen](https://github.com/hehechen) + - Fix the issue that TiDB crashes due to possible data race when reading and writing `Config.Labels` concurrently [#45561](https://github.com/pingcap/tidb/issues/45561) @[genliqi](https://github.com/gengliqi) + - Fix the issue that the client-go regularly updating `min-resolved-ts` might cause PD OOM when the cluster is large [#46664](https://github.com/pingcap/tidb/issues/46664) @[HuSharp](https://github.com/HuSharp) + ++ TiKV + + - Fix the issue that the `ttl-check-poll-interval` configuration item does not take effect on RawKV API V2 [#15142](https://github.com/tikv/tikv/issues/15142) @[pingyu](https://github.com/pingyu) + - Fix the issue that Online Unsafe Recovery does not abort on timeout [#15346](https://github.com/tikv/tikv/issues/15346) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that Region Merge might be blocked after executing `FLASHBACK` [#15258](https://github.com/tikv/tikv/issues/15258) @[overvenus](https://github.com/overvenus) + - Fix the data inconsistency issue that might occur when one TiKV node is isolated and another node is restarted [#15035](https://github.com/tikv/tikv/issues/15035) @[overvenus](https://github.com/overvenus) + - Fix the issue that the QPS drops to zero in the sync-recover phase under the Data Replication Auto Synchronous mode [#14975](https://github.com/tikv/tikv/issues/14975) @[nolouch](https://github.com/nolouch) + - Fix the issue that encryption might cause data corruption during partial write [#15080](https://github.com/tikv/tikv/issues/15080) @[tabokie](https://github.com/tabokie) + - Fix the issue of heartbeat storms by reducing the number of store heartbeat retries [#15184](https://github.com/tikv/tikv/issues/15184) @[nolouch](https://github.com/nolouch) + - Fix the issue that traffic control might not work when there is a high amount of pending compaction bytes [#14392](https://github.com/tikv/tikv/issues/14392) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that network interruption between PD and TiKV might cause PITR to get stuck [#15279](https://github.com/tikv/tikv/issues/15279) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV might consume more memory when the Old Value feature in TiCDC is enabled [#14815](https://github.com/tikv/tikv/issues/14815) @[YuJuncen](https://github.com/YuJuncen) + ++ PD + + - Fix the issue that when etcd is already started but the client has not yet connected to it, calling the client might cause PD to panic [#6860](https://github.com/tikv/pd/issues/6860) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that a leader cannot exit for a long time [#6918](https://github.com/tikv/pd/issues/6918) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that when the placement rule uses `LOCATION_LABELS`, SQL and the Rule Checker are not compatible [#38605](https://github.com/pingcap/tidb/issues/38605) @[nolouch](https://github.com/nolouch) + - Fix the issue that PD might unexpectedly add multiple Learners to a Region [#5786](https://github.com/tikv/pd/issues/5786) @[HunDunDM](https://github.com/HunDunDM) + - Fix the issue that unhealthy peers cannot be removed when rule checker selects peers [#6559](https://github.com/tikv/pd/issues/6559) @[nolouch](https://github.com/nolouch) + - Fix the issue that failed learner peers in `unsafe recovery` are ignored in `auto-detect` mode [#6690](https://github.com/tikv/pd/issues/6690) @[v01dstar](https://github.com/v01dstar) + ++ TiFlash + + - Fix the issue that queries fail after `fsp` is changed for `DATETIME`, `TIMESTAMP`, or `TIME` data type [#7809](https://github.com/pingcap/tiflash/issues/7809) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash data is inconsistent due to invalid range keys of a region [#7762](https://github.com/pingcap/tiflash/issues/7762) @[lidezhu](https://github.com/lidezhu) + - Fix the issue that when there are multiple HashAgg operators within the same MPP task, the compilation of the MPP task might take an excessively long time, severely affecting query performance [#7810](https://github.com/pingcap/tiflash/issues/7810) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that TiFlash takes too long to restart after using Online Unsafe Recovery [#7671](https://github.com/pingcap/tiflash/issues/7671) @[hongyunyan](https://github.com/hongyunyan) + - Fix the issue that TiFlash rounds the `DECIMAL` result incorrectly when doing division [#6462](https://github.com/pingcap/tiflash/issues/6462) @[LittleFall](https://github.com/LittleFall) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue of restore failures by increasing the default values of the global parameters `TableColumnCountLimit` and `IndexLimit` used by BR to their maximum values [#45793](https://github.com/pingcap/tidb/issues/45793) @[Leavrth](https://github.com/Leavrth) + - Fix the issue of rewrite failures when processing DDL meta information in PITR [#43184](https://github.com/pingcap/tidb/issues/43184) @[Leavrth](https://github.com/Leavrth) + - Fix the issue of panic caused by not checking function returns during PITR execution [#45853](https://github.com/pingcap/tidb/issues/45853) @[Leavrth](https://github.com/Leavrth) + - Fix the issue of obtaining invalid region ID when using S3-compatible storage other than Amazon S3 [#41916](https://github.com/pingcap/tidb/issues/41916) [#42033](https://github.com/pingcap/tidb/issues/42033) @[3pointer](https://github.com/3pointer) + - Fix the potential error in fine-grained backup phase in RawKV mode [#37085](https://github.com/pingcap/tidb/issues/37085) @[pingyu](https://github.com/pingyu) + - Fix the issue that the frequency of `resolve lock` is too high when there is no PITR backup task in the TiDB cluster [#40759](https://github.com/pingcap/tidb/issues/40759) @[joccau](https://github.com/joccau) + - Alleviate the issue that the latency of the PITR log backup progress increases when Region leadership migration occurs [#13638](https://github.com/tikv/tikv/issues/13638) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the issue that the replication task might get stuck when the downstream encounters an error and retries [#9450](https://github.com/pingcap/tiflow/issues/9450) @[hicqu](https://github.com/hicqu) + - Fix the issue that the replication task fails due to short retry intervals when synchronizing to Kafka [#9504](https://github.com/pingcap/tiflow/issues/9504) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that TiCDC might cause synchronization write conflicts when modifying multiple unique key rows in one transaction on the upstream [#9430](https://github.com/pingcap/tiflow/issues/9430) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC might incorrectly synchronize rename DDL operations [#9488](https://github.com/pingcap/tiflow/issues/9488) [#9378](https://github.com/pingcap/tiflow/issues/9378) [#9531](https://github.com/pingcap/tiflow/issues/9531) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the replication task might get stuck when the downstream encounters a short-term failure [#9542](https://github.com/pingcap/tiflow/issues/9542) [#9272](https://github.com/pingcap/tiflow/issues/9272)[#9582](https://github.com/pingcap/tiflow/issues/9582) [#9592](https://github.com/pingcap/tiflow/issues/9592) @[hicqu](https://github.com/hicqu) + - Fix the panic issue that might occur when the TiCDC node status changes [#9354](https://github.com/pingcap/tiflow/issues/9354) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that when Kafka Sink encounters errors it might indefinitely block changefeed progress [#9309](https://github.com/pingcap/tiflow/issues/9309) @[hicqu](https://github.com/hicqu) + - Fix the issue that when the downstream is Kafka, TiCDC queries the downstream metadata too frequently and causes excessive workload in the downstream [#8957](https://github.com/pingcap/tiflow/issues/8957) [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/Rustin170506) + - Fix the data inconsistency issue that might occur when some TiCDC nodes are isolated from the network [#9344](https://github.com/pingcap/tiflow/issues/9344) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the replication task might get stuck when the redo log is enabled and there is an exception downstream [#9172](https://github.com/pingcap/tiflow/issues/9172) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that changefeeds would fail due to the temporary unavailability of PD [#9294](https://github.com/pingcap/tiflow/issues/9294) @[asddongmen](https://github.com/asddongmen) + - Fix the issue of too many downstream logs caused by frequently setting the downstream bidirectional replication-related variables when replicating data to TiDB or MySQL [#9180](https://github.com/pingcap/tiflow/issues/9180) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that Avro protocol incorrectly identifies `Enum` type values [#9259](https://github.com/pingcap/tiflow/issues/9259) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Fix the panic issue when the unique key column name is null [#9247](https://github.com/pingcap/tiflow/issues/9247) @[lance6716](https://github.com/lance6716) + - Fix the deadlock issue that might occur when the validator handles errors incorrectly, and optimize the retry mechanism [#9257](https://github.com/pingcap/tiflow/issues/9257) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that collation is not considered when calculating the causality key [#9489](https://github.com/pingcap/tiflow/issues/9489) @[hihihuhu](https://github.com/hihihuhu) + + + TiDB Lightning + + - Fix the issue that the disk quota check might block when an engine is importing data [#44867](https://github.com/pingcap/tidb/issues/44867) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that checksum reports an error `Region is unavailable` when SSL is enabled on the target cluster [#45462](https://github.com/pingcap/tidb/issues/45462) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that encoding errors cannot be logged correctly [#44321](https://github.com/pingcap/tidb/issues/44321) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that route might panic when importing CSV data [#43284](https://github.com/pingcap/tidb/issues/43284) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that importing table A in logical import mode might mistakenly report that table B does not exist [#44614](https://github.com/pingcap/tidb/issues/44614) @[dsdashun](https://github.com/dsdashun) + - Fix the issue that the data type is wrong when saving `NEXT_GLOBAL_ROW_ID` [#45427](https://github.com/pingcap/tidb/issues/45427) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that checksum still reports errors when `checksum = "optional"` [#45382](https://github.com/pingcap/tidb/issues/45382) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that data import fails when the PD cluster address changes [#43436](https://github.com/pingcap/tidb/issues/43436) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that data import fails when some PD nodes fail [#43400](https://github.com/pingcap/tidb/issues/43400) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that when a table with auto-incremental columns sets `AUTO_ID_CACHE=1`, the base value of the ID allocator is incorrect [#46100](https://github.com/pingcap/tidb/issues/46100) @[D3Hunter](https://github.com/D3Hunter) + + + Dumpling + + - Fix the issue that the exported file is lost due to unprocessed file writer closing error when exporting to Amazon S3 [#45353](https://github.com/pingcap/tidb/issues/45353) @[lichunzhu](https://github.com/lichunzhu) + + + TiDB Binlog + + - Fix the issue that the etcd client does not automatically synchronize the latest node information during initialization [#1236](https://github.com/pingcap/tidb-binlog/issues/1236) @[lichunzhu](https://github.com/lichunzhu) diff --git a/releases/release-6.5.6.md b/releases/release-6.5.6.md new file mode 100644 index 0000000000000..7e2f4fdf0e8aa --- /dev/null +++ b/releases/release-6.5.6.md @@ -0,0 +1,180 @@ +--- +title: TiDB 6.5.6 Release Notes +summary: Learn about the improvements and bug fixes in TiDB 6.5.6. +--- + +# TiDB 6.5.6 Release Notes + +Release date: December 7, 2023 + +TiDB version: 6.5.6 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v6.5/production-deployment-using-tiup) + +## Compatibility changes + +- Prohibit setting [`require_secure_transport`](https://docs.pingcap.com/tidb/v6.5/system-variables#require_secure_transport-new-in-v610) to `ON` in Security Enhanced Mode (SEM) to prevent potential connectivity issues for users [#47665](https://github.com/pingcap/tidb/issues/47665) @[tiancaiamao](https://github.com/tiancaiamao) +- Introduce the [`tidb_opt_enable_hash_join`](https://docs.pingcap.com/tidb/v6.5/system-variables#tidb_opt_enable_hash_join-new-in-v656) system variable to control whether the optimizer selects hash joins for tables [#46695](https://github.com/pingcap/tidb/issues/46695) @[coderplay](https://github.com/coderplay) +- After further testing, the default value of the TiCDC Changefeed configuration item [`case-sensitive`](/ticdc/ticdc-changefeed-config.md) is changed from `true` to `false`. This means that by default, table and database names in the TiCDC configuration file are case-insensitive [#10047](https://github.com/pingcap/tiflow/issues/10047) @[sdojjy](https://github.com/sdojjy) +- TiCDC Changefeed introduces the following new configuration items: + - [`sql-mode`](/ticdc/ticdc-changefeed-config.md): enables you to set the [SQL mode](https://docs.pingcap.com/tidb/v6.5/ticdc-ddl#sql-mode) used by TiCDC to parse DDL statements when TiCDC replicates data [#9876](https://github.com/pingcap/tiflow/issues/9876) @[asddongmen](https://github.com/asddongmen) + - [`encoding-worker-num`](/ticdc/ticdc-changefeed-config.md) and [`flush-worker-num`](/ticdc/ticdc-changefeed-config.md): enables you to set different concurrency parameters for the redo module based on specifications of different machines [#10048](https://github.com/pingcap/tiflow/issues/10048) @[CharlesCheung96](https://github.com/CharlesCheung96) + - [`compression`](/ticdc/ticdc-changefeed-config.md): enables you to configure the compression behavior of redo log files [#10176](https://github.com/pingcap/tiflow/issues/10176) @[sdojjy](https://github.com/sdojjy) + - [`sink.cloud-storage-config`](/ticdc/ticdc-changefeed-config.md): enables you to set the automatic cleanup of historical data when replicating data to object storage [#10109](https://github.com/pingcap/tiflow/issues/10109) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Improvements + ++ TiDB + + - Support the [`FLASHBACK CLUSTER TO TSO`](https://docs.pingcap.com/tidb/v6.5/sql-statement-flashback-cluster) syntax [#48372](https://github.com/pingcap/tidb/issues/48372) @[BornChanger](https://github.com/BornChanger) + ++ TiKV + + - Optimize memory usage of Resolver to prevent OOM [#15458](https://github.com/tikv/tikv/issues/15458) @[overvenus](https://github.com/overvenus) + - Eliminate LRUCache in Router objects to reduce memory usage and prevent OOM [#15430](https://github.com/tikv/tikv/issues/15430) @[Connor1996](https://github.com/Connor1996) + - Add the `alive` and `leak` monitoring dimensions for the `apply_router` and `raft_router` metrics [#15357](https://github.com/tikv/tikv/issues/15357) @[tonyxuqqi](https://github.com/tonyxuqqi) + ++ PD + + - Add monitoring metrics such as `Status` and `Sync Progress` for `DR Auto-Sync` on the Grafana dashboard [#6975](https://github.com/tikv/pd/issues/6975) @[disksing](https://github.com/disksing) + ++ Tools + + + Backup & Restore (BR) + + - During restoring a snapshot backup, BR retries when it encounters certain network errors [#48528](https://github.com/pingcap/tidb/issues/48528) @[Leavrth](https://github.com/Leavrth) + - Introduce a new integration test for Point-In-Time Recovery (PITR) in the `delete range` scenario, enhancing PITR stability [#47738](https://github.com/pingcap/tidb/issues/47738) @[Leavrth](https://github.com/Leavrth) + - Enable automatic retry of Region scatter during snapshot recovery when encountering timeout failures or cancellations of Region scatter [#47236](https://github.com/pingcap/tidb/issues/47236) @[Leavrth](https://github.com/Leavrth) + - BR can pause Region merging by setting the `merge-schedule-limit` configuration to `0` [#7148](https://github.com/tikv/pd/issues/7148) @[BornChanger](https://github.com/3pointer) + + + TiCDC + + - Support making TiCDC Canal-JSON content format [compatible with the content format of the official Canal output](https://docs.pingcap.com/tidb/v6.5/ticdc-canal-json#compatibility-with-the-official-canal) by setting `content-compatible=true` in the `sink-uri` configuration [#10106](https://github.com/pingcap/tiflow/issues/10106) @[3AceShowHand](https://github.com/3AceShowHand) + - Optimize the execution logic of replicating the `ADD INDEX` DDL operations to avoid blocking subsequent DML statements [#9644](https://github.com/pingcap/tiflow/issues/9644) @[sdojjy](https://github.com/sdojjy) + - Reduce the impact of TiCDC incremental scanning on upstream TiKV [#11390](https://github.com/tikv/tikv/issues/11390) @[hicqu](https://github.com/hicqu) + +## Bug fixes + ++ TiDB + + - Fix the issue that the chunk cannot be reused when the HashJoin operator performs probe [#48082](https://github.com/pingcap/tidb/issues/48082) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that `Duplicate entry` might occur when `AUTO_ID_CACHE=1` is set [#46444](https://github.com/pingcap/tidb/issues/46444) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `TIDB_INLJ` hint does not take effect when joining two sub-queries [#46160](https://github.com/pingcap/tidb/issues/46160) @[qw4990](https://github.com/qw4990) + - Fix the issue that DDL operations might get stuck after TiDB is restarted [#46751](https://github.com/pingcap/tidb/issues/46751) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that DDL operations might get permanently blocked due to incorrect MDL handling [#46920](https://github.com/pingcap/tidb/issues/46920) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the results of `MERGE_JOIN` are incorrect [#46580](https://github.com/pingcap/tidb/issues/46580) @[qw4990](https://github.com/qw4990) + - Fix the issue that the Sort operator might cause TiDB to crash during the spill process [#47538](https://github.com/pingcap/tidb/issues/47538) @[windtalker](https://github.com/windtalker) + - Fix the issue that the `cast(col)=range` condition causes FullScan when CAST has no precision loss [#45199](https://github.com/pingcap/tidb/issues/45199) @[AilinKid](https://github.com/AilinKid) + - Fix the panic issue of `batch-client` in `client-go` [#47691](https://github.com/pingcap/tidb/issues/47691) @[crazycs520](https://github.com/crazycs520) + - Prohibit split table operations on non-integer clustered indexes [#47350](https://github.com/pingcap/tidb/issues/47350) @[tangenta](https://github.com/tangenta) + - Fix the incompatibility issue between the behavior of prepared plan cache and non-prepared plan cache during time conversion [#42439](https://github.com/pingcap/tidb/issues/42439) @[qw4990](https://github.com/qw4990) + - Fix the issue that sometimes an index cannot be created for an empty table using ingest mode [#39641](https://github.com/pingcap/tidb/issues/39641) @[tangenta](https://github.com/tangenta) + - Fix the issue of not being able to detect data that does not comply with partition definitions during partition exchange [#46492](https://github.com/pingcap/tidb/issues/46492) @[mjonss](https://github.com/mjonss) + - Fix the issue that `GROUP_CONCAT` cannot parse the `ORDER BY` column [#41986](https://github.com/pingcap/tidb/issues/41986) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that HashCode is repeatedly calculated for deeply nested expressions, which causes high memory usage and OOM [#42788](https://github.com/pingcap/tidb/issues/42788) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that when Aggregation is pushed down through Union in MPP execution plans, the results are incorrect [#45850](https://github.com/pingcap/tidb/issues/45850) @[AilinKid](https://github.com/AilinKid) + - Fix the issue of incorrect memory usage estimation in `INDEX_LOOKUP_HASH_JOIN` [#47788](https://github.com/pingcap/tidb/issues/47788) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that the zip file generated by `plan replayer` cannot be imported back into TiDB [#46474](https://github.com/pingcap/tidb/issues/46474) @[YangKeao](https://github.com/YangKeao) + - Fix the incorrect cost estimation caused by an excessively large `N` in `LIMIT N` [#43285](https://github.com/pingcap/tidb/issues/43285) @[qw4990](https://github.com/qw4990) + - Fix the panic issue that might occur when constructing TopN structure for statistics [#35948](https://github.com/pingcap/tidb/issues/35948) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the result of `COUNT(INT)` calculated by MPP might be incorrect [#48643](https://github.com/pingcap/tidb/issues/48643) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that panic might occur when `tidb_enable_ordered_result_mode` is enabled [#45044](https://github.com/pingcap/tidb/issues/45044) @[qw4990](https://github.com/qw4990) + - Fix the issue that the optimizer mistakenly selects IndexFullScan to reduce sort introduced by window functions [#46177](https://github.com/pingcap/tidb/issues/46177) @[qw4990](https://github.com/qw4990) + - Fix the issue that the result might be incorrect when predicates are pushed down to common table expressions [#47881](https://github.com/pingcap/tidb/issues/47881) @[winoros](https://github.com/winoros) + - Fix the issue that executing `UNION ALL` with the DUAL table as the first subnode might cause an error [#48755](https://github.com/pingcap/tidb/issues/48755) @[winoros](https://github.com/winoros) + - Fix the issue that column pruning can cause panic in specific situations [#47331](https://github.com/pingcap/tidb/issues/47331) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue of possible syntax error when a common table expression (CTE) containing aggregate or window functions is referenced by other recursive CTEs [#47603](https://github.com/pingcap/tidb/issues/47603) [#47711](https://github.com/pingcap/tidb/issues/47711) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that an exception might occur when using the `QB_NAME` hint in a prepared statement [#46817](https://github.com/pingcap/tidb/issues/46817) @[jackysp](https://github.com/jackysp) + - Fix the issue of Goroutine leak when using `AUTO_ID_CACHE=1` [#46324](https://github.com/pingcap/tidb/issues/46324) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB might panic when shutting down [#32110](https://github.com/pingcap/tidb/issues/32110) @[july2993](https://github.com/july2993) + - Fix the issue of not handling locks in the MVCC interface when reading schema diff commit versions from the TiDB schema cache [#48281](https://github.com/pingcap/tidb/issues/48281) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue of duplicate rows in `information_schema.columns` caused by renaming a table [#47064](https://github.com/pingcap/tidb/issues/47064) @[jiyfhust](https://github.com/jiyfhust) + - Fix the bugs in the `LOAD DATA REPLACE INTO` statement [#47995](https://github.com/pingcap/tidb/issues/47995)) @[lance6716](https://github.com/lance6716) + - Fix the issue of `IMPORT INTO` task failure caused by PD leader malfunction for 1 minute [#48307](https://github.com/pingcap/tidb/issues/48307) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue of `ADMIN CHECK` failure caused by creating an index on a date type field [#47426](https://github.com/pingcap/tidb/issues/47426) @[tangenta](https://github.com/tangenta) + - Fix the issue of unsorted row data returned by `TABLESAMPLE` [#48253](https://github.com/pingcap/tidb/issues/48253) @[tangenta](https://github.com/tangenta) + - Fix the TiDB node panic issue that occurs when DDL `jobID` is restored to 0 [#46296](https://github.com/pingcap/tidb/issues/46296) @[jiyfhust](https://github.com/jiyfhust) + ++ TiKV + + - Fix the issue that moving a peer might cause the performance of the Follower Read to deteriorate [#15468](https://github.com/tikv/tikv/issues/15468) @[YuJuncen](https://github.com/YuJuncen) + - Fix the data error of continuously increasing raftstore-applys [#15371](https://github.com/tikv/tikv/issues/15371) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that requests of the TiDB Lightning checksum coprocessor time out when there is online workload [#15565](https://github.com/tikv/tikv/issues/15565) @[lance6716](https://github.com/lance6716) + - Fix security issues by upgrading the version of `lz4-sys` to 1.9.4 [#15621](https://github.com/tikv/tikv/issues/15621) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + - Fix security issues by upgrading the version of `tokio` to 6.5 [#15621](https://github.com/tikv/tikv/issues/15621) @[LykxSassinator](https://github.com/LykxSassinator) + - Fix security issues by removing the `flatbuffer` [#15621](https://github.com/tikv/tikv/issues/15621) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that resolved-ts lag increases when TiKV stores are partitioned [#15679](https://github.com/tikv/tikv/issues/15679) @[hicqu](https://github.com/hicqu) + - Fix the TiKV OOM issue that occurs when restarting TiKV and there are a large number of Raft logs that are not applied [#15770](https://github.com/tikv/tikv/issues/15770) @[overvenus](https://github.com/overvenus) + - Fix the issue that stale peers are retained and block resolved-ts after Regions are merged [#15919](https://github.com/tikv/tikv/issues/15919) @[overvenus](https://github.com/overvenus) + - Fix the issue that the scheduler command variables are incorrect in Grafana on the cloud environment [#15832](https://github.com/tikv/tikv/issues/15832) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that `blob-run-mode` in Titan cannot be updated online [#15978](https://github.com/tikv/tikv/issues/15978) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that TiKV panics due to inconsistent metadata between Regions [#13311](https://github.com/tikv/tikv/issues/13311) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that TiKV panics when the leader is forced to exit during Online Unsafe Recovery [#15629](https://github.com/tikv/tikv/issues/15629) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the joint state of DR Auto-Sync might time out when scaling out [#15817](https://github.com/tikv/tikv/issues/15817) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that TiKV coprocessor might return stale data when removing a Raft peer [#16069](https://github.com/tikv/tikv/issues/16069) @[overvenus](https://github.com/overvenus) + - Fix the issue that resolved-ts might be blocked for 2 hours [#39130](https://github.com/pingcap/tidb/issues/39130) @[overvenus](https://github.com/overvenus) + - Fix the issue that Flashback might get stuck when encountering `notLeader` or `regionNotFound` [#15712](https://github.com/tikv/tikv/issues/15712) @[HuSharp](https://github.com/HuSharp) + ++ PD + + - Fix potential security risks of the plugin directory and files [#7094](https://github.com/tikv/pd/issues/7094) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that modified isolation levels are not synchronized to the default placement rules [#7121](https://github.com/tikv/pd/issues/7121) @[rleungx](https://github.com/rleungx) + - Fix the issue that `evict-leader-scheduler` might lose configuration [#6897](https://github.com/tikv/pd/issues/6897) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the method for counting empty Regions might cause Regions to be unbalanced during the recovery process of BR [#7148](https://github.com/tikv/pd/issues/7148) @[Cabinfever](https://github.com/CabinfeverB) + - Fix the issue that `canSync` and `hasMajority` might be calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode when the configuration of Placement Rules is complex [#7201](https://github.com/tikv/pd/issues/7201) @[disksing](https://github.com/disksing) + - Fix the issue that `available_stores` is calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode [#7221](https://github.com/tikv/pd/issues/7221) @[disksing](https://github.com/disksing) + - Fix the issue that the primary AZ cannot add TiKV nodes when the secondary AZ is down for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode [#7218](https://github.com/tikv/pd/issues/7218) @[disksing](https://github.com/disksing) + - Fix the issue that adding multiple TiKV nodes to a large cluster might cause TiKV heartbeat reporting to become slow or stuck [#7248](https://github.com/tikv/pd/issues/7248) @[rleungx](https://github.com/rleungx) + - Fix the issue that PD might delete normal Peers when TiKV nodes are unavailable [#7249](https://github.com/tikv/pd/issues/7249) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that it takes a long time to switch the leader in DR Auto-Sync mode [#6988](https://github.com/tikv/pd/issues/6988) @[HuSharp](https://github.com/HuSharp) + - Upgrade the version of Gin Web Framework from v1.8.1 to v1.9.1 to fix some security issues [#7438](https://github.com/tikv/pd/issues/7438) @[niubell](https://github.com/niubell) + ++ TiFlash + + - Fix the issue that the `max_snapshot_lifetime` metric is displayed incorrectly on Grafana [#7713](https://github.com/pingcap/tiflash/issues/7713) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that executing the `ALTER TABLE ... EXCHANGE PARTITION ...` statement causes panic [#8372](https://github.com/pingcap/tiflash/issues/8372) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that the memory usage reported by MemoryTracker is inaccurate [#8128](https://github.com/pingcap/tiflash/issues/8128) @[JinheLin](https://github.com/JinheLin) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the log backup might get stuck in some scenarios when backing up large wide tables [#15714](https://github.com/tikv/tikv/issues/15714) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that frequent flushes cause log backup to get stuck [#15602](https://github.com/tikv/tikv/issues/15602) @[3pointer](https://github.com/3pointer) + - Fix the issue that the retry after an EC2 metadata connection reset cause degraded backup and restore performance [#47650](https://github.com/pingcap/tidb/issues/47650) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that running PITR multiple times within 1 minute might cause data loss [#15483](https://github.com/tikv/tikv/issues/15483) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the default values for BR SQL commands and CLI are different, which might cause OOM issues [#48000](https://github.com/pingcap/tidb/issues/48000) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that log backup might panic when the PD owner is transferred [#47533](https://github.com/pingcap/tidb/issues/47533) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that BR generates incorrect URIs for external storage files [#48452](https://github.com/pingcap/tidb/issues/48452) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiCDC + + - Fix the issue that TiCDC server might panic when executing lossy DDL statements in upstream [#9739](https://github.com/pingcap/tiflow/issues/9739) @[hicqu](https://github.com/hicqu) + - Fix the issue that the replication task reports an error when executing `RESUME` with the redo log feature enabled [#9769](https://github.com/pingcap/tiflow/issues/9769) @[hicqu](https://github.com/hicqu) + - Fix the issue that replication lag becomes longer when the TiKV node crashes [#9741](https://github.com/pingcap/tiflow/issues/9741) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that the `WHERE` statement does not use the primary key as the condition when replicating data to TiDB or MySQL [#9988](https://github.com/pingcap/tiflow/issues/9988) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the workload of a replication task is not distributed evenly across TiCDC nodes [#9839](https://github.com/pingcap/tiflow/issues/9839) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the interval between replicating DDL statements is too long when redo log is enabled [#9960](https://github.com/pingcap/tiflow/issues/9960) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the changefeed cannot replicate DML events in bidirectional replication mode if the target table is dropped and then recreated in upstream [#10079](https://github.com/pingcap/tiflow/issues/10079) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the replication lag becomes longer due to too many NFS files when replicating data to an object storage service [#10041](https://github.com/pingcap/tiflow/issues/10041) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the TiCDC server might panic when replicating data to an object storage service [#10137](https://github.com/pingcap/tiflow/issues/10137) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC accesses the invalid old address during PD scaling up and down [#9584](https://github.com/pingcap/tiflow/issues/9584) @[fubinzh](https://github.com/fubinzh) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that fetching wrong memory information might cause OOM issues in some operating systems [#9762](https://github.com/pingcap/tiflow/issues/9762) @[sdojjy](https://github.com/sdojjy) + + + TiDB Data Migration (DM) + + - Fix the issue that DM skips partition DDLs in optimistic mode [#9788](https://github.com/pingcap/tiflow/issues/9788) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that DM cannot properly track upstream table schemas when skipping online DDLs [#9587](https://github.com/pingcap/tiflow/issues/9587) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that replication lag returned by DM keeps growing when a failed DDL is skipped and no subsequent DDLs are executed [#9605](https://github.com/pingcap/tiflow/issues/9605) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that DM skips all DMLs when resuming a task in optimistic mode [#9588](https://github.com/pingcap/tiflow/issues/9588) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Fix the issue that data import fails when encountering the `write to tikv with no leader returned` error [#45673](https://github.com/pingcap/tidb/issues/45673) @[lance6716](https://github.com/lance6716) + - Fix the issue that data import fails because HTTP retry requests do not use the current request content [#47930](https://github.com/pingcap/tidb/issues/47930) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB Lightning gets stuck during `writeToTiKV` [#46321](https://github.com/pingcap/tidb/issues/46321) @[lance6716](https://github.com/lance6716) + - Remove unnecessary `get_regions` calls in physical import mode [#45507](https://github.com/pingcap/tidb/issues/45507) @[mittalrishabh](https://github.com/mittalrishabh) + + + TiDB Binlog + + - Fix the issue that Drainer exits when transporting a transaction greater than 1 GB [#28659](https://github.com/pingcap/tidb/issues/28659) @[jackysp](https://github.com/jackysp) \ No newline at end of file diff --git a/releases/release-6.6.0.md b/releases/release-6.6.0.md new file mode 100644 index 0000000000000..99588e27ee7d0 --- /dev/null +++ b/releases/release-6.6.0.md @@ -0,0 +1,626 @@ +--- +title: TiDB 6.6.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 6.6.0. +--- + +# TiDB 6.6.0 Release Notes + +Release date: February 20, 2023 + +TiDB version: 6.6.0-[DMR](/releases/versioning.md#development-milestone-releases) + +> **Note:** +> +> The TiDB 6.6.0-DMR documentation has been [archived](https://docs-archive.pingcap.com/tidb/v6.6/). PingCAP encourages you to use [the latest LTS version](https://docs.pingcap.com/tidb/stable) of the TiDB database. + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v6.6/quick-start-with-tidb) + +In v6.6.0-DMR, the key new features and improvements are as follows: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeatureDescription
Scalability and Performance
TiKV supports Partitioned Raft KV storage engine (experimental)TiKV introduces the Partitioned Raft KV storage engine, and each Region uses an independent RocksDB instance, which can easily expand the storage capacity of the cluster from TB to PB and provide more stable write latency and stronger scalability.
TiKV supports batch aggregating data requestsThis enhancement significantly reduces total RPCs in TiKV batch-get operations. In situations where data is highly dispersed and the gRPC thread pool has insufficient resources, batching coprocessor requests can improve performance by more than 50%.
TiFlash supports Stale Read and compression exchangeTiFlash supports the stale read feature, which can improve query performance in scenarios where real-time requirements are not restricted. TiFlash supports data compression to improve the efficiency of parallel data exchange, and the overall TPC-H performance improves by 10%, which can save more than 50% of the network usage.
Reliability and availability
Resource control (experimental)Support resource management based on resource groups, which maps database users to the corresponding resource groups and sets quotas for each resource group based on actual needs.
Historical SQL bindingSupport binding historical execution plans and quickly binding execution plans on TiDB Dashboard.
SQL functionalities
Foreign key (experimental)Support MySQL-compatible foreign key constraints to maintain data consistency and improve data quality.
Multi-valued indexes (experimental)Introduce MySQL-compatible multi-valued indexes and enhance the JSON type to improve TiDB's compatibility with MySQL 8.0.
DB operations and observability
DM supports physical import (experimental)TiDB Data Migration (DM) integrates TiDB Lightning's physical import mode to improve the performance of full data migration, with performance being up to 10 times faster.
+ +## Feature details + +### Scalability + +* Support Partitioned Raft KV storage engine (experimental) [#11515](https://github.com/tikv/tikv/issues/11515) [#12842](https://github.com/tikv/tikv/issues/12842) @[busyjay](https://github.com/busyjay) @[tonyxuqqi](https://github.com/tonyxuqqi) @[tabokie](https://github.com/tabokie) @[bufferflies](https://github.com/bufferflies) @[5kbpers](https://github.com/5kbpers) @[SpadeA-Tang](https://github.com/SpadeA-Tang) @[nolouch](https://github.com/nolouch) + + Before TiDB v6.6.0, TiKV's Raft-based storage engine used a single RocksDB instance to store the data of all 'Regions' of the TiKV instance. To support larger clusters more stably, starting from TiDB v6.6.0, a new TiKV storage engine is introduced, which uses multiple RocksDB instances to store TiKV Region data, and the data of each Region is independently stored in a separate RocksDB instance. The new engine can better control the number and level of files in the RocksDB instance, achieve physical isolation of data operations between Regions, and support stably managing more data. You can see it as TiKV managing multiple RocksDB instances through partitioning, which is why the feature is named Partitioned-Raft-KV. The main advantage of this feature is better write performance, faster scaling, and larger volume of data supported with the same hardware. It can also support larger cluster scales. + + Currently, this feature is experimental and not recommended for use in production environments. + + For more information, see [documentation](/partitioned-raft-kv.md). + +* Support the distributed parallel execution framework for DDL operations (experimental) [#37125](https://github.com/pingcap/tidb/issues/37125) @[zimulala](https://github.com/zimulala) + + In previous versions, only one TiDB instance in the entire TiDB cluster was allowed to handle schema change tasks as a DDL owner. To further improve DDL concurrency for large table's DDL operations, TiDB v6.6.0 introduces the distributed parallel execution framework for DDL, through which all TiDB instances in the cluster can concurrently execute the `StateWriteReorganization` phase of the same task to speed up DDL execution. This feature is controlled by the system variable [`tidb_ddl_distribute_reorg`](https://docs.pingcap.com/tidb/v6.6/system-variables#tidb_ddl_distribute_reorg-new-in-v660) and is currently only supported for `Add Index` operations. + +### Performance + +* Support a stable wake-up model for pessimistic lock queues [#13298](https://github.com/tikv/tikv/issues/13298) @[MyonKeminta](https://github.com/MyonKeminta) + + If an application encounters frequent single-point pessimistic lock conflicts, the existing wake-up mechanism cannot guarantee the time for transactions to acquire locks, which causes high long-tail latency and even lock acquisition timeout. Starting from v6.6.0, you can enable a stable wake-up model for pessimistic locks by setting the value of the system variable [`tidb_pessimistic_txn_aggressive_locking`](https://docs.pingcap.com/tidb/v6.6/system-variables#tidb_pessimistic_txn_aggressive_locking-new-in-v660) to `ON`. In this wake-up model, the wake-up sequence of a queue can be strictly controlled to avoid the waste of resources caused by invalid wake-ups. In scenarios with serious lock conflicts, the stable wake-up model can reduce long-tail latency and the P99 response time. + + Tests indicate this reduces tail latency 40-60%. + + For more information, see [documentation](https://docs.pingcap.com/tidb/v6.6/system-variables#tidb_pessimistic_txn_aggressive_locking-new-in-v660). + +* Batch aggregate data requests [#39361](https://github.com/pingcap/tidb/issues/39361) @[cfzjywxk](https://github.com/cfzjywxk) @[you06](https://github.com/you06) + + When TiDB sends a data request to TiKV, TiDB compiles the request into different sub-tasks according to the Region where the data is located, and each sub-task only processes the request of a single Region. When the data to be accessed is highly dispersed, even if the size of the data is not large, many sub-tasks will be generated, which in turn will generate many RPC requests and consume extra time. Starting from v6.6.0, TiDB supports partially merging data requests that are sent to the same TiKV instance, which reduces the number of sub-tasks and the overhead of RPC requests. In the case of high data dispersion and insufficient gRPC thread pool resources, batching requests can improve performance by more than 50%. + + This feature is enabled by default. You can set the batch size of requests using the system variable [`tidb_store_batch_size`](/system-variables.md#tidb_store_batch_size). + +* Remove the limit on `LIMIT` clauses [#40219](https://github.com/pingcap/tidb/issues/40219) @[fzzf678](https://github.com/fzzf678) + + Starting from v6.6.0, TiDB plan cache supports caching execution plans with a variable as the `LIMIT` parameter, such as `LIMIT ?` or `LIMIT 10, ?`. This feature allows more SQL statements to benefit from plan cache, thus improving execution efficiency. Currently, for security considerations, TiDB can only cache execution plans with `?` not greater than 10000. + + For more information, see [documentation](/sql-prepared-plan-cache.md). + +* TiFlash supports data exchange with compression [#6620](https://github.com/pingcap/tiflash/issues/6620) @[solotzg](https://github.com/solotzg) + + To cooperate with multiple nodes for computing, the TiFlash engine needs to exchange data among different nodes. When the size of the data to be exchanged is very large, the performance of data exchange might affect the overall computing efficiency. In v6.6.0, the TiFlash engine introduces a compression mechanism to compress the data that needs to be exchanged when necessary, and then to perform the exchange, thereby improving the efficiency of data exchange. + + For more information, see [documentation](/explain-mpp.md#mpp-version-and-exchange-data-compression). + +* TiFlash supports the Stale Read feature [#4483](https://github.com/pingcap/tiflash/issues/4483) @[hehechen](https://github.com/hehechen) + + The Stale Read feature has been generally available (GA) since v5.1.1, which allows you to read historical data at a specific timestamp or within a specified time range. Stale read can reduce read latency and improve query performance by reading data from local TiKV replicas directly. Before v6.6.0, TiFlash does not support Stale Read. Even if a table has TiFlash replicas, Stale Read can only read its TiKV replicas. + + Starting from v6.6.0, TiFlash supports the Stale Read feature. When you query the historical data of a table using the [`AS OF TIMESTAMP`](/as-of-timestamp.md) syntax or the [`tidb_read_staleness`](/tidb-read-staleness.md) system variable, if the table has a TiFlash replica, the optimizer now can choose to read the corresponding data from the TiFlash replica, thus further improving query performance. + + For more information, see [documentation](/stale-read.md). + +* Support pushing down the `regexp_replace` string function to TiFlash [#6115](https://github.com/pingcap/tiflash/issues/6115) @[xzhangxian1008](https://github.com/xzhangxian1008) + +### Reliability + +* Support resource control based on resource groups (experimental) [#38825](https://github.com/pingcap/tidb/issues/38825) @[nolouch](https://github.com/nolouch) @[BornChanger](https://github.com/BornChanger) @[glorv](https://github.com/glorv) @[tiancaiamao](https://github.com/tiancaiamao) @[Connor1996](https://github.com/Connor1996) @[JmPotato](https://github.com/JmPotato) @[hnes](https://github.com/hnes) @[CabinfeverB](https://github.com/CabinfeverB) @[HuSharp](https://github.com/HuSharp) + + Now you can create resource groups for a TiDB cluster, bind different database users to corresponding resource groups, and set quotas for each resource group according to actual needs. When the cluster resources are limited, all resources used by sessions in the same resource group will be limited to the quota. In this way, even if a resource group is over-consumed, the sessions in other resource groups are not affected. TiDB provides a built-in view of the actual usage of resources on Grafana dashboards, assisting you to allocate resources more rationally. + + The introduction of the resource control feature is a milestone for TiDB. It can divide a distributed database cluster into multiple logical units. Even if an individual unit overuses resources, it does not crowd out the resources needed by other units. + + With this feature, you can: + + - Combine multiple small and medium-sized applications from different systems into a single TiDB cluster. When the workload of an application grows larger, it does not affect the normal operation of other applications. When the system workload is low, busy applications can still be allocated the required system resources even if they exceed the set read and write quotas, so as to achieve the maximum utilization of resources. + - Choose to combine all test environments into a single TiDB cluster, or group the batch tasks that consume more resources into a single resource group. It can improve hardware utilization and reduce operating costs while ensuring that critical applications can always get the necessary resources. + + In addition, the rational use of the resource control feature can reduce the number of clusters, ease the difficulty of operation and maintenance, and save management costs. + + In v6.6, you need to enable both TiDB's global variable [`tidb_enable_resource_control`](/system-variables.md#tidb_enable_resource_control-new-in-v660) and the TiKV configuration item [`resource-control.enabled`](/tikv-configuration-file.md#resource-control) to enable resource control. Currently, the supported quota method is based on "[Request Unit (RU)](/tidb-resource-control.md#what-is-request-unit-ru)". RU is TiDB's unified abstraction unit for system resources such as CPU and IO. + + For more information, see [documentation](/tidb-resource-control.md). + +* Binding historical execution plans is GA [#39199](https://github.com/pingcap/tidb/issues/39199) @[fzzf678](https://github.com/fzzf678) + + In v6.5.0, TiDB extends the binding targets in the [`CREATE [GLOBAL | SESSION] BINDING`](/sql-statements/sql-statement-create-binding.md) statements and supports creating bindings according to historical execution plans. In v6.6.0, this feature is GA. The selection of execution plans is not limited to the current TiDB node. Any historical execution plan generated by any TiDB node can be selected as the target of [SQL binding](/sql-statements/sql-statement-create-binding.md), which further improves the feature usability. + + For more information, see [documentation](/sql-plan-management.md#create-a-binding-according-to-a-historical-execution-plan). + +* Add several optimizer hints [#39964](https://github.com/pingcap/tidb/issues/39964) @[Reminiscent](https://github.com/Reminiscent) + + TiDB adds several optimizer hints in v6.6.0 to control the execution plan selection of `LIMIT` operations. + + - [`ORDER_INDEX()`](/optimizer-hints.md#order_indext1_name-idx1_name--idx2_name-): tells the optimizer to use the specified index, to keep the order of the index when reading data, and generates plans similar to `Limit + IndexScan(keep order: true)`. + - [`NO_ORDER_INDEX()`](/optimizer-hints.md#no_order_indext1_name-idx1_name--idx2_name-): tells the optimizer to use the specified index, not to keep the order of the index when reading data, and generates plans similar to `TopN + IndexScan(keep order: false)`. + + Continuously introducing optimizer hints provides users with more intervention methods, helps solve SQL performance issues, and improves the stability of overall performance. + +* Support dynamically managing the resource usage of DDL operations (experimental) [#38025](https://github.com/pingcap/tidb/issues/38025) @[hawkingrei](https://github.com/hawkingrei) + + TiDB v6.6.0 introduces resource management for DDL operations to reduce the impact of DDL changes on online applications by automatically controlling the CPU usage of these operations. This feature is effective only after the [DDL distributed parallel execution framework](https://docs.pingcap.com/tidb/v6.6/system-variables#tidb_ddl_distribute_reorg-new-in-v660) is enabled. + +### Availability + +* Support configuring `SURVIVAL_PREFERENCE` for [placement rules in SQL](/placement-rules-in-sql.md) [#38605](https://github.com/pingcap/tidb/issues/38605) @[nolouch](https://github.com/nolouch) + + `SURVIVAL_PREFERENCES` provides data survival preference settings to increase the disaster survivability of data. By specifying `SURVIVAL_PREFERENCE`, you can control the following: + + - For TiDB clusters deployed across cloud regions, when a cloud region fails, the specified databases or tables can survive in another cloud region. + - For TiDB clusters deployed in a single cloud region, when an availability zone fails, the specified databases or tables can survive in another availability zone. + + For more information, see [documentation](/placement-rules-in-sql.md#specify-survival-preferences). + +* Support rolling back DDL operations via the `FLASHBACK CLUSTER TO TIMESTAMP` statement [#14045](https://github.com/tikv/tikv/issues/14045) @[Defined2014](https://github.com/Defined2014) @[JmPotato](https://github.com/JmPotato) + + The [`FLASHBACK CLUSTER TO TIMESTAMP`](/sql-statements/sql-statement-flashback-cluster.md) statement supports restoring the entire cluster to a specified point in time within the Garbage Collection (GC) lifetime. In TiDB v6.6.0, this feature adds support for rolling back DDL operations. This can be used to quickly undo a DML or DDL misoperation on a cluster, roll back a cluster within minutes, and roll back a cluster multiple times on the timeline to determine when specific data changes occurred. + + For more information, see [documentation](/sql-statements/sql-statement-flashback-cluster.md). + +### SQL + +* Support MySQL-compatible foreign key constraints (experimental) [#18209](https://github.com/pingcap/tidb/issues/18209) @[crazycs520](https://github.com/crazycs520) + + TiDB v6.6.0 introduces the foreign key constraints feature, which is compatible with MySQL. This feature supports referencing within a table or between tables, constraints validation, and cascade operations. This feature helps to migrate applications to TiDB, maintain data consistency, improve data quality, and facilitate data modeling. + + For more information, see [documentation](/foreign-key.md). + +* Support MySQL-compatible multi-valued indexes (experimental) [#39592](https://github.com/pingcap/tidb/issues/39592) @[xiongjiwei](https://github.com/xiongjiwei) @[qw4990](https://github.com/qw4990) + + TiDB introduces MySQL-compatible multi-valued indexes in v6.6.0. Filtering the values of an array in a JSON column is a common operation, but normal indexes cannot help speed up such an operation. Creating a multi-valued index on an array can greatly improve filtering performance. If an array in the JSON column has a multi-valued index, you can use the multi-valued index to filter the retrieval conditions with `MEMBER OF()`, `JSON_CONTAINS()`, `JSON_OVERLAPS()` functions, thereby reducing much I/O consumption and improving operation speed. + + Introducing multi-valued indexes further enhances TiDB's support for the JSON data type and also improves TiDB's compatibility with MySQL 8.0. + + For more information, see [documentation](/sql-statements/sql-statement-create-index.md#multi-valued-indexes). + +### DB operations + +* Support configuring read-only storage nodes for resource-consuming tasks @[v01dstar](https://github.com/v01dstar) + + In production environments, some read-only operations might consume a large number of resources regularly and affect the performance of the entire cluster, such as backups and large-scale data reading and analysis. TiDB v6.6.0 supports configuring read-only storage nodes for resource-consuming read-only tasks to reduce the impact on the online application. Currently, TiDB, TiSpark, and BR support reading data from read-only storage nodes. You can configure read-only storage nodes according to [steps](/best-practices/readonly-nodes.md#procedures) and specify where data is read through the system variable `tidb_replica_read`, the TiSpark configuration item `spark.tispark.replica_read`, or the br command line argument `--replica-read-label`, to ensure the stability of cluster performance. + + For more information, see [documentation](/best-practices/readonly-nodes.md). + +* Support dynamically modifying `store-io-pool-size` [#13964](https://github.com/tikv/tikv/issues/13964) @[LykxSassinator](https://github.com/LykxSassinator) + + The TiKV configuration item [`raftstore.store-io-pool-size`](/tikv-configuration-file.md#store-io-pool-size-new-in-v530) specifies the allowable number of threads that process Raft I/O tasks, which can be adjusted when tuning TiKV performance. Before v6.6.0, this configuration item cannot be modified dynamically. Starting from v6.6.0, you can modify this configuration without restarting the server, which means more flexible performance tuning. + + For more information, see [documentation](/dynamic-config.md). + +* Support specifying the SQL script executed upon TiDB cluster initialization [#35624](https://github.com/pingcap/tidb/issues/35624) @[morgo](https://github.com/morgo) + + When you start a TiDB cluster for the first time, you can specify the SQL script to be executed by configuring the command line parameter `--initialize-sql-file`. You can use this feature when you need to perform such operations as modifying the value of a system variable, creating a user, or granting privileges. + + For more information, see [documentation](/tidb-configuration-file.md#initialize-sql-file-new-in-v660). + +* TiDB Data Migration (DM) integrates with TiDB Lightning's physical import mode for up to a 10x performance boost for full migration (experimental) @[lance6716](https://github.com/lance6716) + + In v6.6.0, DM full migration capability integrates with physical import mode of TiDB Lightning, which enables DM to improve the performance of full data migration by up to 10 times, greatly reducing the migration time in large data volume scenarios. + + Before v6.6.0, for large data volume scenarios, you were required to configure physical import tasks in TiDB Lightning separately for fast full data migration, and then use DM for incremental data migration, which was a complex configuration. Starting from v6.6.0, you can migrate large data volumes without the need to configure TiDB Lightning tasks; one DM task can accomplish the migration. + + For more information, see [documentation](/dm/dm-precheck.md#check-items-for-physical-import). + +* TiDB Lightning adds a new configuration parameter `"header-schema-match"` to address the issue of mismatched column names between the source file and the target table @[dsdashun](https://github.com/dsdashun) + + In v6.6.0, TiDB Lightning adds a new profile parameter `"header-schema-match"`. The default value is `true`, which means the first row of the source CSV file is treated as the column name, and consistent with that in the target table. If the field name in the CSV table header does not match the column name of the target table, you can set this configuration to `false`. TiDB Lightning will ignore the error and continue to import the data in the order of the columns in the target table. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task). + +* TiDB Lightning supports enabling compressed transfers when sending key-value pairs to TiKV [#41163](https://github.com/pingcap/tidb/issues/41163) @[sleepymole](https://github.com/sleepymole) + + Starting from v6.6.0, TiDB Lightning supports compressing locally encoded and sorted key-value pairs for network transfer when sending them to TiKV, thus reducing the amount of data transferred over the network and lowering the network bandwidth overhead. In the earlier TiDB versions before this feature is supported, TiDB Lightning requires relatively high network bandwidth and incurs high traffic charges in case of large data volumes. + + This feature is disabled by default. To enable it, you can set the `compress-kv-pairs` configuration item of TiDB Lightning to `"gzip"` or `"gz"`. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task). + +* The TiKV-CDC tool is now GA and supports subscribing to data changes of RawKV [#48](https://github.com/tikv/migration/issues/48) @[zeminzhou](https://github.com/zeminzhou) @[haojinming](https://github.com/haojinming) @[pingyu](https://github.com/pingyu) + + TiKV-CDC is a CDC (Change Data Capture) tool for TiKV clusters. TiKV and PD can constitute a KV database when used without TiDB, which is called RawKV. TiKV-CDC supports subscribing to data changes of RawKV and replicating them to a downstream TiKV cluster in real time, thus enabling cross-cluster replication of RawKV. + + For more information, see [documentation](https://tikv.org/docs/latest/concepts/explore-tikv-features/cdc/cdc/). + +* TiCDC supports scaling out a single table on Kafka changefeeds and distributing the changefeed to multiple TiCDC nodes (experimental) [#7720](https://github.com/pingcap/tiflow/issues/7720) @[overvenus](https://github.com/overvenus) + + Before v6.6.0, when a table in the upstream accepts a large amount of writes, the replication capability of this table cannot be scaled out, resulting in an increase in the replication latency. Starting from TiCDC v6.6.0. the changefeed of an upstream table can be distributed to multiple TiCDC nodes in a Kafka sink, which means the replication capability of a single table is scaled out. + + For more information, see [documentation](/ticdc/ticdc-sink-to-kafka.md#scale-out-the-load-of-a-single-large-table-to-multiple-ticdc-nodes). + +* [GORM](https://github.com/go-gorm/gorm) adds TiDB integration tests. Now TiDB is the default database supported by GORM. [#6014](https://github.com/go-gorm/gorm/pull/6014) @[Icemap](https://github.com/Icemap) + + - In v1.4.6, [GORM MySQL driver](https://github.com/go-gorm/mysql) adapts to the `AUTO_RANDOM` attribute of TiDB [#104](https://github.com/go-gorm/mysql/pull/104) + - In v1.4.6, [GORM MySQL driver](https://github.com/go-gorm/mysql) fixes the issue that when connecting to TiDB, the `Unique` attribute of the `Unique` field cannot be modified during `AutoMigrate` [#105](https://github.com/go-gorm/mysql/pull/105) + - [GORM documentation](https://github.com/go-gorm/gorm.io) mentions TiDB as the default database [#638](https://github.com/go-gorm/gorm.io/pull/638) + + For more information, see [GORM documentation](https://gorm.io/docs/index.html). + +### Observability + +* Support quickly creating SQL binding on TiDB Dashboard [#781](https://github.com/pingcap/tidb-dashboard/issues/781) @[YiniXu9506](https://github.com/YiniXu9506) + + TiDB v6.6.0 supports creating SQL binding from statement history, which allows you to quickly bind a SQL statement to a specific plan on TiDB Dashboard. + + By providing a user-friendly interface, this feature simplifies the process of binding plans in TiDB, reduces the operation complexity, and improves the efficiency and user experience of the plan binding process. + + For more information, see [documentation](/dashboard/dashboard-statement-details.md#fast-plan-binding). + +* Add warning for caching execution plans @[qw4990](https://github.com/qw4990) + + When an execution plan cannot be cached, TiDB indicates the reason in warning to make diagnostics easier. For example: + + ```sql + mysql> PREPARE st FROM 'SELECT * FROM t WHERE a SET @a='1'; + Query OK, 0 rows affected (0.00 sec) + + mysql> EXECUTE st USING @a; + Empty set, 1 warning (0.01 sec) + + mysql> SHOW WARNINGS; + +---------+------+----------------------------------------------+ + | Level | Code | Message | + +---------+------+----------------------------------------------+ + | Warning | 1105 | skip plan-cache: '1' may be converted to INT | + +---------+------+----------------------------------------------+ + ``` + + In the preceding example, the optimizer converts a non-INT type to an INT type, and the execution plan might change with the change of the parameter, so TiDB does not cache the plan. + + For more information, see [documentation](/sql-prepared-plan-cache.md#diagnostics-of-prepared-plan-cache). + +* Add a `Warnings` field to the slow query log [#39893](https://github.com/pingcap/tidb/issues/39893) @[time-and-fate](https://github.com/time-and-fate) + + TiDB v6.6.0 adds a `Warnings` field to the slow query log to help diagnose performance issues. This field records warnings generated during the execution of a slow query. You can also view the warnings on the slow query page of TiDB Dashboard. + + For more information, see [documentation](/identify-slow-queries.md). + +* Automatically capture the generation of SQL execution plans [#38779](https://github.com/pingcap/tidb/issues/38779) @[Yisaer](https://github.com/Yisaer) + + In the process of troubleshooting execution plan issues, `PLAN REPLAYER` can help preserve the scene and improve the efficiency of diagnosis. However, in some scenarios, the generation of some execution plans cannot be reproduced freely, which makes the diagnosis work more difficult. + + To address such issues, in TiDB v6.6.0, `PLAN REPLAYER` extends the capability of automatic capture. With the `PLAN REPLAYER CAPTURE` command, you can register the target SQL statement in advance and also specify the target execution plan at the same time. When TiDB detects the SQL statement or the execution plan that matches the registered target, it automatically generates and packages the `PLAN REPLAYER` information. When the execution plan is unstable, this feature can improve diagnostic efficiency. + + To use this feature, set the value of [`tidb_enable_plan_replayer_capture`](/system-variables.md#tidb_enable_plan_replayer_capture) to `ON`. + + For more information, see [documentation](/sql-plan-replayer.md#use-plan-replayer-capture). + +* Support persisting statements summary (experimental) [#40812](https://github.com/pingcap/tidb/issues/40812) @[mornyx](https://github.com/mornyx) + + Before v6.6.0, statements summary data is kept in memory and would be lost upon a TiDB server restart. Starting from v6.6.0, TiDB supports enabling statements summary persistence, which allows historical data to be written to disks on a regular basis. In the meantime, the result of queries on system tables will derive from disks, instead of memory. After TiDB restarts, all historical data remains available. + + For more information, see [documentation](/statement-summary-tables.md#persist-statements-summary). + +### Security + +* TiFlash supports automatic rotations of TLS certificates [#5503](https://github.com/pingcap/tiflash/issues/5503) @[ywqzzy](https://github.com/ywqzzy) + + In v6.6.0, TiDB supports automatic rotations of TiFlash TLS certificates. For a TiDB cluster with encrypted data transmission between components enabled, when a TLS certificate of TiFlash expires and needs to be reissued with a new one, the new TiFlash TLS certificate can be automatically loaded without restarting the TiDB cluster. In addition, the rotation of a TLS certificate between components within a TiDB cluster does not affect the use of the TiDB cluster, which ensures high availability of the cluster. + + For more information, see [documentation](/enable-tls-between-components.md). + +* TiDB Lightning supports accessing Amazon S3 data via AWS IAM role keys and session tokens [#40750](https://github.com/pingcap/tidb/issues/40750) @[okJiang](https://github.com/okJiang) + + Before v6.6.0, TiDB Lightning only supports accessing S3 data via AWS IAM **user's access keys** (each access key consists of an access key ID and a secret access key) so you cannot use a temporary session token to access S3 data. Starting from v6.6.0, TiDB Lightning supports accessing S3 data via AWS IAM **role's access keys + session tokens** as well to improve the data security. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-data-source.md#import-data-from-amazon-s3). + +### Telemetry + +- Starting from February 20, 2023, the [telemetry feature](/telemetry.md) is disabled by default in new versions of TiDB and TiDB Dashboard (including v6.6.0). If you upgrade from a previous version that uses the default telemetry configuration, the telemetry feature is disabled after the upgrade. For the specific versions, see [TiDB Release Timeline](/releases/release-timeline.md). +- Starting from v1.11.3, the telemetry feature is disabled by default in newly deployed TiUP. If you upgrade from a previous version of TiUP to v1.11.3 or a later version, the telemetry feature keeps the same status as before the upgrade. + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v6.5.0 to the current version (v6.6.0). If you are upgrading from v6.4.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### MySQL compatibility + +* Support MySQL-compatible foreign key constraints (experimental) [#18209](https://github.com/pingcap/tidb/issues/18209) @[crazycs520](https://github.com/crazycs520) + + For more information, see the [SQL](#sql) section in this document and [documentation](/foreign-key.md). + +* Support the MySQL-compatible multi-valued indexes (experimental) [#39592](https://github.com/pingcap/tidb/issues/39592) @[xiongjiwei](https://github.com/xiongjiwei) @[qw4990](https://github.com/qw4990) + + For more information, see the [SQL](#sql) section in this document and [documentation](/sql-statements/sql-statement-create-index.md#multi-valued-indexes). + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| `tidb_enable_amend_pessimistic_txn` | Deleted | Starting from v6.5.0, this variable is deprecated. Starting from v6.6.0, this variable and the `AMEND TRANSACTION` feature are deleted. TiDB will use [meta lock](/metadata-lock.md) to avoid the `Information schema is changed` error. | +| `tidb_enable_concurrent_ddl` | Deleted | This variable controls whether to allow TiDB to use concurrent DDL statements. When this variable is disabled, TiDB uses the old DDL execution framework, which provides limited support for concurrent DDL execution. Starting from v6.6.0, this variable is deleted and TiDB no longer supports the old DDL execution framework. | +| `tidb_ttl_job_run_interval` | Deleted | This variable is used to control the scheduling interval of TTL jobs in the background. Starting from v6.6.0, this variable is deleted, because TiDB provides the `TTL_JOB_INTERVAL` attribute for every table to control the TTL runtime, which is more flexible than `tidb_ttl_job_run_interval`. | +| [`foreign_key_checks`](/system-variables.md#foreign_key_checks) | Modified | This variable controls whether to enable the foreign key constraint check. The default value changes from `OFF` to `ON`, which means enabling the foreign key check by default. | +| [`tidb_enable_foreign_key`](/system-variables.md#tidb_enable_foreign_key-new-in-v630) | Modified | This variable controls whether to enable the foreign key feature. The default value changes from `OFF` to `ON`, which means enabling foreign key by default. | +| `tidb_enable_general_plan_cache` | Modified | This variable controls whether to enable General Plan Cache. Starting from v6.6.0, this variable is renamed to [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache). | +| [`tidb_enable_historical_stats`](/system-variables.md#tidb_enable_historical_stats) | Modified | This variable controls whether to enable historical statistics. The default value changes from `OFF` to `ON`, which means that historical statistics are enabled by default. | +| [`tidb_enable_telemetry`](/system-variables.md#tidb_enable_telemetry-new-in-v402) | Modified | The default value changes from `ON` to `OFF`, which means that telemetry is disabled by default in TiDB. | +| `tidb_general_plan_cache_size` | Modified | This variable controls the maximum number of execution plans that can be cached by General Plan Cache. Starting from v6.6.0, this variable is renamed to [`tidb_non_prepared_plan_cache_size`](/system-variables.md#tidb_non_prepared_plan_cache_size). | +| [`tidb_replica_read`](/system-variables.md#tidb_replica_read-new-in-v40) | Modified | A new value option `learner` is added for this variable to specify the learner replicas with which TiDB reads data from read-only nodes. | +| [`tidb_replica_read`](/system-variables.md#tidb_replica_read-new-in-v40) | Modified | A new value option `prefer-leader` is added for this variable to improve the overall read availability of TiDB clusters. When this option is set, TiDB prefers to read from the leader replica. When the performance of the leader replica significantly decreases, TiDB automatically reads from follower replicas. | +| [`tidb_store_batch_size`](/system-variables.md#tidb_store_batch_size) | Modified | This variable controls the batch size of the Coprocessor Tasks of the `IndexLookUp` operator. `0` means to disable batch. Starting from v6.6.0, the default value is changed from `0` to `4`, which means 4 Coprocessor tasks will be batched into one task for each batch of requests. | +| [`mpp_exchange_compression_mode`](/system-variables.md#mpp_exchange_compression_mode-new-in-v660) | Newly added | This variable specifies the data compression mode of the MPP Exchange operator. It takes effect when TiDB selects the MPP execution plan with the version number `1`. The default value `UNSPECIFIED` means that TiDB automatically selects the `FAST` compression mode. | +| [`mpp_version`](/system-variables.md#mpp_version-new-in-v660) | Newly added | This variable specifies the version of the MPP execution plan. After a version is specified, TiDB selects the specified version of the MPP execution plan. The default value `UNSPECIFIED` means that TiDB automatically selects the latest version `1`. | +| [`tidb_ddl_distribute_reorg`](https://docs.pingcap.com/tidb/v6.6/system-variables#tidb_ddl_distribute_reorg-new-in-v660) | Newly added | This variable controls whether to enable distributed execution of the DDL reorg phase to accelerate this phase. The default value `OFF` means not to enable distributed execution of the DDL reorg phase by default. Currently, this variable takes effect only for `ADD INDEX`. | +| [`tidb_enable_historical_stats_for_capture`](/system-variables.md#tidb_enable_historical_stats_for_capture) | Newly added | This variable controls whether the information captured by `PLAN REPLAYER CAPTURE` includes historical statistics by default. The default value `OFF` means that historical statistics are not included by default. | +| [`tidb_enable_plan_cache_for_param_limit`](/system-variables.md#tidb_enable_plan_cache_for_param_limit-new-in-v660) | Newly added | This variable controls whether Prepared Plan Cache caches execution plans that contain `COUNT` after `Limit`. The default value is `ON`, which means Prepared Plan Cache supports caching such execution plans. Note that Prepared Plan Cache does not support caching execution plans with a `COUNT` condition that counts a number greater than 10000. | +| [`tidb_enable_plan_replayer_capture`](/system-variables.md#tidb_enable_plan_replayer_capture) | Newly added | This variable controls whether to enable the [`PLAN REPLAYER CAPTURE` feature](/sql-plan-replayer.md#use-plan-replayer-capture-to-capture-target-plans). The default value `OFF` means to disable the `PLAN REPLAYER CAPTURE` feature. | +| [`tidb_enable_resource_control`](/system-variables.md#tidb_enable_resource_control-new-in-v660) | Newly added | This variable controls whether to enable the resource control feature. The default value is `OFF`. When this variable is set to `ON`, the TiDB cluster supports resource isolation of applications based on resource groups. | +| [`tidb_historical_stats_duration`](/system-variables.md#tidb_historical_stats_duration-new-in-v660) | Newly added | This variable controls how long the historical statistics are retained in storage. The default value is 7 days. | +| [`tidb_index_join_double_read_penalty_cost_rate`](/system-variables.md#tidb_index_join_double_read_penalty_cost_rate-new-in-v660) | Newly added | This variable controls whether to add some penalty cost to the selection of index join. The default value `0` means that this feature is disabled by default. | +| [`tidb_pessimistic_txn_aggressive_locking`](https://docs.pingcap.com/tidb/v6.6/system-variables#tidb_pessimistic_txn_aggressive_locking-new-in-v660) | Newly added | This variable controls whether to use enhanced pessimistic locking wake-up model for pessimistic transactions. The default value `OFF` means not to use such a wake-up model for pessimistic transactions by default. | +| [`tidb_stmt_summary_enable_persistent`](/system-variables.md#tidb_stmt_summary_enable_persistent-new-in-v660) | Newly added | This variable is read-only. It controls whether to enable [statements summary persistence](/statement-summary-tables.md#persist-statements-summary). The value of this variable is the same as that of the configuration item [`tidb_stmt_summary_enable_persistent`](/tidb-configuration-file.md#tidb_stmt_summary_enable_persistent-new-in-v660). | +| [`tidb_stmt_summary_filename`](/system-variables.md#tidb_stmt_summary_filename-new-in-v660) | Newly added | This variable is read-only. It specifies the file to which persistent data is written when [statements summary persistence](/statement-summary-tables.md#persist-statements-summary) is enabled. The value of this variable is the same as that of the configuration item [`tidb_stmt_summary_filename`](/tidb-configuration-file.md#tidb_stmt_summary_filename-new-in-v660). | +| [`tidb_stmt_summary_file_max_backups`](/system-variables.md#tidb_stmt_summary_file_max_backups-new-in-v660) | Newly added | This variable is read-only. It specifies the maximum number of data files that can be persisted when [statements summary persistence](/statement-summary-tables.md#persist-statements-summary) is enabled. The value of this variable is the same as that of the configuration item [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660). | +| [`tidb_stmt_summary_file_max_days`](/system-variables.md#tidb_stmt_summary_file_max_days-new-in-v660) | Newly added | This variable is read-only. It specifies the maximum number of days to keep persistent data files when [statements summary persistence](/statement-summary-tables.md#persist-statements-summary) is enabled. The value of this variable is the same as that of the configuration item [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660). | +| [`tidb_stmt_summary_file_max_size`](/system-variables.md#tidb_stmt_summary_file_max_size-new-in-v660) | Newly added | This variable is read-only. It specifies the maximum size of a persistent data file when [statements summary persistence](/statement-summary-tables.md#persist-statements-summary) is enabled. The value of this variable is the same as that of the configuration item [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660). | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiKV | `rocksdb.enable-statistics` | Deleted | This configuration item specifies whether to enable RocksDB statistics. Starting from v6.6.0, this item is deleted. RocksDB statistics are enabled for all clusters by default to help diagnostics. For details, see [#13942](https://github.com/tikv/tikv/pull/13942). | +| TiKV | `raftdb.enable-statistics` | Deleted | This configuration item specifies whether to enable Raft RocksDB statistics. Starting from v6.6.0, this item is deleted. Raft RocksDB statistics are enabled for all clusters by default to help diagnostics. For details, see [#13942](https://github.com/tikv/tikv/pull/13942). | +| TiKV | `storage.block-cache.shared` | Deleted | Starting from v6.6.0, this configuration item is deleted, and the block cache is enabled by default and cannot be disabled. For details, see [#12936](https://github.com/tikv/tikv/issues/12936). | +| DM | `on-duplicate` | Deleted | This configuration item controls the methods to resolve conflicts during the full import phase. In v6.6.0, new configuration items `on-duplicate-logical` and `on-duplicate-physical` are introduced to replace `on-duplicate`. | +| TiDB | [`enable-telemetry`](/tidb-configuration-file.md#enable-telemetry-new-in-v402) | Modified | Starting from v6.6.0, the default value changes from `true` to `false`, which means that telemetry is disabled by default in TiDB. | +| TiKV | [`rocksdb.defaultcf.block-size`](/tikv-configuration-file.md#block-size) and [`rocksdb.writecf.block-size`](/tikv-configuration-file.md#block-size) | Modified | The default values change from `64K` to `32K`. | +| TiKV | [`rocksdb.defaultcf.block-cache-size`](/tikv-configuration-file.md#block-cache-size), [`rocksdb.writecf.block-cache-size`](/tikv-configuration-file.md#block-cache-size), [`rocksdb.lockcf.block-cache-size`](/tikv-configuration-file.md#block-cache-size) | Deprecated | Starting from v6.6.0, these configuration items are deprecated. For details, see [#12936](https://github.com/tikv/tikv/issues/12936). | +| PD | [`enable-telemetry`](/pd-configuration-file.md#enable-telemetry) | Modified | Starting from v6.6.0, the default value changes from `true` to `false`, which means that telemetry is disabled by default in TiDB Dashboard. | +| DM | [`import-mode`](/dm/task-configuration-file-full.md) | Modified | The possible values of this configuration item are changed from `"sql"` and `"loader"` to `"logical"` and `"physical"`. The default value is `"logical"`, which means using TiDB Lightning's logical import mode to import data. | +| TiFlash | [`profile.default.max_memory_usage_for_all_queries`](/tiflash/tiflash-configuration.md#configure-the-tiflashtoml-file) | Modified | Specifies the memory usage limit for the generated intermediate data in all queries. Starting from v6.6.0, the default value changes from `0` to `0.8`, which means the limit is 80% of the total memory. | +| TiCDC | [`consistent.storage`](/ticdc/ticdc-sink-to-mysql.md#prerequisites) | Modified | This configuration item specifies the path under which redo log backup is stored. Two more value options are added for `scheme`, GCS, and Azure. | +| TiDB | [`initialize-sql-file`](/tidb-configuration-file.md#initialize-sql-file-new-in-v660) | Newly added | This configuration item specifies the SQL script to be executed when the TiDB cluster is started for the first time. The default value is empty. | +| TiDB | [`tidb_stmt_summary_enable_persistent`](/tidb-configuration-file.md#tidb_stmt_summary_enable_persistent-new-in-v660) | Newly added | This configuration item controls whether to enable statements summary persistence. The default value is `false`, which means this feature is not enabled by default. | +| TiDB | [`tidb_stmt_summary_file_max_backups`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_backups-new-in-v660) | Newly added | When statements summary persistence is enabled, this configuration specifies the maximum number of data files that can be persisted. `0` means no limit on the number of files. | +| TiDB | [`tidb_stmt_summary_file_max_days`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_days-new-in-v660) | Newly added | When statements summary persistence is enabled, this configuration specifies the maximum number of days to keep persistent data files. | +| TiDB | [`tidb_stmt_summary_file_max_size`](/tidb-configuration-file.md#tidb_stmt_summary_file_max_size-new-in-v660) | Newly added | When statements summary persistence is enabled, this configuration specifies the maximum size of a persistent data file (in MiB). | +| TiDB | [`tidb_stmt_summary_filename`](/tidb-configuration-file.md#tidb_stmt_summary_filename-new-in-v660) | Newly added | When statements summary persistence is enabled, this configuration specifies the file to which persistent data is written. | +| TiKV | [`resource-control.enabled`](/tikv-configuration-file.md#resource-control) | Newly added | Whether to enable scheduling for user foreground read/write requests according to the Request Unit (RU) of the corresponding resource groups. The default value is `false`, which means to disable scheduling according to the RU of the corresponding resource groups. | +| TiKV | [`storage.engine`](/tikv-configuration-file.md#engine-new-in-v660) | Newly added | This configuration item specifies the type of the storage engine. Value options are `"raft-kv"` and `"partitioned-raft-kv"`. This configuration item can only be specified when creating a cluster and cannot be modified once being specified. | +| TiKV | [`rocksdb.write-buffer-flush-oldest-first`](/tikv-configuration-file.md#write-buffer-flush-oldest-first-new-in-v660) | Newly added | This configuration item specifies the flush strategy used when the memory usage of `memtable` of the current RocksDB reaches the threshold. | +| TiKV | [`rocksdb.write-buffer-limit`](/tikv-configuration-file.md#write-buffer-limit-new-in-v660) | Newly added | This configuration item specifies the limit on total memory used by `memtable` of all RocksDB instances in a single TiKV. The default value is 25% of the total machine memory. | +| PD | [`pd-server.enable-gogc-tuner`](/pd-configuration-file.md#enable-gogc-tuner-new-in-v660) | Newly added | This configuration item controls whether to enable the GOGC tuner, which is disabled by default. | +| PD | [`pd-server.gc-tuner-threshold`](/pd-configuration-file.md#gc-tuner-threshold-new-in-v660) | Newly added | This configuration item specifies the maximum memory threshold ratio for tuning GOGC. The default value is `0.6`. | +| PD | [`pd-server.server-memory-limit-gc-trigger`](/pd-configuration-file.md#server-memory-limit-gc-trigger-new-in-v660) | Newly added | This configuration item specifies the threshold ratio at which PD tries to trigger GC. The default value is `0.7`. | +| PD | [`pd-server.server-memory-limit`](/pd-configuration-file.md#server-memory-limit-new-in-v660) | Newly added | This configuration item specifies the memory limit ratio for a PD instance. The value `0` means no memory limit. | +| TiCDC | [`scheduler.region-per-span`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | This configuration item controls whether to split a table into multiple replication ranges based on the number of Regions, and these ranges can be replicated by multiple TiCDC nodes. The default value is `50000`. | +| TiDB Lightning | [`compress-kv-pairs`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Newly added | This configuration item controls whether to enable compression when sending KV pairs to TiKV in the physical import mode. The default value is empty, meaning that the compression is not enabled. | +| DM | [`checksum-physical`](/dm/task-configuration-file-full.md) | Newly added | This configuration item controls whether DM performs `ADMIN CHECKSUM TABLE ` for each table to verify data integrity after the import. The default value is `"required"`, which performs admin checksum after the import. If checksum fails, DM pauses the task and you need to manually handle the failure. | +| DM | [`disk-quota-physical`](/dm/task-configuration-file-full.md) | Newly added | This configuration item sets the disk quota. It corresponds to the [`disk-quota` configuration](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#configure-disk-quota-new-in-v620) of TiDB Lightning. | +| DM | [`on-duplicate-logical`](/dm/task-configuration-file-full.md) | Newly added | This configuration item controls how DM resolves conflicting data in the logical import mode. The default value is `"replace"`, which means using the new data to replace the existing data. | +| DM | [`on-duplicate-physical`](/dm/task-configuration-file-full.md) | Newly added | This configuration item controls how DM resolves conflicting data in the physical import mode. The default value is `"none"`, which means not resolving conflicting data. `"none"` has the best performance, but might lead to inconsistent data in the downstream database. | +| DM | [`sorting-dir-physical`](/dm/task-configuration-file-full.md) | Newly added | This configuration item specifies the directory used for local KV sorting in the physical import mode. The default value is the same as the `dir` configuration. | +| sync-diff-inspector | [`skip-non-existing-table`](/sync-diff-inspector/sync-diff-inspector-overview.md#configuration-file-description) | Newly added | This configuration item controls whether to skip checking upstream and downstream data consistency when tables in the downstream do not exist in the upstream. | +| TiSpark | [`spark.tispark.replica_read`](/tispark-overview.md#tispark-configurations) | Newly added | This configuration item controls the type of replicas to be read. The value options are `leader`, `follower`, and `learner`. | +| TiSpark | [`spark.tispark.replica_read.label`](/tispark-overview.md#tispark-configurations) | Newly added | This configuration item is used to set labels for the target TiKV node. | + +### Others + +- Support dynamically modifying [`store-io-pool-size`](/tikv-configuration-file.md#store-io-pool-size-new-in-v530). This facilitates more flexible TiKV performance tuning. +- Remove the limit on `LIMIT` clauses, thus improving the execution performance. +- Starting from v6.6.0, BR does not support restoring data to clusters earlier than v6.1.0. +- Starting from v6.6.0, TiDB no longer supports modifying column types on partitioned tables because of potential correctness issues. + +## Improvements + ++ TiDB + + - Improve the scheduling mechanism of TTL background cleaning tasks to allow the cleaning task of a single table to be split into several sub-tasks and scheduled to run on multiple TiDB nodes simultaneously [#40361](https://github.com/pingcap/tidb/issues/40361) @[YangKeao](https://github.com/YangKeao) + - Optimize the column name display of the result returned by running multi-statements after setting a non-default delimiter [#39662](https://github.com/pingcap/tidb/issues/39662) @[mjonss](https://github.com/mjonss) + - Optimize the execution efficiency of statements after warning messages are generated [#39702](https://github.com/pingcap/tidb/issues/39702) @[tiancaiamao](https://github.com/tiancaiamao) + - Support distributed data backfill for `ADD INDEX` (experimental) [#37119](https://github.com/pingcap/tidb/issues/37119) @[zimulala](https://github.com/zimulala) + - Support using `CURDATE()` as the default value of a column [#38356](https://github.com/pingcap/tidb/issues/38356) @[CbcWestwolf](https://github.com/CbcWestwolf) + - `partial order prop push down` now supports the LIST-type partitioned tables [#40273](https://github.com/pingcap/tidb/issues/40273) @[winoros](https://github.com/winoros) + - Add error messages for conflicts between optimizer hints and execution plan bindings [#40910](https://github.com/pingcap/tidb/issues/40910) @[Reminiscent](https://github.com/Reminiscent) + - Optimize the plan cache strategy to avoid non-optimal plans when using plan cache in some scenarios [#40312](https://github.com/pingcap/tidb/pull/40312) [#40218](https://github.com/pingcap/tidb/pull/40218) [#40280](https://github.com/pingcap/tidb/pull/40280) [#41136](https://github.com/pingcap/tidb/pull/41136) [#40686](https://github.com/pingcap/tidb/pull/40686) @[qw4990](https://github.com/qw4990) + - Clear expired region cache regularly to avoid memory leak and performance degradation [#40461](https://github.com/pingcap/tidb/issues/40461) @[sticnarf](https://github.com/sticnarf) + - `MODIFY COLUMN` is not supported on partitioned tables [#39915](https://github.com/pingcap/tidb/issues/39915) @[wjhuang2016](https://github.com/wjhuang2016) + - Disable renaming of columns that partition tables depend on [#40150](https://github.com/pingcap/tidb/issues/40150) @[mjonss](https://github.com/mjonss) + - Refine the error message reported when a column that a partitioned table depends on is deleted [#38739](https://github.com/pingcap/tidb/issues/38739) @[jiyfhust](https://github.com/jiyfhust) + - Add a mechanism that `FLASHBACK CLUSTER` retries when it fails to check the `min-resolved-ts` [#39836](https://github.com/pingcap/tidb/issues/39836) @[Defined2014](https://github.com/Defined2014) + ++ TiKV + + - Optimize the default values of some parameters in partitioned-raft-kv mode: the default value of the TiKV configuration item `storage.block-cache.capacity` is adjusted from 45% to 30%, and the default value of `region-split-size` is adjusted from `96MiB` adjusted to `10GiB`. When using raft-kv mode and `enable-region-bucket` is `true`, `region-split-size` is adjusted to 1 GiB by default. [#12842](https://github.com/tikv/tikv/issues/12842) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Support priority scheduling in Raftstore asynchronous writes [#13730](https://github.com/tikv/tikv/issues/13730) @[Connor1996](https://github.com/Connor1996) + - Support starting TiKV on a CPU with less than 1 core [#13586](https://github.com/tikv/tikv/issues/13586) [#13752](https://github.com/tikv/tikv/issues/13752) [#14017](https://github.com/tikv/tikv/issues/14017) @[andreid-db](https://github.com/andreid-db) + - Optimize the new detection mechanism of Raftstore slow score and add `evict-slow-trend-scheduler` [#14131](https://github.com/tikv/tikv/issues/14131) @[innerr](https://github.com/innerr) + - Force the block cache of RocksDB to be shared and no longer support setting the block cache separately according to CF [#12936](https://github.com/tikv/tikv/issues/12936) @[busyjay](https://github.com/busyjay) + ++ PD + + - Support managing the global memory threshold to alleviate the OOM problem (experimental) [#5827](https://github.com/tikv/pd/issues/5827) @[hnes](https://github.com/hnes) + - Add the GC Tuner to alleviate the GC pressure (experimental) [#5827](https://github.com/tikv/pd/issues/5827) @[hnes](https://github.com/hnes) + - Add the `evict-slow-trend-scheduler` scheduler to detect and schedule abnormal nodes [#5808](https://github.com/tikv/pd/pull/5808) @[innerr](https://github.com/innerr) + - Add the keyspace manager to manage keyspace [#5293](https://github.com/tikv/pd/issues/5293) @[AmoebaProtozoa](https://github.com/AmoebaProtozoa) + ++ TiFlash + + - Support an independent MVCC bitmap filter that decouples the MVCC filtering operations in the TiFlash data scanning process, which provides the foundation for future optimization of the data scanning process [#6296](https://github.com/pingcap/tiflash/issues/6296) @[JinheLin](https://github.com/JinheLin) + - Reduce the memory usage of TiFlash by up to 30% when there is no query [#6589](https://github.com/pingcap/tiflash/pull/6589) @[hongyunyan](https://github.com/hongyunyan) + ++ Tools + + + Backup & Restore (BR) + + - Optimize the concurrency of downloading log backup files on the TiKV side to improve the performance of PITR recovery in regular scenarios [#14206](https://github.com/tikv/tikv/issues/14206) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Support batch `UPDATE` DML statements to improve TiCDC replication performance [#8084](https://github.com/pingcap/tiflow/issues/8084) @[amyangfei](https://github.com/amyangfei) + - Implement MQ sink and MySQL sink in the asynchronous mode to improve the sink throughput [#5928](https://github.com/pingcap/tiflow/issues/5928) @[hicqu](https://github.com/hicqu) @[hi-rustin](https://github.com/Rustin170506) + + + TiDB Data Migration (DM) + + - Optimize DM alert rules and content [#7376](https://github.com/pingcap/tiflow/issues/7376) @[D3Hunter](https://github.com/D3Hunter) + + Previously, alerts similar to "DM_XXX_process_exits_with_error" were raised whenever a related error occurred. But some alerts are caused by idle database connections, which can be recovered after reconnecting. To reduce these kinds of alerts, DM divides errors into two types: automatically recoverable errors and unrecoverable errors: + + - For an error that is automatically recoverable, DM reports the alert only if the error occurs more than 3 times within 2 minutes. + - For an error that is not automatically recoverable, DM maintains the original behavior and reports the alert immediately. + + - Optimize relay performance by adding the async/batch relay writer [#4287](https://github.com/pingcap/tiflow/issues/4287) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Physical Import Mode supports keyspace [#40531](https://github.com/pingcap/tidb/issues/40531) @[iosmanthus](https://github.com/iosmanthus) + - Support setting the maximum number of conflicts by `lightning.max-error` [#40743](https://github.com/pingcap/tidb/issues/40743) @[dsdashun](https://github.com/dsdashun) + - Support importing CSV data files with BOM headers [#40744](https://github.com/pingcap/tidb/issues/40744) @[dsdashun](https://github.com/dsdashun) + - Optimize the processing logic when encountering TiKV flow-limiting errors and try other available regions instead [#40205](https://github.com/pingcap/tidb/issues/40205) @[lance6716](https://github.com/lance6716) + - Disable checking the table foreign keys during import [#40027](https://github.com/pingcap/tidb/issues/40027) @[sleepymole](https://github.com/sleepymole) + + + Dumpling + + - Support exporting settings for foreign keys [#39913](https://github.com/pingcap/tidb/issues/39913) @[lichunzhu](https://github.com/lichunzhu) + + + sync-diff-inspector + + - Add a new parameter `skip-non-existing-table` to control whether to skip checking upstream and downstream data consistency when tables in the downstream do not exist in the upstream [#692](https://github.com/pingcap/tidb-tools/issues/692) @[lichunzhu](https://github.com/lichunzhu) @[liumengya94](https://github.com/liumengya94) + +## Bug fixes + ++ TiDB + + - Fix the issue that a statistics collection task fails due to an incorrect `datetime` value [#39336](https://github.com/pingcap/tidb/issues/39336) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that `stats_meta` is not created following table creation [#38189](https://github.com/pingcap/tidb/issues/38189) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix frequent write conflicts in transactions when performing DDL data backfill [#24427](https://github.com/pingcap/tidb/issues/24427) @[mjonss](https://github.com/mjonss) + - Fix the issue that sometimes an index cannot be created for an empty table using ingest mode [#39641](https://github.com/pingcap/tidb/issues/39641) @[tangenta](https://github.com/tangenta) + - Fix the issue that `wait_ts` in the slow query log is the same for different SQL statements within the same transaction [#39713](https://github.com/pingcap/tidb/issues/39713) @[TonsnakeLin](https://github.com/TonsnakeLin) + - Fix the issue that the `Assertion Failed` error is reported when adding a column during the process of deleting a row record [#39570](https://github.com/pingcap/tidb/issues/39570) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the `not a DDL owner` error is reported when modifying a column type [#39643](https://github.com/pingcap/tidb/issues/39643) @[zimulala](https://github.com/zimulala) + - Fix the issue that no error is reported when inserting a row after exhaustion of the auto-increment values of the `AUTO_INCREMENT` column [#38950](https://github.com/pingcap/tidb/issues/38950) @[Dousir9](https://github.com/Dousir9) + - Fix the issue that the `Unknown column` error is reported when creating an expression index [#39784](https://github.com/pingcap/tidb/issues/39784) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that data cannot be inserted into a renamed table when the generated expression includes the name of this table [#39826](https://github.com/pingcap/tidb/issues/39826) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the `INSERT ignore` statement cannot fill in default values when the column is write-only [#40192](https://github.com/pingcap/tidb/issues/40192) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that resources are not released when disabling the resource management module [#40546](https://github.com/pingcap/tidb/issues/40546) @[zimulala](https://github.com/zimulala) + - Fix the issue that TTL tasks cannot trigger statistics updates in time [#40109](https://github.com/pingcap/tidb/issues/40109) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that unexpected data is read because TiDB improperly handles `NULL` values when constructing key ranges [#40158](https://github.com/pingcap/tidb/issues/40158) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that illegal values are written to a table when the `MODIFY COLUMN` statement also changes the default value of a column [#40164](https://github.com/pingcap/tidb/issues/40164) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the adding index operation is inefficient due to invalid Region cache when there are many Regions in a table [#38436](https://github.com/pingcap/tidb/issues/38436) @[tangenta](https://github.com/tangenta) + - Fix data race occurred in allocating auto-increment IDs [#40584](https://github.com/pingcap/tidb/issues/40584) @[Dousir9](https://github.com/Dousir9) + - Fix the issue that the implementation of the not operator in JSON is incompatible with the implementation in MySQL [#40683](https://github.com/pingcap/tidb/issues/40683) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that concurrent view might cause DDL operations to be blocked [#40352](https://github.com/pingcap/tidb/issues/40352) @[zeminzhou](https://github.com/zeminzhou) + - Fix data inconsistency caused by concurrently executing DDL statements to modify columns of partitioned tables [#40620](https://github.com/pingcap/tidb/issues/40620) @[mjonss](https://github.com/mjonss) @[mjonss](https://github.com/mjonss) + - Fix the issue that "Malformed packet" is reported when using `caching_sha2_password` for authentication without specifying a password [#40831](https://github.com/pingcap/tidb/issues/40831) @[dveeden](https://github.com/dveeden) + - Fix the issue that a TTL task fails if the primary key of the table contains an `ENUM` column [#40456](https://github.com/pingcap/tidb/issues/40456) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that some DDL operations blocked by MDL cannot be queried in `mysql.tidb_mdl_view` [#40838](https://github.com/pingcap/tidb/issues/40838) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that data race might occur during DDL ingestion [#40970](https://github.com/pingcap/tidb/issues/40970) @[tangenta](https://github.com/tangenta) + - Fix the issue that TTL tasks might delete some data incorrectly after the time zone changes [#41043](https://github.com/pingcap/tidb/issues/41043) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that `JSON_OBJECT` might report an error in some cases [#39806](https://github.com/pingcap/tidb/issues/39806) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that TiDB might deadlock during initialization [#40408](https://github.com/pingcap/tidb/issues/40408) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the value of system variables might be incorrectly modified in some cases due to memory reuse [#40979](https://github.com/pingcap/tidb/issues/40979) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that data might be inconsistent with the index when a unique index is created in the ingest mode [#40464](https://github.com/pingcap/tidb/issues/40464) @[tangenta](https://github.com/tangenta) + - Fix the issue that some truncate operations cannot be blocked by MDL when truncating the same table concurrently [#40484](https://github.com/pingcap/tidb/issues/40484) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the `SHOW PRIVILEGES` statement returns an incomplete privilege list [#40591](https://github.com/pingcap/tidb/issues/40591) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that TiDB panics when adding a unique index [#40592](https://github.com/pingcap/tidb/issues/40592) @[tangenta](https://github.com/tangenta) + - Fix the issue that executing the `ADMIN RECOVER` statement might cause the index data to be corrupted [#40430](https://github.com/pingcap/tidb/issues/40430) @[xiongjiwei](https://github.com/xiongjiwei) + - Fix the issue that a query might fail when the queried table contains a `CAST` expression in the expression index [#40130](https://github.com/pingcap/tidb/issues/40130) @[xiongjiwei](https://github.com/xiongjiwei) + - Fix the issue that a unique index might still produce duplicate data in some cases [#40217](https://github.com/pingcap/tidb/issues/40217) @[tangenta](https://github.com/tangenta) + - Fix the PD OOM issue when there is a large number of Regions but the table ID cannot be pushed down when querying some virtual tables using `Prepare` or `Execute` [#39605](https://github.com/pingcap/tidb/issues/39605) @[djshow832](https://github.com/djshow832) + - Fix the issue that data race might occur when an index is added [#40879](https://github.com/pingcap/tidb/issues/40879) @[tangenta](https://github.com/tangenta) + - Fix the `can't find proper physical plan` issue caused by virtual columns [#41014](https://github.com/pingcap/tidb/issues/41014) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that TiDB cannot restart after global bindings are created for partition tables in dynamic trimming mode [#40368](https://github.com/pingcap/tidb/issues/40368) @[Yisaer](https://github.com/Yisaer) + - Fix the issue that `auto analyze` causes graceful shutdown to take a long time [#40038](https://github.com/pingcap/tidb/issues/40038) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the panic of the TiDB server when the IndexMerge operator triggers memory limiting behaviors [#41036](https://github.com/pingcap/tidb/pull/41036) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the `SELECT * FROM table_name LIMIT 1` query on partitioned tables is slow [#40741](https://github.com/pingcap/tidb/pull/40741) @[solotzg](https://github.com/solotzg) + ++ TiKV + + - Fix an error that occurs when casting the `const Enum` type to other types [#14156](https://github.com/tikv/tikv/issues/14156) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that Resolved TS causes higher network traffic [#14092](https://github.com/tikv/tikv/issues/14092) @[overvenus](https://github.com/overvenus) + - Fix the data inconsistency issue caused by network failure between TiDB and TiKV during the execution of a DML after a failed pessimistic DML [#14038](https://github.com/tikv/tikv/issues/14038) @[MyonKeminta](https://github.com/MyonKeminta) + ++ PD + + - Fix the issue that the Region Scatter task generates redundant replicas unexpectedly [#5909](https://github.com/tikv/pd/issues/5909) @[HundunDM](https://github.com/HunDunDM) + - Fix the issue that the Online Unsafe Recovery feature would get stuck and time out in `auto-detect` mode [#5753](https://github.com/tikv/pd/issues/5753) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the execution `replace-down-peer` slows down under certain conditions [#5788](https://github.com/tikv/pd/issues/5788) @[HundunDM](https://github.com/HunDunDM) + - Fix the PD OOM issue that occurs when the calls of `ReportMinResolvedTS` are too frequent [#5965](https://github.com/tikv/pd/issues/5965) @[HundunDM](https://github.com/HunDunDM) + ++ TiFlash + + - Fix the issue that querying TiFlash-related system tables might get stuck [#6745](https://github.com/pingcap/tiflash/pull/6745) @[lidezhu](https://github.com/lidezhu) + - Fix the issue that semi-joins use excessive memory when calculating Cartesian products [#6730](https://github.com/pingcap/tiflash/issues/6730) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that the result of the division operation on the DECIMAL data type is not rounded [#6393](https://github.com/pingcap/tiflash/issues/6393) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that `start_ts` cannot uniquely identify an MPP query in TiFlash queries, which might cause an MPP query to be incorrectly canceled [#43426](https://github.com/pingcap/tidb/issues/43426) @[hehechen](https://github.com/hehechen) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that when restoring log backup, hot Regions cause the restore to fail [#37207](https://github.com/pingcap/tidb/issues/37207) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that restoring data to a cluster on which the log backup is running causes the log backup file to be unrecoverable [#40797](https://github.com/pingcap/tidb/issues/40797) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the PITR feature does not support CA-bundles [#38775](https://github.com/pingcap/tidb/issues/38775) @[YuJuncen](https://github.com/YuJuncen) + - Fix the panic issue caused by duplicate temporary tables during recovery [#40797](https://github.com/pingcap/tidb/issues/40797) @[joccau](https://github.com/joccau) + - Fix the issue that PITR does not support configuration changes for PD clusters [#14165](https://github.com/tikv/tikv/issues/14165) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the connection failure between PD and tidb-server causes PITR backup progress not to advance [#41082](https://github.com/pingcap/tidb/issues/41082) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV cannot listen to PITR tasks due to the connection failure between PD and TiKV [#14159](https://github.com/tikv/tikv/issues/14159) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the frequency of `resolve lock` is too high when there is no PITR backup task in the TiDB cluster [#40759](https://github.com/pingcap/tidb/issues/40759) @[joccau](https://github.com/joccau) + - Fix the issue that when a PITR backup task is deleted, the residual backup data causes data inconsistency in new tasks [#40403](https://github.com/pingcap/tidb/issues/40403) @[joccau](https://github.com/joccau) + + + TiCDC + + - Fix the issue that `transaction_atomicity` and `protocol` cannot be updated via the configuration file [#7935](https://github.com/pingcap/tiflow/issues/7935) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that precheck is not performed on the storage path of redo log [#6335](https://github.com/pingcap/tiflow/issues/6335) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue of insufficient duration that redo log can tolerate for S3 storage failure [#8089](https://github.com/pingcap/tiflow/issues/8089) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that changefeed might get stuck in special scenarios such as when scaling in or scaling out TiKV or TiCDC nodes [#8174](https://github.com/pingcap/tiflow/issues/8174) @[hicqu](https://github.com/hicqu) + - Fix the issue of too high traffic among TiKV nodes [#14092](https://github.com/tikv/tikv/issues/14092) @[overvenus](https://github.com/overvenus) + - Fix the performance issues of TiCDC in terms of CPU usage, memory control, and throughput when the pull-based sink is enabled [#8142](https://github.com/pingcap/tiflow/issues/8142) [#8157](https://github.com/pingcap/tiflow/issues/8157) [#8001](https://github.com/pingcap/tiflow/issues/8001) [#5928](https://github.com/pingcap/tiflow/issues/5928) @[hicqu](https://github.com/hicqu) @[hi-rustin](https://github.com/Rustin170506) + + + TiDB Data Migration (DM) + + - Fix the issue that the `binlog-schema delete` command fails to execute [#7373](https://github.com/pingcap/tiflow/issues/7373) @[liumengya94](https://github.com/liumengya94) + - Fix the issue that the checkpoint does not advance when the last binlog is a skipped DDL [#8175](https://github.com/pingcap/tiflow/issues/8175) @[D3Hunter](https://github.com/D3Hunter) + - Fix a bug that when the expression filters of both "update" and "non-update" types are specified in one table, all `UPDATE` statements are skipped [#7831](https://github.com/pingcap/tiflow/issues/7831) @[lance6716](https://github.com/lance6716) + - Fix a bug that when only one of `update-old-value-expr` or `update-new-value-expr` is set for a table, the filter rule does not take effect or DM panics [#7774](https://github.com/pingcap/tiflow/issues/7774) @[lance6716](https://github.com/lance6716) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning timeout hangs due to TiDB restart in some scenarios [#33714](https://github.com/pingcap/tidb/issues/33714) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that TiDB Lightning might incorrectly skip conflict resolution when all but the last TiDB Lightning instance encounters a local duplicate record during a parallel import [#40923](https://github.com/pingcap/tidb/issues/40923) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that precheck cannot accurately detect the presence of a running TiCDC in the target cluster [#41040](https://github.com/pingcap/tidb/issues/41040) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB Lightning panics in the split-region phase [#40934](https://github.com/pingcap/tidb/issues/40934) @[lance6716](https://github.com/lance6716) + - Fix the issue that the conflict resolution logic (`duplicate-resolution`) might lead to inconsistent checksums [#40657](https://github.com/pingcap/tidb/issues/40657) @[sleepymole](https://github.com/sleepymole) + - Fix a possible OOM problem when there is an unclosed delimiter in the data file [#40400](https://github.com/pingcap/tidb/issues/40400) @[buchuitoudegou](https://github.com/buchuitoudegou) + - Fix the issue that the file offset in the error report exceeds the file size [#40034](https://github.com/pingcap/tidb/issues/40034) @[buchuitoudegou](https://github.com/buchuitoudegou) + - Fix an issue with the new version of PDClient that might cause parallel import to fail [#40493](https://github.com/pingcap/tidb/issues/40493) @[AmoebaProtozoa](https://github.com/AmoebaProtozoa) + - Fix the issue that TiDB Lightning prechecks cannot find dirty data left by previously failed imports [#39477](https://github.com/pingcap/tidb/issues/39477) @[dsdashun](https://github.com/dsdashun) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [morgo](https://github.com/morgo) +- [jiyfhust](https://github.com/jiyfhust) +- [b41sh](https://github.com/b41sh) +- [sourcelliu](https://github.com/sourcelliu) +- [songzhibin97](https://github.com/songzhibin97) +- [mamil](https://github.com/mamil) +- [Dousir9](https://github.com/Dousir9) +- [hihihuhu](https://github.com/hihihuhu) +- [mychoxin](https://github.com/mychoxin) +- [xuning97](https://github.com/xuning97) +- [andreid-db](https://github.com/andreid-db) diff --git a/releases/release-7.0.0.md b/releases/release-7.0.0.md new file mode 100644 index 0000000000000..f52b8569cfd7a --- /dev/null +++ b/releases/release-7.0.0.md @@ -0,0 +1,512 @@ +--- +title: TiDB 7.0.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 7.0.0. +--- + +# TiDB 7.0.0 Release Notes + +Release date: March 30, 2023 + +TiDB version: 7.0.0-[DMR](/releases/versioning.md#development-milestone-releases) + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.0/quick-start-with-tidb) + +In v7.0.0-DMR, the key new features and improvements are as follows: + +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeatureDescription
Scalability and Performance
Session level non-prepared SQL plan cache (experimental)Support automatically reusing plan cache at the session level to reduce compilation and shorten the query time for the same SQL patterns without manually setting prepare statements in advance.
TiFlash supports the disaggregated storage and compute architecture and S3 shared storage (experimental)TiFlash introduces a cloud-native architecture as an option: +
    +
  • Disaggregates TiFlash's compute and storage, which is a milestone for elastic HTAP resource utilization.
    • +
  • Introduces S3-based storage engine, which can provide shared storage at a lower cost.
    • +
+
Reliability and Availability
Resource control enhancement (experimental) Support using resource groups to allocate and isolate resources for various applications or workloads within one cluster. In this release, TiDB adds support for different resource binding modes (user, session, and statement levels) and user-defined priorities. Additionally, you can also use commands to perform resource calibration (estimation for the whole resource amount).
TiFlash supports spill to diskTiFlash supports intermediate result spill to disk to mitigate OOMs in data-intensive operations such as aggregations, sorts, and hash joins.
SQLRow-level TTL (GA)Support managing database size and improve performance by automatically expiring data of a certain age.
Reorganize LIST/RANGE partitionThe REORGANIZE PARTITION statement can be used for merging adjacent partitions or splitting one partition into many, which provides better usability of partitioned tables.
DB Operations and Observability
TiDB enhances the functionalities of LOAD DATA statements (experimental)TiDB enhances the functionalities of LOAD DATA SQL statements, such as supporting data import from S3/GCS.
TiCDC supports object storage sink (GA)TiCDC supports replicating row change events to object storage services, including Amazon S3, GCS, Azure Blob Storage, and NFS.
+ +## Feature details + +### Scalability + +* TiFlash supports the disaggregated storage and compute architecture and supports object storage in this architecture (experimental) [#6882](https://github.com/pingcap/tiflash/issues/6882) @[flowbehappy](https://github.com/flowbehappy) + + Before v7.0.0, TiFlash only supports the coupled storage and compute architecture. In this architecture, each TiFlash node acts as both storage and compute node, and its computing and storage capabilities cannot be independently expanded. In addition, TiFlash nodes can only use local storage. + + Starting from v7.0.0, TiFlash also supports the disaggregated storage and compute architecture. In this architecture, TiFlash nodes are divided into two types (Compute Nodes and Write Nodes) and support object storage that is compatible with S3 API. Both types of nodes can be independently scaled for computing or storage capacities. The **disaggregated storage and compute architecture** and **coupled storage and compute architecture** cannot be used in the same cluster or converted to each other. You can configure which architecture to use when you deploy TiFlash. + + For more information, see [documentation](/tiflash/tiflash-disaggregated-and-s3.md). + +### Performance + +* Achieve compatibility between Fast Online DDL and PITR [#38045](https://github.com/pingcap/tidb/issues/38045) @[Leavrth](https://github.com/Leavrth) + + In TiDB v6.5.0, [Fast Online DDL](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630) is not fully compatible with [PITR](/br/backup-and-restore-overview.md). To ensure a full data backup, it is recommended to first stop the PITR background backup task, quickly add indexes using Fast Online DDL, and then resume the PITR backup task. + + Starting from TiDB v7.0.0, Fast Online DDL and PITR are fully compatible. When restoring cluster data through PITR, the index operations added via Fast Online DDL during log backup will be automatically replayed to achieve compatibility. + + For more information, see [documentation](/ddl-introduction.md). + +* TiFlash supports null-aware semi join and null-aware anti semi join operators [#6674](https://github.com/pingcap/tiflash/issues/6674) @[gengliqi](https://github.com/gengliqi) + + When using `IN`, `NOT IN`, `= ANY`, or `!= ALL` operators in correlated subqueries, TiDB optimizes the computing performance by converting them to semi join or anti semi join. If the join key column might be `NULL`, a null-aware join algorithm is required, such as [Null-aware semi join](/explain-subqueries.md#null-aware-semi-join-in-and--any-subqueries) and [Null-aware anti semi join](/explain-subqueries.md#null-aware-anti-semi-join-not-in-and--all-subqueries). + + Before v7.0.0, TiFlash does not support null-aware semi join and null-aware anti semi join operators, preventing these subqueries from being directly pushed down to TiFlash. Starting from v7.0.0, TiFlash supports null-aware semi join and null-aware anti semi join operators. If a SQL statement contains these correlated subqueries, the tables in the query have TiFlash replicas, and [MPP mode](/tiflash/use-tiflash-mpp-mode.md) is enabled, the optimizer automatically determines whether to push down null-aware semi join and null-aware anti semi join operators to TiFlash to improve overall performance. + + For more information, see [documentation](/tiflash/tiflash-supported-pushdown-calculations.md). + +* TiFlash supports using FastScan (GA) [#5252](https://github.com/pingcap/tiflash/issues/5252) @[hongyunyan](https://github.com/hongyunyan) + + Starting from v6.3.0, TiFlash introduces FastScan as an experimental feature. In v7.0.0, this feature becomes generally available. You can enable FastScan using the system variable [`tiflash_fastscan`](/system-variables.md#tiflash_fastscan-new-in-v630). By sacrificing strong consistency, this feature significantly improves table scan performance. If the corresponding table only involves `INSERT` operations without any `UPDATE`/`DELETE` operations, FastScan can keep strong consistency and improve the scan performance. + + For more information, see [documentation](/tiflash/use-fastscan.md). + +* TiFlash supports late materialization (experimental) [#5829](https://github.com/pingcap/tiflash/issues/5829) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + + When processing a `SELECT` statement with filter conditions (`WHERE` clause), TiFlash reads all the data from the columns required by the query by default, and then filters and aggregates the data based on the query conditions. Late materialization is an optimization method that supports pushing down part of the filter conditions to the TableScan operator. That is, TiFlash first scans the column data related to the filter conditions that are pushed down, filters the rows that meet the condition, and then scans the other column data of these rows for further calculation, thereby reducing IO scans and computations of data processing. + + The TiFlash late materialization feature is not enabled by default. You can enable it by setting the `tidb_opt_enable_late_materialization` system variable to `OFF`. When the feature is enabled, the TiDB optimizer will determine which filter conditions to be pushed down based on statistics and filter conditions. + + For more information, see [documentation](/tiflash/tiflash-late-materialization.md). + +* Support caching execution plans for non-prepared statements (experimental) [#36598](https://github.com/pingcap/tidb/issues/36598) @[qw4990](https://github.com/qw4990) + + The execution plan cache is important for improving the load capacity of concurrent OLTP and TiDB already supports [Prepared execution plan cache](/sql-prepared-plan-cache.md). In v7.0.0, TiDB can also cache execution plans for non-Prepare statements, expanding the scope of execution plan cache and improving the concurrent processing capacity of TiDB. + + This feature is disabled by default. You can enable it by setting the system variable [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache) to `ON`. For stability reasons, TiDB v7.0.0 allocates a new area for caching non-prepared execution plans and you can set the cache size using the system variable [`tidb_non_prepared_plan_cache_size`](/system-variables.md#tidb_non_prepared_plan_cache_size). Additionally, this feature has certain restrictions on SQL statements. For more information, see [Restrictions](/sql-non-prepared-plan-cache.md#restrictions). + + For more information, see [documentation](/sql-non-prepared-plan-cache.md). + +* TiDB removes the execution plan cache constraint for subqueries [#40219](https://github.com/pingcap/tidb/issues/40219) @[fzzf678](https://github.com/fzzf678) + + TiDB v7.0.0 removes the execution plan cache constraint for subqueries. This means that the execution plan of SQL statements with subqueries can now be cached, such as `SELECT * FROM t WHERE a > (SELECT ...)`. This feature further expands the application scope of execution plan cache and improves the execution efficiency of SQL queries. + + For more information, see [documentation](/sql-prepared-plan-cache.md). + +* TiKV supports automatically generating empty log files for log recycling [#14371](https://github.com/tikv/tikv/issues/14371) @[LykxSassinator](https://github.com/LykxSassinator) + + In v6.3.0, TiKV introduced the [Raft log recycling](/tikv-configuration-file.md#enable-log-recycle-new-in-v630) feature to reduce long-tail latency caused by write load. However, log recycling can only take effect when the number of Raft log files reaches a certain threshold, making it difficult for users to directly experience the throughput improvement brought by this feature. + + In v7.0.0, a new configuration item called `raft-engine.prefill-for-recycle` was introduced to improve user experience. This item controls whether empty log files are generated for recycling when the process starts. When this configuration is enabled, TiKV automatically fills a batch of empty log files during initialization, ensuring that log recycling takes effect immediately after initialization. + + For more information, see [documentation](/tikv-configuration-file.md#prefill-for-recycle-new-in-v700). + +* Support deriving the TopN or Limit operator from [window functions](/functions-and-operators/expressions-pushed-down.md) to improve window function performance [#13936](https://github.com/tikv/tikv/issues/13936) @[windtalker](https://github.com/windtalker) + + This feature is disabled by default. To enable it, you can set the session variable [tidb_opt_derive_topn](/system-variables.md#tidb_opt_derive_topn-new-in-v700) to `ON`. + + For more information, see [documentation](/derive-topn-from-window.md). + +* Support creating unique indexes through Fast Online DDL [#40730](https://github.com/pingcap/tidb/issues/40730) @[tangenta](https://github.com/tangenta) + + TiDB v6.5.0 supports creating ordinary secondary indexes via Fast Online DDL. TiDB v7.0.0 supports creating unique indexes via Fast Online DDL. Compared to v6.1.0, adding unique indexes to large tables is expected to be several times faster with improved performance. + + For more information, see [documentation](/ddl-introduction.md). + +### Reliability + +* Enhance the resource control feature (experimental) [#38825](https://github.com/pingcap/tidb/issues/38825) @[nolouch](https://github.com/nolouch) @[BornChanger](https://github.com/BornChanger) @[glorv](https://github.com/glorv) @[tiancaiamao](https://github.com/tiancaiamao) @[Connor1996](https://github.com/Connor1996) @[JmPotato](https://github.com/JmPotato) @[hnes](https://github.com/hnes) @[CabinfeverB](https://github.com/CabinfeverB) @[HuSharp](https://github.com/HuSharp) + + TiDB enhances the resource control feature based on resource groups. This feature significantly improves the resource utilization efficiency and performance of TiDB clusters. The introduction of the resource control feature is a milestone for TiDB. You can divide a distributed database cluster into multiple logical units, map different database users to corresponding resource groups, and set the quota for each resource group as needed. When the cluster resources are limited, all resources used by sessions in the same resource group are limited to the quota. In this way, even if a resource group is over-consumed, the sessions in other resource groups are not affected. + + With this feature, you can combine multiple small and medium-sized applications from different systems into a single TiDB cluster. When the workload of an application grows larger, it does not affect the normal operation of other applications. When the system workload is low, busy applications can still be allocated the required system resources even if they exceed the set quotas, so as to achieve the maximum utilization of resources. In addition, the rational use of the resource control feature can reduce the number of clusters, ease the difficulty of operation and maintenance, and save management costs. + + This feature provides a built-in Resource Control Dashboard for the actual usage of resources in Grafana, assisting you to allocate resources more rationally. It also supports dynamic resource management capabilities based on both session and statement levels (Hint). The introduction of this feature will help you gain more precise control over the resource usage of your TiDB cluster, and dynamically adjust quotas based on actual needs. + + In TiDB v7.0.0, you can set the absolute scheduling priority (`PRIORITY`) for resource groups to guarantee that important services can get resources. It also extends the way to set resource groups. + + You can use resource groups in the following ways: + + - User level. Bind a user using the [`CREATE USER`](/sql-statements/sql-statement-create-user.md) or [`ALTER USER`](/sql-statements/sql-statement-alter-user.md) statements to a specific resource group. After binding a resource group to a user, sessions newly created by the user are automatically bound to the corresponding resource group. + - Session level. Set the resource group used by the current session via [`SET RESOURCE GROUP`](/sql-statements/sql-statement-set-resource-group.md). + - Statement level. Set the resource group used by the current statement via [`RESOURCE_GROUP()`](/optimizer-hints.md#resource_groupresource_group_name). + + For more information, see [documentation](/tidb-resource-control.md). + +* Support a checkpoint mechanism for Fast Online DDL, improving fault tolerance and automatic recovery capability [#42164](https://github.com/pingcap/tidb/issues/42164) @[tangenta](https://github.com/tangenta) + + TiDB v7.0.0 introduces a checkpoint mechanism for [Fast Online DDL](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630), which significantly improves its fault tolerance and automatic recovery capabilities. By periodically recording and synchronizing the DDL progress, ongoing DDL operations can continue to be executed in Fast Online DDL mode even if there is a TiDB DDL Owner failure or switch. This makes the execution of DDL more stable and efficient. + + For more information, see [documentation](/ddl-introduction.md). + +* TiFlash supports spilling to disk [#6528](https://github.com/pingcap/tiflash/issues/6528) @[windtalker](https://github.com/windtalker) + + To improve execution performance, TiFlash runs data entirely in memory as much as possible. When the amount of data exceeds the total size of memory, TiFlash terminates the query to avoid system crashes caused by running out of memory. Therefore, the amount of data that TiFlash can handle is limited by the available memory. + + Starting from v7.0.0, TiFlash supports spilling to disk. By adjusting the threshold of memory usage for operators ([`tidb_max_bytes_before_tiflash_external_group_by`](/system-variables.md#tidb_max_bytes_before_tiflash_external_group_by-new-in-v700), [`tidb_max_bytes_before_tiflash_external_sort`](/system-variables.md#tidb_max_bytes_before_tiflash_external_sort-new-in-v700), and [`tidb_max_bytes_before_tiflash_external_join`](/system-variables.md#tidb_max_bytes_before_tiflash_external_join-new-in-v700)), you can control the maximum amount of memory that an operator can use. When the memory used by the operator exceeds the threshold, it automatically writes data to disk. This sacrifices some performance but allows for processing of more data. + + For more information, see [documentation](/tiflash/tiflash-spill-disk.md). + +* Improve the efficiency of collecting statistics [#41930](https://github.com/pingcap/tidb/issues/41930) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + In v7.0.0, TiDB further optimizes the logic of collecting statistics, reducing the collection time by about 25%. This optimization improves the operational efficiency and stability of large database clusters, reducing the impact of statistics collection on cluster performance. + +* Add new optimizer hints for MPP optimization [#39710](https://github.com/pingcap/tidb/issues/39710) @[Reminiscent](https://github.com/Reminiscent) + + In v7.0.0, TiDB adds a series of optimizer hints to influence the generation of MPP execution plans. + + - [`SHUFFLE_JOIN()`](/optimizer-hints.md#shuffle_joint1_name--tl_name-): takes effect on MPP. It hints the optimizer to use the Shuffle Join algorithm for the specified table. + - [`BROADCAST_JOIN()`](/optimizer-hints.md#broadcast_joint1_name--tl_name-): takes effect on MPP. It hints the optimizer to use the Broadcast Join algorithm for the specified table. + - [`MPP_1PHASE_AGG()`](/optimizer-hints.md#mpp_1phase_agg): takes effect on MPP. It hints the optimizer to use the one-phase aggregation algorithm for all aggregate functions in the specified query block. + - [`MPP_2PHASE_AGG()`](/optimizer-hints.md#mpp_2phase_agg): takes effect on MPP. It hints the optimizer to use the two-phase aggregation algorithm for all aggregate functions in the specified query block. + + MPP optimizer hints can help you intervene in HTAP queries, improving performance and stability for HTAP workloads. + + For more information, see [documentation](/optimizer-hints.md). + +* Optimizer hints support specifying join methods and join orders [#36600](https://github.com/pingcap/tidb/issues/36600) @[Reminiscent](https://github.com/Reminiscent) + + In v7.0.0, the optimizer hint [`LEADING()`](/optimizer-hints.md#leadingt1_name--tl_name-) can be used in conjunction with hints that affect the join method, and their behaviors are compatible. In the case of multi-table joins, you can effectively specify the optimal join method and join order, thereby enhancing the control of optimizer hints over execution plans. + + The new hint behavior has minor changes. To ensure forward compatibility, TiDB introduces the system variable [`tidb_opt_advanced_join_hint`](/system-variables.md#tidb_opt_advanced_join_hint-new-in-v700). When this variable is set to `OFF`, the optimizer hint behavior is compatible with earlier versions. When you upgrade your cluster from earlier versions to v7.0.0 or later versions, this variable will be set to `OFF`. To obtain more flexible hint behavior, after you confirm that the behavior does not cause a performance regression, it is strongly recommended to set this variable to `ON`. + + For more information, see [documentation](/optimizer-hints.md). + +### Availability + +* Support the `prefer-leader` option, which provides higher availability for read operations and reduces response latency in unstable network conditions [#40905](https://github.com/pingcap/tidb/issues/40905) @[LykxSassinator](https://github.com/LykxSassinator) + + You can control TiDB's data reading behavior through the system variable [`tidb_replica_read`](/system-variables.md#tidb_replica_read-new-in-v40). In v7.0.0, this variable adds the `prefer-leader` option. When the variable is set to `prefer-leader`, TiDB prioritizes selecting the leader replica to perform read operations. When the processing speed of the leader replica slows down significantly, such as due to disk or network performance fluctuations, TiDB selects other available follower replicas to perform read operations, providing higher availability and reducing response latency. + + For more information, see [documentation](/develop/dev-guide-use-follower-read.md). + +### SQL + +* Time to live (TTL) is generally available [#39262](https://github.com/pingcap/tidb/issues/39262) @[lcwangchao](https://github.com/lcwangchao) @[YangKeao](https://github.com/YangKeao) + + TTL provides row-level lifecycle control policies. In TiDB, tables with TTL attributes set automatically check and delete expired row data based on the configuration. The goal of TTL is to help users periodically clean up unnecessary data in time while minimizing the impact on cluster workloads. + + For more information, see [documentation](/time-to-live.md). + +* Support `ALTER TABLE…REORGANIZE PARTITION` [#15000](https://github.com/pingcap/tidb/issues/15000) @[mjonss](https://github.com/mjonss) + + TiDB supports the `ALTER TABLE...REORGANIZE PARTITION` syntax. Using this syntax, you can reorganize some or all of the partitions of a table, including merging, splitting, or other modifications, without losing data. + + For more information, see [documentation](/partitioned-table.md#reorganize-partitions). + +* Support Key partitioning [#41364](https://github.com/pingcap/tidb/issues/41364) @[TonsnakeLin](https://github.com/TonsnakeLin) + + Now TiDB supports Key partitioning. Both Key partitioning and Hash partitioning can evenly distribute data into a certain number of partitions. The difference is that Hash partitioning only supports distributing data based on a specified integer expression or an integer column, while Key partitioning supports distributing data based on a column list, and partitioning columns of Key partitioning are not limited to the integer type. + + For more information, see [documentation](/partitioned-table.md#key-partitioning). + +### DB operations + +* TiCDC supports replicating change data to storage services (GA) [#6797](https://github.com/pingcap/tiflow/issues/6797) @[zhaoxinyu](https://github.com/zhaoxinyu) + + TiCDC supports replicating changed data to Amazon S3, GCS, Azure Blob Storage, NFS, and other S3-compatible storage services. Storage services are reasonably priced and easy to use. If you are not using Kafka, you can use storage services. TiCDC saves the changed logs to a file and then sends it to the storage services instead. From the storage services, your own consumer program can read the newly generated changed log files periodically. Currently, TiCDC supports replicating changed logs in canal-json and CSV formats to the storage service. + + For more information, see [documentation](/ticdc/ticdc-sink-to-cloud-storage.md). + +* TiCDC OpenAPI v2 [#8019](https://github.com/pingcap/tiflow/issues/8019) @[sdojjy](https://github.com/sdojjy) + + TiCDC provides OpenAPI v2. Compared with OpenAPI v1, OpenAPI v2 provides more comprehensive support for replication tasks. The features provided by TiCDC OpenAPI are a subset of the [`cdc cli` tool](/ticdc/ticdc-manage-changefeed.md). You can query and operate TiCDC clusters via OpenAPI v2, such as getting TiCDC node status, checking cluster health status, and managing replication tasks. + + For more information, see [documentation](/ticdc/ticdc-open-api-v2.md). + +* [DBeaver](https://dbeaver.io/) v23.0.1 supports TiDB by default [#17396](https://github.com/dbeaver/dbeaver/issues/17396) @[Icemap](https://github.com/Icemap) + + - Provides an independent TiDB module, icon, and logo. + - The default configuration supports [TiDB Serverless](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-serverless), making it easier to connect to TiDB Serverless. + - Supports identifying TiDB versions to display or hide foreign key tabs. + - Supports visualizing SQL execution plans in `EXPLAIN` results. + - Supports highlighting TiDB keywords such as `PESSIMISTIC`, `OPTIMISTIC`, `AUTO_RANDOM`, `PLACEMENT`, `POLICY`, `REORGANIZE`, `EXCHANGE`, `CACHE`, `NONCLUSTERED`, and `CLUSTERED`. + - Supports highlighting TiDB functions such as  `TIDB_BOUNDED_STALENESS`, `TIDB_DECODE_KEY`, `TIDB_DECODE_PLAN`, `TIDB_IS_DDL_OWNER`, `TIDB_PARSE_TSO`, `TIDB_VERSION`, `TIDB_DECODE_SQL_DIGESTS`, and `TIDB_SHARD`. + + For more information, see [DBeaver documentation](https://github.com/dbeaver/dbeaver/wiki). + +### Data migration + +* Enhance the functionalities of `LOAD DATA` statements and support importing data from cloud storage (experimental) [#40499](https://github.com/pingcap/tidb/issues/40499) @[lance6716](https://github.com/lance6716) + + Before TiDB v7.0.0, the `LOAD DATA` statement could only import data files from the client side. If you wanted to import data from cloud storage, you had to rely on TiDB Lightning. However, deploying TiDB Lightning separately would bring additional deployment and management costs. In v7.0.0, you can directly import data from cloud storage using the `LOAD DATA` statement. Some examples of the feature are as follows: + + - Supports importing data from Amazon S3 and Google Cloud Storage to TiDB. Supports importing multiple source files to TiDB in one go with wildcards. + - Support using `DEFINED NULL BY` to define null. + - Support source files in CSV and TSV formats. + + For more information, see [documentation](/sql-statements/sql-statement-load-data.md). + +* TiDB Lightning supports enabling compressed transfers when sending key-value pairs to TiKV (GA) [#41163](https://github.com/pingcap/tidb/issues/41163) @[sleepymole](https://github.com/sleepymole) + + Starting from v6.6.0, TiDB Lightning supports compressing locally encoded and sorted key-value pairs for network transfer when sending them to TiKV, thus reducing the amount of data transferred over the network and lowering the network bandwidth overhead. In the earlier TiDB versions before this feature is supported, TiDB Lightning requires relatively high network bandwidth and incurs high traffic charges in case of large data volumes. + + In v7.0.0, this feature becomes GA and is disabled by default. To enable it, you can set the `compress-kv-pairs` configuration item of TiDB Lightning to `"gzip"` or `"gz"`. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v6.6.0 to the current version (v7.0.0). If you are upgrading from v6.5.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### MySQL compatibility + +* TiDB removes the constraint that the auto-increment column must be an index [#40580](https://github.com/pingcap/tidb/issues/40580) @[tiancaiamao](https://github.com/tiancaiamao) + + Before v7.0.0, TiDB's behavior is consistent with MySQL, requiring the auto-increment column to be an index or index prefix. Starting from v7.0.0, TiDB removes the constraint that the auto-increment column must be an index or index prefix. Now you can define the primary key of a table more flexibly and use the auto-increment column to implement sorting and pagination more conveniently. This also avoids the write hotspot problem caused by the auto-increment column and improves query performance by using the table with clustered indexes. With the new release, you can create a table using the following syntax: + + ```sql + CREATE TABLE test1 ( + `id` int(11) NOT NULL AUTO_INCREMENT, + `k` int(11) NOT NULL DEFAULT '0', + `c` char(120) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '', + PRIMARY KEY(`k`, `id`) + ); + ``` + + This feature does not affect TiCDC data replication. + + For more information, see [documentation](/mysql-compatibility.md#auto-increment-id). + +* TiDB supports Key partitions, as shown in the following example: + + ```sql + CREATE TABLE employees ( + id INT NOT NULL, + fname VARCHAR(30), + lname VARCHAR(30), + hired DATE NOT NULL DEFAULT '1970-01-01', + separated DATE DEFAULT '9999-12-31', + job_code INT, + store_id INT) PARTITION BY KEY(store_id) PARTITIONS 4; + ``` + + Starting from v7.0.0, TiDB supports Key partitions and can parse the MySQL `PARTITION BY LINEAR KEY` syntax. However, TiDB ignores the `LINEAR` keyword and uses a non-linear hash algorithm instead. Currently, the `KEY` partition type does not support partition statements with an empty partition column list. + + For more information, see [documentation](/partitioned-table.md#key-partitioning). + +### Behavior changes + +* TiCDC fixes the issue of incorrect encoding of `FLOAT` data in Avro [#8490](https://github.com/pingcap/tiflow/issues/8490) @[3AceShowHand](https://github.com/3AceShowHand) + + When upgrading the TiCDC cluster to v7.0.0, if a table replicated using Avro contains the `FLOAT` data type, you need to manually adjust the compatibility policy of Confluent Schema Registry to `None` before upgrading so that the changefeed can successfully update the schema. Otherwise, after upgrading, the changefeed will be unable to update the schema and enter an error state. + +* Starting from v7.0.0, [`tidb_dml_batch_size`](/system-variables.md#tidb_dml_batch_size) system variable no longer takes effect on the [`LOAD DATA` statement](/sql-statements/sql-statement-load-data.md). + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| `tidb_pessimistic_txn_aggressive_locking` | Deleted | This variable is renamed to [`tidb_pessimistic_txn_fair_locking`](/system-variables.md#tidb_pessimistic_txn_fair_locking-new-in-v700). | +| [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache) | Modified | Takes effect starting from v7.0.0 and controls whether to enable the [Non-prepared plan cache](/sql-non-prepared-plan-cache.md) feature. | +| [`tidb_enable_null_aware_anti_join`](/system-variables.md#tidb_enable_null_aware_anti_join-new-in-v630) | Modified | Changes the default value from `OFF` to `ON` after further tests, meaning that TiDB applies Null-Aware Hash Join when Anti Join is generated by subqueries led by special set operators `NOT IN` and `!= ALL` by default. | +| [`tidb_enable_resource_control`](/system-variables.md#tidb_enable_resource_control-new-in-v660) | Modified | Changes the default value from `OFF` to `ON`, meaning that the cluster isolates resources by resource group by default. Resource Control is enabled by default in v7.0.0, so that you can use this feature whenever you want. | +| [`tidb_non_prepared_plan_cache_size`](/system-variables.md#tidb_non_prepared_plan_cache_size) | Modified | Takes effect starting from v7.0.0 and controls the maximum number of execution plans that can be cached by [Non-prepared plan cache](/sql-non-prepared-plan-cache.md). | +| [`tidb_rc_read_check_ts`](/system-variables.md#tidb_rc_read_check_ts-new-in-v600) | Modified | Starting from v7.0.0, this variable is no longer effective for cursor fetch read in the prepared statement protocol. | +| [`tidb_enable_inl_join_inner_multi_pattern`](/system-variables.md#tidb_enable_inl_join_inner_multi_pattern-new-in-v700) | Newly added | This variable controls whether Index Join is supported when the inner table has `Selection` or `Projection` operators on it. | +| [`tidb_enable_plan_cache_for_subquery`](/system-variables.md#tidb_enable_plan_cache_for_subquery-new-in-v700) | Newly added | This variable controls whether Prepared Plan Cache caches queries that contain subqueries. | +| [`tidb_enable_plan_replayer_continuous_capture`](/system-variables.md#tidb_enable_plan_replayer_continuous_capture-new-in-v700) | Newly added | This variable controls whether to enable the [`PLAN REPLAYER CONTINUOUS CAPTURE`](/sql-plan-replayer.md#use-plan-replayer-continuous-capture) feature. The default value `OFF` means to disable the feature. | +| [`tidb_load_based_replica_read_threshold`](/system-variables.md#tidb_load_based_replica_read_threshold-new-in-v700) | Newly added | This variable sets the threshold for triggering load-based replica read. The feature controlled by this variable is not fully functional in TiDB v7.0.0. Do not change the default value. | +| [`tidb_opt_advanced_join_hint`](/system-variables.md#tidb_opt_advanced_join_hint-new-in-v700) | Newly added | This variable controls whether the join method hint influences the optimization of join reorder. The default value is `ON`, which means the new compatible control mode is used. The value `OFF` means the behavior before v7.0.0 is used. For forward compatibility, the value of this variable is set to `OFF` when the cluster is upgraded from an earlier version to v7.0.0 or later. | +| [`tidb_opt_derive_topn`](/system-variables.md#tidb_opt_derive_topn-new-in-v700) | Newly added | This variable controls whether to enable the [Derive TopN or Limit from Window Functions](/derive-topn-from-window.md) optimization rule. The default value is `OFF`, which means the optimization rule is not enabled. | +| [`tidb_opt_enable_late_materialization`](/system-variables.md#tidb_opt_enable_late_materialization-new-in-v700) | Newly added | This variable controls whether to enable the [TiFlash Late Materialization](/tiflash/tiflash-late-materialization.md) feature. The default value is `OFF`, which means the feature is not enabled. | +| [`tidb_opt_ordering_index_selectivity_threshold`](/system-variables.md#tidb_opt_ordering_index_selectivity_threshold-new-in-v700) | Newly added | This variable controls how the optimizer selects indexes when the SQL statement contains `ORDER BY` and `LIMIT` clauses and has filtering conditions. | +| [`tidb_pessimistic_txn_fair_locking`](/system-variables.md#tidb_pessimistic_txn_fair_locking-new-in-v700) | Newly added | Controls whether to enable the enhanced pessimistic lock-waking model to reduce the tail latency of transactions under single-row conflict scenarios. The default value is `ON`. When the cluster is upgraded from an earlier version to v7.0.0 or later, the value of this variable is set to `OFF`. | +| [`tidb_ttl_running_tasks`](/system-variables.md#tidb_ttl_running_tasks-new-in-v700) | Newly added | This variable is used to limit the concurrency of TTL tasks across the entire cluster. The default value `-1` means that the TTL tasks are the same as the number of TiKV nodes. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiKV | `server.snap-max-write-bytes-per-sec` | Deleted | This parameter is renamed to [`server.snap-io-max-bytes-per-sec`](/tikv-configuration-file.md#snap-io-max-bytes-per-sec). | +| TiKV | [`raft-engine.enable-log-recycle`](/tikv-configuration-file.md#enable-log-recycle-new-in-v630) | Modified | The default value changes from `false` to `true`. | +| TiKV | [`resolved-ts.advance-ts-interval`](/tikv-configuration-file.md#advance-ts-interval) | Modified | The default value changes from `"1s"` to `"20s"`. This modification can increase the interval of the regular advancement of Resolved TS and reduce the traffic consumption between TiKV nodes. | +| TiKV | [`resource-control.enabled`](/tikv-configuration-file.md#resource-control) | Modified | The default value changes from `false` to `true`. | +| TiKV | [`raft-engine.prefill-for-recycle`](/tikv-configuration-file.md#prefill-for-recycle-new-in-v700) | Newly added | Controls whether to generate empty log files for log recycling in Raft Engine. The default value is `false`. | +| PD | [`degraded-mode-wait-duration`](/pd-configuration-file.md#degraded-mode-wait-duration) | Newly added | A [Resource Control](/tidb-resource-control.md)-related configuration item. It controls the waiting time for triggering the degraded mode. The default value is `0s`. | +| PD | [`read-base-cost`](/pd-configuration-file.md#read-base-cost) | Newly added | A [Resource Control](/tidb-resource-control.md)-related configuration item. It controls the basis factor for conversion from a read request to RU. The default value is `0.25`. | +| PD | [`read-cost-per-byte`](/pd-configuration-file.md#read-cost-per-byte) | Newly added | A [Resource Control](/tidb-resource-control.md)-related configuration item. It controls the basis factor for conversion from read flow to RU. The default value is `1/ (64 * 1024)`. | +| PD | [`read-cpu-ms-cost`](/pd-configuration-file.md#read-cpu-ms-cost) | Newly added | A [Resource Control](/tidb-resource-control.md)-related configuration item. It controls the basis factor for conversion from CPU to RU. The default value is `1/3`. | +| PD | [`write-base-cost`](/pd-configuration-file.md#write-base-cost) | Newly added | A [Resource Control](/tidb-resource-control.md)-related configuration item. It controls the basis factor for conversion from a write request to RU. The default value is `1`. | +| PD | [`write-cost-per-byte`](/pd-configuration-file.md#write-cost-per-byte) | Newly added | A [Resource Control](/tidb-resource-control.md)-related configuration item. It controls the basis factor for conversion from write flow to RU. The default value is `1/1024`. | +| TiFlash | [`mark_cache_size`](/tiflash/tiflash-configuration.md) | Modified | Change the default cache limit of the metadata for a data block in TiFlash from `5368709120` to `1073741824` to reduce unnecessary memory usage. | +| TiFlash | [`minmax_index_cache_size`](/tiflash/tiflash-configuration.md) | Modified | Change the default cache limit of the min-max index for a data block in TiFlash from `5368709120` to `1073741824` to reduce unnecessary memory usage. | +| TiFlash | [`flash.disaggregated_mode`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | In the disaggregated architecture of TiFlash, it indicates whether this TiFlash node is a write node or a compute node. The value can be `tiflash_write` or `tiflash_compute`. | +| TiFlash | [`storage.s3.endpoint`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | The endpoint to connect to S3. | +| TiFlash | [`storage.s3.bucket`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | The bucket where TiFlash stores all data. | +| TiFlash | [`storage.s3.root`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | The root directory of data storage in S3 bucket. | +| TiFlash | [`storage.s3.access_key_id`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | `ACCESS_KEY_ID` for accessing S3. | +| TiFlash | [`storage.s3.secret_access_key`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | `SECRET_ACCESS_KEY` for accessing S3. | +| TiFlash | [`storage.remote.cache.dir`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | The local data cache directory of TiFlash compute node. | +| TiFlash | [`storage.remote.cache.capacity`](/tiflash/tiflash-disaggregated-and-s3.md) | Newly added | The size of the local data cache directory of TiFlash compute node. | +| TiDB Lightning | [`add-index-by-sql`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Newly added | Controls whether to use SQL to add indexes in physical import mode. The default value is `false`, which means that TiDB Lightning will encode both row data and index data into KV pairs and import them into TiKV together. The advantage of adding indexes using SQL is to separate the import of data and the import of indexes, which can quickly import data. Even if the index creation fails after the data is imported, the data consistency is not affected. | +| TiCDC | [`enable-table-across-nodes`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | Determines whether to divide a table into multiple sync ranges according to the number of Regions. These ranges can be replicated by multiple TiCDC nodes. | +| TiCDC | [`region-threshold`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | When `enable-table-across-nodes` is enabled, this feature only takes effect on tables with more than `region-threshold` Regions. | +| DM | [`analyze`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Controls whether to execute the `ANALYZE TABLE ` operation on each table after CHECKSUM is completed. It can be configured as `"required"`/`"optional"`/`"off"`. The default value is `"optional"`. | +| DM | [`range-concurrency`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Controls the concurrency of dm-worker writing KV data to TiKV. | +| DM | [`compress-kv-pairs`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Controls whether to enable compression when dm-worker sends KV data to TiKV. Currently, only gzip is supported. The default value is empty, which means no compression. | +| DM | [`pd-addr`](/dm/task-configuration-file-full.md#task-configuration-file-template-advanced) | Newly added | Controls the address of the downstream PD server in the Physical Import mode. You can fill in either one or more PD servers. If this configuration item is empty, use the PD address information from the TiDB query by default. | + +## Improvements + ++ TiDB + + - Introduce the `EXPAND` operator to optimize the performance of SQL queries with multiple `DISTINCT` in a single `SELECT` statement [#16581](https://github.com/pingcap/tidb/issues/16581) @[AilinKid](https://github.com/AilinKid) + - Support more SQL formats for Index Join [#40505](https://github.com/pingcap/tidb/issues/40505) @[Yisaer](https://github.com/Yisaer) + - Avoid globally sorting partitioned table data in TiDB in some cases [#26166](https://github.com/pingcap/tidb/issues/26166) @[Defined2014](https://github.com/Defined2014) + - Support using `fair lock mode` and `lock only if exists` at the same time [#42068](https://github.com/pingcap/tidb/issues/42068) @[MyonKeminta](https://github.com/MyonKeminta) + - Support printing transaction slow logs and transaction internal events [#41863](https://github.com/pingcap/tidb/issues/41863) @[ekexium](https://github.com/ekexium) + - Support the `ILIKE` operator [#40943](https://github.com/pingcap/tidb/issues/40943) @[xzhangxian1008](https://github.com/xzhangxian1008) + ++ PD + + - Add a new monitoring metric for scheduling failures due to the store limit [#6043](https://github.com/tikv/pd/issues/6043) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Reduce TiFlash's memory usage on write path [#7144](https://github.com/pingcap/tiflash/issues/7144) @[hongyunyan](https://github.com/hongyunyan) + - Reduce TiFlash's restart time in scenarios with many tables [#7146](https://github.com/pingcap/tiflash/issues/7146) @[hongyunyan](https://github.com/hongyunyan) + - Support pushing down the `ILIKE` operator [#6740](https://github.com/pingcap/tiflash/issues/6740) @[xzhangxian1008](https://github.com/xzhangxian1008) + ++ Tools + + + TiCDC + + - Support distributing data changes of a single large table to multiple TiCDC nodes in scenarios where Kafka is the downstream, thus solving the scalability issue of single tables in data integration scenarios of large-scale TiDB clusters [#8247](https://github.com/pingcap/tiflow/issues/8247) @[overvenus](https://github.com/overvenus) + + You can enable this feature by setting the TiCDC configuration item `enable_table_across_nodes` to `true`. You can use `region_threshold` to specify that when the number of Regions for a table exceeds this threshold, TiCDC starts distributing data changes of the corresponding table to multiple TiCDC nodes. + + - Support splitting transactions in the redo applier to improve its throughput and reduce RTO in disaster recovery scenarios [#8318](https://github.com/pingcap/tiflow/issues/8318) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Improve the table scheduling to split a single table more evenly across various TiCDC nodes [#8247](https://github.com/pingcap/tiflow/issues/8247) @[overvenus](https://github.com/overvenus) + - Add the Large Row monitoring metrics in MQ sink [#8286](https://github.com/pingcap/tiflow/issues/8286) @[hi-rustin](https://github.com/Rustin170506) + - Reduce network traffic between TiKV and TiCDC nodes in scenarios where a Region contains data of multiple tables [#6346](https://github.com/pingcap/tiflow/issues/6346) @[overvenus](https://github.com/overvenus) + - Move the P99 metrics panel of Checkpoint TS and Resolved TS to the Lag analyze panel [#8524](https://github.com/pingcap/tiflow/issues/8524) @[hi-rustin](https://github.com/Rustin170506) + - Support applying DDL events in redo logs [#8361](https://github.com/pingcap/tiflow/issues/8361) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support splitting and scheduling tables to TiCDC nodes based on upstream write throughput [#7720](https://github.com/pingcap/tiflow/issues/7720) @[overvenus](https://github.com/overvenus) + + + TiDB Lightning + + - TiDB Lightning Physical Import Mode supports separating data import and index import to improve import speed and stability [#42132](https://github.com/pingcap/tidb/issues/42132) @[sleepymole](https://github.com/sleepymole) + + Add the `add-index-by-sql` parameter. The default value is `false`, which means that TiDB Lightning encodes both row data and index data into KV pairs and import them into TiKV together. If you set it to `true`, it means that TiDB Lightning adds indexes via the `ADD INDEX` SQL statement after importing the row data to improve import speed and stability. + + - Add the `tikv-importer.keyspace-name` parameter. The default value is an empty string, which means TiDB Lightning automatically gets the key space name of the corresponding tenant to import data. If you specify a value, the specified key space name will be used to import data. This parameter provides flexibility in the configuration of TiDB Lightning when you import data to a multi-tenant TiDB cluster. [#41915](https://github.com/pingcap/tidb/issues/41915) @[lichunzhu](https://github.com/lichunzhu) + +## Bug fixes + ++ TiDB + + - Fix the issue of missing updates when upgrading TiDB from v6.5.1 to a later version [#41502](https://github.com/pingcap/tidb/issues/41502) @[chrysan](https://github.com/chrysan) + - Fix the issue that the default values of some system variables are not modified after upgrading [#41423](https://github.com/pingcap/tidb/issues/41423) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that Coprocessor request types related to adding indexes are displayed as unknown [#41400](https://github.com/pingcap/tidb/issues/41400) @[tangenta](https://github.com/tangenta) + - Fix the issue of returning "PessimisticLockNotFound" when adding an index [#41515](https://github.com/pingcap/tidb/issues/41515) @[tangenta](https://github.com/tangenta) + - Fix the issue of mistakenly returning `found duplicate key` when adding a unique index [#41630](https://github.com/pingcap/tidb/issues/41630) @[tangenta](https://github.com/tangenta) + - Fix the panic issue when adding an index [#41880](https://github.com/pingcap/tidb/issues/41880) @[tangenta](https://github.com/tangenta) + - Fix the issue that TiFlash reports an error for generated columns during execution [#40663](https://github.com/pingcap/tidb/issues/40663) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiDB might not be able to obtain statistics correctly when there is a time type [#41938](https://github.com/pingcap/tidb/issues/41938) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that full index scans might cause errors when prepared plan cache is enabled [#42150](https://github.com/pingcap/tidb/issues/42150) @[fzzf678](https://github.com/fzzf678) + - Fix the issue that `IFNULL(NOT NULL COLUMN, ...)` might return incorrect results [#41734](https://github.com/pingcap/tidb/issues/41734) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that TiDB might produce incorrect results when all data in a partitioned table is in a single Region [#41801](https://github.com/pingcap/tidb/issues/41801) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that TiDB might produce incorrect results when different partitioned tables appear in a single SQL statement [#42135](https://github.com/pingcap/tidb/issues/42135) @[mjonss](https://github.com/mjonss) + - Fix the issue that statistics auto-collection might not trigger correctly on a partitioned table after adding a new index to the partitioned table [#41638](https://github.com/pingcap/tidb/issues/41638) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that TiDB might read incorrect column statistics information after collecting statistics twice in a row [#42073](https://github.com/pingcap/tidb/issues/42073) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the issue that IndexMerge might produce incorrect results when prepare plan cache is enabled [#41828](https://github.com/pingcap/tidb/issues/41828) @[qw4990](https://github.com/qw4990) + - Fix the issue that IndexMerge might have goroutine leakage [#41605](https://github.com/pingcap/tidb/issues/41605) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that non-BIGINT unsigned integers might produce incorrect results when compared with strings/decimals [#41736](https://github.com/pingcap/tidb/issues/41736) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that killing a previous `ANALYZE` statement due to memory over-limit might cause the current `ANALYZE` statement in the same session to be killed [#41825](https://github.com/pingcap/tidb/issues/41825) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that data race might occur during the information collection process of the batch coprocessor [#41412](https://github.com/pingcap/tidb/issues/41412) @[you06](https://github.com/you06) + - Fix the issue that an assertion error prevents printing MVCC information for partitioned tables [#40629](https://github.com/pingcap/tidb/issues/40629) @[ekexium](https://github.com/ekexium) + - Fix the issue that fair lock mode adds locking to non-existent keys [#41527](https://github.com/pingcap/tidb/issues/41527) @[ekexium](https://github.com/ekexium) + - Fix the issue that `INSERT IGNORE` and `REPLACE` statements do not lock keys that do not modify values [#42121](https://github.com/pingcap/tidb/issues/42121) @[zyguan](https://github.com/zyguan) + ++ PD + + - Fix the issue that the Region Scatter operation might cause uneven distribution of leaders [#6017](https://github.com/tikv/pd/issues/6017) @[HunDunDM](https://github.com/HunDunDM) + - Fix the issue that data race might occur when getting PD members during startup [#6069](https://github.com/tikv/pd/issues/6069) @[rleungx](https://github.com/rleungx) + - Fix the issue that data race might occur when collecting hotspot statistics [#6069](https://github.com/tikv/pd/issues/6069) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that switching placement rule might cause uneven distribution of leaders [#6195](https://github.com/tikv/pd/issues/6195) @[bufferflies](https://github.com/bufferflies) + ++ TiFlash + + - Fix the issue that Decimal division does not round up the last digit in certain cases [#7022](https://github.com/pingcap/tiflash/issues/7022) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that Decimal cast rounds up incorrectly in certain cases [#6994](https://github.com/pingcap/tiflash/issues/6994) @[windtalker](https://github.com/windtalker) + - Fix the issue that TopN/Sort operators produce incorrect results after enabling the new collation [#6807](https://github.com/pingcap/tiflash/issues/6807) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that TiFlash reports an error when aggregating a result set larger than 12 million rows on a single TiFlash node [#6993](https://github.com/pingcap/tiflash/issues/6993) @[windtalker](https://github.com/windtalker) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue of insufficient wait time for splitting Region retry during the PITR recovery process [#42001](https://github.com/pingcap/tidb/issues/42001) @[joccau](https://github.com/joccau) + - Fix the issue of recovery failures due to `memory is limited` error encountered during the PITR recovery process [#41983](https://github.com/pingcap/tidb/issues/41983) @[joccau](https://github.com/joccau) + - Fix the issue that PITR log backup progress does not advance when a PD node is down [#14184](https://github.com/tikv/tikv/issues/14184) @[YuJuncen](https://github.com/YuJuncen) + - Alleviate the issue that the latency of the PITR log backup progress increases when Region leadership migration occurs [#13638](https://github.com/tikv/tikv/issues/13638) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the issue that restarting the changefeed might cause data loss or that the checkpoint cannot advance [#8242](https://github.com/pingcap/tiflow/issues/8242) @[overvenus](https://github.com/overvenus) + - Fix the data race issue in DDL sink [#8238](https://github.com/pingcap/tiflow/issues/8238) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the changefeed in the `stopped` status might restart automatically [#8330](https://github.com/pingcap/tiflow/issues/8330) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that the TiCDC server panics when all downstream Kafka servers are unavailable [#8523](https://github.com/pingcap/tiflow/issues/8523) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that data might be lost when the downstream is MySQL and the executed statement is incompatible with TiDB [#8453](https://github.com/pingcap/tiflow/issues/8453) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that rolling upgrade might cause TiCDC OOM or that the checkpoint gets stuck [#8329](https://github.com/pingcap/tiflow/issues/8329) @[overvenus](https://github.com/overvenus) + - Fix the issue that graceful upgrade for TiCDC clusters fails on Kubernetes [#8484](https://github.com/pingcap/tiflow/issues/8484) @[overvenus](https://github.com/overvenus) + + + TiDB Data Migration (DM) + + - Fix the issue that when a DM worker node uses Google Cloud Storage, due to too frequent breakpoints, the request frequency limit of Google Cloud Storage is reached and the DM worker cannot write the data into Google Cloud Storage, thus causing the full data to fail to load [#8482](https://github.com/pingcap/tiflow/issues/8482) @[maxshuang](https://github.com/maxshuang) + - Fix the issue that when multiple DM tasks replicate the same downstream data at the same time and all use the downstream metadata table to record the breakpoint information, the breakpoint information of all tasks is written to the same metadata table and uses the same task ID [#8500](https://github.com/pingcap/tiflow/issues/8500) @[maxshuang](https://github.com/maxshuang) + + + TiDB Lightning + + - Fix the issue that when Physical Import Mode is used for importing data, if there is an `auto_random` column in the composite primary key of the target table, but the value of the column is not specified in the source data, TiDB Lightning does not generate data for the `auto_random` column automatically [#41454](https://github.com/pingcap/tidb/issues/41454) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that when Logical Import Mode is used for importing data, the import fails due to lack of the `CONFIG` permission for the target cluster [#41915](https://github.com/pingcap/tidb/issues/41915) @[lichunzhu](https://github.com/lichunzhu) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [AntiTopQuark](https://github.com/AntiTopQuark) +- [blacktear23](https://github.com/blacktear23) +- [BornChanger](https://github.com/BornChanger) +- [Dousir9](https://github.com/Dousir9) +- [erwadba](https://github.com/erwadba) +- [happy-v587](https://github.com/happy-v587) +- [jiyfhust](https://github.com/jiyfhust) +- [L-maple](https://github.com/L-maple) +- [liumengya94](https://github.com/liumengya94) +- [woofyzhao](https://github.com/woofyzhao) +- [xiaguan](https://github.com/xiaguan) diff --git a/releases/release-7.1.0.md b/releases/release-7.1.0.md new file mode 100644 index 0000000000000..cb7efe19f39e8 --- /dev/null +++ b/releases/release-7.1.0.md @@ -0,0 +1,551 @@ +--- +title: TiDB 7.1.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 7.1.0. +--- + +# TiDB 7.1.0 Release Notes + +Release date: May 31, 2023 + +TiDB version: 7.1.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.1/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.1/production-deployment-using-tiup) + +TiDB 7.1.0 is a Long-Term Support Release (LTS). + +Compared with the previous LTS 6.5.0, 7.1.0 not only includes new features, improvements, and bug fixes released in [6.6.0-DMR](/releases/release-6.6.0.md), [7.0.0-DMR](/releases/release-7.0.0.md), but also introduces the following key features and improvements: + +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeatureDescription
Scalability and PerformanceTiFlash supports the disaggregated storage and compute architecture and S3 shared storage (experimental, introduced in v7.0.0)TiFlash introduces a cloud-native architecture as an option: +
    +
  • Disaggregates TiFlash's compute and storage, which is a milestone for elastic HTAP resource utilization.
    • +
  • Introduces S3-based storage engine, which can provide shared storage at a lower cost.
    • +
+
TiKV supports batch aggregating data requests (introduced in v6.6.0) This enhancement significantly reduces total RPCs in TiKV batch-get operations. In situations where data is highly dispersed and the gRPC thread pool has insufficient resources, batching coprocessor requests can improve performance by more than 50%.
Load-based replica readIn a read hotspot scenario, TiDB can redirect read requests for a hotspot TiKV node to its replicas. This feature efficiently scatters read hotspots and optimizes the use of cluster resources. To control the threshold for triggering load-based replica read, you can adjust the system variable tidb_load_based_replica_read_threshold.
TiKV supports partitioned Raft KV storage engine (experimental)TiKV introduces a new generation of storage engine, the partitioned Raft KV. By allowing each data Region to have a dedicated RocksDB instance, it can expand the cluster's storage capacity from TB-level to PB-level and provide more stable write latency and stronger scalability.
Reliability and availabilityResource control by resource groups (GA)Support resource management based on resource groups, which allocates and isolates resources for different workloads in the same cluster. This feature significantly enhances the stability of multi-application clusters and lays the foundation for multi-tenancy. In v7.1.0, this feature introduces the ability to estimate system capacity based on actual workload or hardware deployment.
TiFlash supports spill to disk (introduced in v7.0.0)TiFlash supports intermediate result spill to disk to mitigate OOMs in data-intensive operations such as aggregations, sorts, and hash joins.
SQLMulti-valued indexes (GA)Support MySQL-compatible multi-valued indexes and enhance the JSON type to improve compatibility with MySQL 8.0. This feature improves the efficiency of membership checks on multi-valued columns.
Row-level TTL (GA in v7.0.0)Support managing database size and improve performance by automatically expiring data of a certain age.
Generated columns (GA)Values in a generated column are calculated by a SQL expression in the column definition in real time. This feature pushes some application logic to the database level, thus improving query efficiency.
SecurityLDAP authenticationTiDB supports LDAP authentication, which is compatible with MySQL 8.0.
Audit log enhancement (Enterprise Edition only)TiDB Enterprise Edition enhances the database auditing feature. It significantly improves the system auditing capacity by providing more fine-grained event filtering controls, more user-friendly filter settings, a new file output format in JSON, and lifecycle management of audit logs.
+ +## Feature details + +### Performance + +* Enhance the Partitioned Raft KV storage engine (experimental) [#11515](https://github.com/tikv/tikv/issues/11515) [#12842](https://github.com/tikv/tikv/issues/12842) @[busyjay](https://github.com/busyjay) @[tonyxuqqi](https://github.com/tonyxuqqi) @[tabokie](https://github.com/tabokie) @[bufferflies](https://github.com/bufferflies) @[5kbpers](https://github.com/5kbpers) @[SpadeA-Tang](https://github.com/SpadeA-Tang) @[nolouch](https://github.com/nolouch) + + TiDB v6.6.0 introduces the Partitioned Raft KV storage engine as an experimental feature, which uses multiple RocksDB instances to store TiKV Region data, and the data of each Region is independently stored in a separate RocksDB instance. The new storage engine can better control the number and level of files in the RocksDB instance, achieve physical isolation of data operations between Regions, and support stably managing more data. Compared with the original TiKV storage engine, using the Partitioned Raft KV storage engine can achieve about twice the write throughput and reduce the elastic scaling time by about 4/5 under the same hardware conditions and mixed read and write scenarios. + + In TiDB v7.1.0, the Partitioned Raft KV storage engine supports tools such as TiDB Lightning, BR, and TiCDC. + + Currently, this feature is experimental and not recommended for use in production environments. You can only use this engine in a newly created cluster and you cannot directly upgrade from the original TiKV storage engine. + + For more information, see [documentation](/partitioned-raft-kv.md). + +* TiFlash supports late materialization (GA) [#5829](https://github.com/pingcap/tiflash/issues/5829) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + + In v7.0.0, late materialization was introduced in TiFlash as an experimental feature for optimizing query performance. This feature is disabled by default (the [`tidb_opt_enable_late_materialization`](/system-variables.md#tidb_opt_enable_late_materialization-new-in-v700) system variable defaults to `OFF`). When processing a `SELECT` statement with filter conditions (`WHERE` clause), TiFlash reads all the data from the columns required by the query, and then filters and aggregates the data based on the query conditions. When Late materialization is enabled, TiDB supports pushing down part of the filter conditions to the TableScan operator. That is, TiFlash first scans the column data related to the filter conditions that are pushed down to the TableScan operator, filters the rows that meet the condition, and then scans the other column data of these rows for further calculation, thereby reducing IO scans and computations of data processing. + + Starting from v7.1.0, the TiFlash late materialization feature is generally available and enabled by default (the [`tidb_opt_enable_late_materialization`](/system-variables.md#tidb_opt_enable_late_materialization-new-in-v700) system variable defaults to `ON`). The TiDB optimizer decides which filters to be pushed down to the TableScan operator based on the statistics and the filter conditions of the query. + + For more information, see [documentation](/tiflash/tiflash-late-materialization.md). + +* TiFlash supports automatically choosing an MPP Join algorithm according to the overhead of network transmission [#7084](https://github.com/pingcap/tiflash/issues/7084) @[solotzg](https://github.com/solotzg) + + The TiFlash MPP mode supports multiple Join algorithms. Before v7.1.0, TiDB determines whether the MPP mode uses the Broadcast Hash Join algorithm based on the [`tidb_broadcast_join_threshold_count`](/system-variables.md#tidb_broadcast_join_threshold_count-new-in-v50) and [`tidb_broadcast_join_threshold_size`](/system-variables.md#tidb_broadcast_join_threshold_size-new-in-v50) variables and the actual data volume. + + In v7.1.0, TiDB introduces the [`tidb_prefer_broadcast_join_by_exchange_data_size`](/system-variables.md#tidb_prefer_broadcast_join_by_exchange_data_size-new-in-v710) variable, which controls whether to choose the MPP Join algorithm based on the minimum overhead of network transmission. This variable is disabled by default, indicating that the default algorithm selection method remains the same as that before v7.1.0. You can set the variable to `ON` to enable it. When it is enabled, you no longer need to manually adjust the [`tidb_broadcast_join_threshold_count`](/system-variables.md#tidb_broadcast_join_threshold_count-new-in-v50) and [`tidb_broadcast_join_threshold_size`](/system-variables.md#tidb_broadcast_join_threshold_size-new-in-v50) variables (both variables does not take effect at this time), TiDB automatically estimates the threshold of network transmission by different Join algorithms, and then chooses the algorithm with the smallest overhead overall, thus reducing network traffic and improving MPP query performance. + + For more information, see [documentation](/tiflash/use-tiflash-mpp-mode.md#algorithm-support-for-the-mpp-mode). + +* Support load-based replica read to mitigate read hotspots [#14151](https://github.com/tikv/tikv/issues/14151) @[sticnarf](https://github.com/sticnarf) @[you06](https://github.com/you06) + + In a read hotspot scenario, the hotspot TiKV node cannot process read requests in time, resulting in the read requests queuing. However, not all TiKV resources are exhausted at this time. To reduce latency, TiDB v7.1.0 introduces the load-based replica read feature, which allows TiDB to read data from other TiKV nodes without queuing on the hotspot TiKV node. You can control the queue length of read requests using the [`tidb_load_based_replica_read_threshold`](/system-variables.md#tidb_load_based_replica_read_threshold-new-in-v700) system variable. When the estimated queue time of the leader node exceeds this threshold, TiDB prioritizes reading data from follower nodes. This feature can improve read throughput by 70% to 200% in a read hotspot scenario compared to not scattering read hotspots. + + For more information, see [documentation](/troubleshoot-hot-spot-issues.md#scatter-read-hotspots). + +* Enhance the capability of caching execution plans for non-prepared statements (experimental) [#36598](https://github.com/pingcap/tidb/issues/36598) @[qw4990](https://github.com/qw4990) + + TiDB v7.0.0 introduces non-prepared plan cache as an experimental feature to improve the load capacity of concurrent OLTP. In v7.1.0, TiDB enhances this feature and supports caching more SQL statements. + + To improve memory utilization, TiDB v7.1.0 merges the cache pools of non-prepared and prepared plan caches. You can control the cache size using the system variable [`tidb_session_plan_cache_size`](/system-variables.md#tidb_session_plan_cache_size-new-in-v710). The [`tidb_prepared_plan_cache_size`](/system-variables.md#tidb_prepared_plan_cache_size-new-in-v610) and [`tidb_non_prepared_plan_cache_size`](/system-variables.md#tidb_non_prepared_plan_cache_size) system variables are deprecated. + + To maintain forward compatibility, when you upgrade from an earlier version to v7.1.0 or later versions, the cache size `tidb_session_plan_cache_size` remains the same value as `tidb_prepared_plan_cache_size`, and [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache) remains the setting before the upgrade. After sufficient performance testing, you can enable non-prepared plan cache using `tidb_enable_non_prepared_plan_cache`. For a newly created cluster, non-prepared plan cache is enabled by default. + + Non-prepared plan cache does not support DML statements by default. To remove this restriction, you can set the [`tidb_enable_non_prepared_plan_cache_for_dml`](/system-variables.md#tidb_enable_non_prepared_plan_cache_for_dml-new-in-v710) system variable to `ON`. + + For more information, see [documentation](/sql-non-prepared-plan-cache.md). + +* Support the TiDB Distributed eXecution Framework (DXF) (experimental) [#41495](https://github.com/pingcap/tidb/issues/41495) @[benjamin2037](https://github.com/benjamin2037) + + Before TiDB v7.1.0, only one TiDB node can serve as the DDL owner and execute DDL tasks at the same time. Starting from TiDB v7.1.0, in the new DXF, multiple TiDB nodes can execute the same DDL task in parallel, thus better utilizing the resources of the TiDB cluster and significantly improving the performance of DDL. In addition, you can linearly improve the performance of DDL by adding more TiDB nodes. Note that this feature is currently experimental and only supports `ADD INDEX` operations. + + To use the DXF, set the value of [`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710) to `ON`: + + ```sql + SET GLOBAL tidb_enable_dist_task = ON; + ``` + + For more information, see [documentation](/tidb-distributed-execution-framework.md). + +### Reliability + +* Resource Control becomes generally available (GA) [#38825](https://github.com/pingcap/tidb/issues/38825) @[nolouch](https://github.com/nolouch) @[BornChanger](https://github.com/BornChanger) @[glorv](https://github.com/glorv) @[tiancaiamao](https://github.com/tiancaiamao) @[Connor1996](https://github.com/Connor1996) @[JmPotato](https://github.com/JmPotato) @[hnes](https://github.com/hnes) @[CabinfeverB](https://github.com/CabinfeverB) @[HuSharp](https://github.com/HuSharp) + + TiDB enhances the resource control feature based on resource groups, which becomes GA in v7.1.0. This feature significantly improves the resource utilization efficiency and performance of TiDB clusters. The introduction of the resource control feature is a milestone for TiDB. You can divide a distributed database cluster into multiple logical units, map different database users to corresponding resource groups, and set the quota for each resource group as needed. When the cluster resources are limited, all resources used by sessions in the same resource group are limited to the quota. In this way, even if a resource group is over-consumed, the sessions in other resource groups are not affected. + + With this feature, you can combine multiple small and medium-sized applications from different systems into a single TiDB cluster. When the workload of an application grows larger, it does not affect the normal operation of other applications. When the system workload is low, busy applications can still be allocated the required system resources even if they exceed the set quotas, which can achieve the maximum utilization of resources. In addition, the rational use of the resource control feature can reduce the number of clusters, ease the difficulty of operation and maintenance, and save management costs. + + In TiDB v7.1.0, this feature introduces the ability to estimate system capacity based on actual workload or hardware deployment. The estimation ability provides you with a more accurate reference for capacity planning and assists you in better managing TiDB resource allocation to meet the stability needs of enterprise-level scenarios. + + To improve user experience, TiDB Dashboard provides the [Resource Manager page](/dashboard/dashboard-resource-manager.md). You can view the resource group configuration on this page and estimate cluster capacity in a visual way to facilitate reasonable resource allocation. + + For more information, see [documentation](/tidb-resource-control.md). + +* Support the checkpoint mechanism for Fast Online DDL to improve fault tolerance and automatic recovery capability [#42164](https://github.com/pingcap/tidb/issues/42164) @[tangenta](https://github.com/tangenta) + + TiDB v7.1.0 introduces a checkpoint mechanism for [Fast Online DDL](/ddl-introduction.md), which significantly improves the fault tolerance and automatic recovery capability of Fast Online DDL. Even if the TiDB owner node is restarted or changed due to failures, TiDB can still recover progress from checkpoints that are automatically updated on a regular basis, making the DDL execution more stable and efficient. + + For more information, see [documentation](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630). + +* Backup & Restore supports checkpoint restore [#42339](https://github.com/pingcap/tidb/issues/42339) @[Leavrth](https://github.com/Leavrth) + + Snapshot restore or log restore might be interrupted due to recoverable errors, such as disk exhaustion and node crash. Before TiDB v7.1.0, the recovery progress before the interruption would be invalidated even after the error is addressed, and you need to start the restore from scratch. For large clusters, this incurs considerable extra cost. + + Starting from TiDB v7.1.0, Backup & Restore (BR) introduces the checkpoint restore feature, which enables you to continue an interrupted restore. This feature can retain most recovery progress of the interrupted restore. + + For more information, see [documentation](/br/br-checkpoint-restore.md). + +* Optimize the strategy of loading statistics [#42160](https://github.com/pingcap/tidb/issues/42160) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + TiDB v7.1.0 introduces lightweight statistics initialization as an experimental feature. Lightweight statistics initialization can significantly reduce the number of statistics that must be loaded during startup, thus improving the speed of loading statistics. This feature increases the stability of TiDB in complex runtime environments and reduces the impact on the overall service when TiDB nodes restart. You can set the parameter [`lite-init-stats`](/tidb-configuration-file.md#lite-init-stats-new-in-v710) to `true` to enable this feature. + + During TiDB startup, SQL statements executed before the initial statistics are fully loaded might have suboptimal execution plans, thus causing performance issues. To avoid such issues, TiDB v7.1.0 introduces the configuration parameter [`force-init-stats`](/tidb-configuration-file.md#force-init-stats-new-in-v657-and-v710). With this option, you can control whether TiDB provides services only after statistics initialization has been finished during startup. This parameter is disabled by default. + + For more information, see [documentation](/statistics.md#load-statistics). + +* TiCDC supports the data integrity validation feature for single-row data [#8718](https://github.com/pingcap/tiflow/issues/8718) [#42747](https://github.com/pingcap/tidb/issues/42747) @[3AceShowHand](https://github.com/3AceShowHand) @[zyguan](https://github.com/zyguan) + + Starting from v7.1.0, TiCDC introduces the data integrity validation feature, which uses a checksum algorithm to validate the integrity of single-row data. This feature helps verify whether any error occurs in the process of writing data from TiDB, replicating it through TiCDC, and then writing it to a Kafka cluster. The data integrity validation feature only supports changefeeds that use Kafka as the downstream and currently supports the Avro protocol. + + For more information, see [documentation](/ticdc/ticdc-integrity-check.md). + +* TiCDC optimizes DDL replication operations [#8686](https://github.com/pingcap/tiflow/issues/8686) @[hi-rustin](https://github.com/Rustin170506) + + Before v7.1.0, when you perform a DDL operation that affects all rows on a large table (such as adding or deleting a column), the replication latency of TiCDC would significantly increase. Starting from v7.1.0, TiCDC optimizes this replication operation and mitigates the impact of DDL operations on downstream latency. + + For more information, see [documentation](/ticdc/ticdc-faq.md#does-ticdc-replicate-data-changes-caused-by-lossy-ddl-operations-to-the-downstream). + +* Improve the stability of TiDB Lightning when importing TiB-level data [#43510](https://github.com/pingcap/tidb/issues/43510) [#43657](https://github.com/pingcap/tidb/issues/43657) @[D3Hunter](https://github.com/D3Hunter) @[lance6716](https://github.com/lance6716) + + Starting from v7.1.0, TiDB Lightning has added four configuration items to improve stability when importing TiB-level data. + + - `tikv-importer.region-split-batch-size` controls the number of Regions when splitting Regions in a batch. The default value is `4096`. + - `tikv-importer.region-split-concurrency` controls the concurrency when splitting Regions. The default value is the number of CPU cores. + - `tikv-importer.region-check-backoff-limit` controls the number of retries to wait for the Region to come online after the split and scatter operations. The default value is `1800` and the maximum retry interval is two seconds. The number of retries is not increased if any Region becomes online between retries. + - `tikv-importer.pause-pd-scheduler-scope` controls the scope in which TiDB Lightning pauses PD scheduling. Value options are `"table"` and `"global"`. The default value is `"table"`. For TiDB versions earlier than v6.1.0, you can only configure the `"global"` option, which pauses global scheduling during data import. Starting from v6.1.0, the `"table"` option is supported, which means that scheduling is only paused for the Region that stores the target table data. It is recommended to set this configuration item to `"global"` in scenarios with large data volumes to improve stability. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md). + +### SQL + +* Support saving TiFlash query results using the `INSERT INTO SELECT` statement (GA) [#37515](https://github.com/pingcap/tidb/issues/37515) @[gengliqi](https://github.com/gengliqi) + + Starting from v6.5.0, TiDB supports pushing down the `SELECT` clause (analytical query) of the `INSERT INTO SELECT` statement to TiFlash. In this way, you can easily save the TiFlash query result to a TiDB table specified by `INSERT INTO` for further analysis, which takes effect as result caching (that is, result materialization). + + In v7.1.0, this feature is generally available. During the execution of the `SELECT` clause in the `INSERT INTO SELECT` statement, the optimizer can intelligently decide whether to push a query down to TiFlash based on the [SQL mode](/sql-mode.md) and the cost estimates of the TiFlash replica. Therefore, the `tidb_enable_tiflash_read_for_write_stmt` system variable introduced during the experimental phase is now deprecated. Note that the computation rules of `INSERT INTO SELECT` statements for TiFlash do not meet the `STRICT SQL Mode` requirement, so TiDB allows the `SELECT` clause in the `INSERT INTO SELECT` statement to be pushed down to TiFlash only when the [SQL mode](/sql-mode.md) of the current session is not strict, which means that the `sql_mode` value does not contain `STRICT_TRANS_TABLES` and `STRICT_ALL_TABLES`. + + For more information, see [documentation](/tiflash/tiflash-results-materialization.md). + +* MySQL-compatible multi-valued indexes become generally available (GA) [#39592](https://github.com/pingcap/tidb/issues/39592) @[xiongjiwei](https://github.com/xiongjiwei) @[qw4990](https://github.com/qw4990) @[YangKeao](https://github.com/YangKeao) + + Filtering the values of an array in a JSON column is a common operation, but normal indexes cannot help speed up such an operation. Creating a multi-valued index on an array can greatly improve filtering performance. If an array in the JSON column has a multi-valued index, you can use the multi-valued index to filter retrieval conditions in `MEMBER OF()`, `JSON_CONTAINS()`, and `JSON_OVERLAPS()` functions, thereby reducing I/O consumption and improving operation speed. + + In v7.1.0, the multi-valued indexes feature becomes generally available (GA). It supports more complete data types and is compatible with TiDB tools. You can use multi-valued indexes to speed up the search operations on JSON arrays in production environments. + + For more information, see [documentation](/sql-statements/sql-statement-create-index.md#multi-valued-indexes). + +* Improve the partition management for Hash and Key partitioned tables [#42728](https://github.com/pingcap/tidb/issues/42728) @[mjonss](https://github.com/mjonss) + + Before v7.1.0, Hash and Key partitioned tables in TiDB only support the `TRUNCATE PARTITION` partition management statement. Starting from v7.1.0, Hash and Key partitioned tables also support `ADD PARTITION` and `COALESCE PARTITION` partition management statements. Therefore, you can flexibly adjust the number of partitions in Hash and Key partitioned tables as needed. For example, you can increase the number of partitions with the `ADD PARTITION` statement, or decrease the number of partitions with the `COALESCE PARTITION` statement. + + For more information, see [documentation](/partitioned-table.md#manage-hash-and-key-partitions). + +* The syntax of Range INTERVAL partitioning becomes generally available (GA) [#35683](https://github.com/pingcap/tidb/issues/35683) @[mjonss](https://github.com/mjonss) + + The syntax of Range INTERVAL partitioning (introduced in v6.3.0) becomes GA. With this syntax, you can define Range partitioning by a desired interval without enumerating all partitions, which drastically reduces the length of Range partitioning DDL statements. The syntax is equivalent to that of the original Range partitioning. + + For more information, see [documentation](/partitioned-table.md#range-interval-partitioning). + +* Generated columns become generally available (GA) @[bb7133](https://github.com/bb7133) + + Generated columns are a valuable feature for a database. When creating a table, you can define that the value of a column is calculated based on the values of other columns in the table, rather than being explicitly inserted or updated by users. This generated column can be either a virtual column or a stored column. TiDB has supported MySQL-compatible generated columns since earlier versions, and this feature becomes GA in v7.1.0. + + Using generated columns can improve MySQL compatibility for TiDB, simplifying the process of migrating from MySQL. It also reduces data maintenance complexity and improves data consistency and query efficiency. + + For more information, see [documentation](/generated-columns.md). + +### DB operations + +* Support smooth cluster upgrade without manually canceling DDL operations (experimental) [#39751](https://github.com/pingcap/tidb/issues/39751) @[zimulala](https://github.com/zimulala) + + Before TiDB v7.1.0, to upgrade a cluster, you must manually cancel its running or queued DDL tasks before the upgrade and then add them back after the upgrade. + + To provide a smoother upgrade experience, TiDB v7.1.0 supports automatically pausing and resuming DDL tasks. Starting from v7.1.0, you can upgrade your clusters without manually canceling DDL tasks in advance. TiDB will automatically pause any running or queued user DDL tasks before the upgrade and resume these tasks after the rolling upgrade, making it easier for you to upgrade your TiDB clusters. + + For more information, see [documentation](/smooth-upgrade-tidb.md). + +### Observability + +* Enhance optimizer diagnostic information [#43122](https://github.com/pingcap/tidb/issues/43122) @[time-and-fate](https://github.com/time-and-fate) + + Obtaining sufficient information is the key to SQL performance diagnostics. In v7.1.0, TiDB continues to add optimizer runtime information to various diagnostic tools, providing better insights into how execution plans are selected and assisting in troubleshooting SQL performance issues. The new information includes: + + * `debug_trace.json` in the output of [`PLAN REPLAYER`](/sql-plan-replayer.md). + * Partial statistics details for `operator info` in the output of [`EXPLAIN`](/explain-walkthrough.md). + * Partial statistics details in the `Stats` field of [slow queries](/identify-slow-queries.md). + + For more information, see [Use `PLAN REPLAYER` to save and restore the on-site information of a cluster](/sql-plan-replayer.md), [`EXPLAIN` walkthrough](/explain-walkthrough.md), and [Identify slow queries](/identify-slow-queries.md). + +### Security + +* Replace the interface used for querying TiFlash system table information [#6941](https://github.com/pingcap/tiflash/issues/6941) @[flowbehappy](https://github.com/flowbehappy) + + Starting from v7.1.0, when providing the query service of [`INFORMATION_SCHEMA.TIFLASH_TABLES`](/information-schema/information-schema-tiflash-tables.md) and [`INFORMATION_SCHEMA.TIFLASH_SEGMENTS`](/information-schema/information-schema-tiflash-segments.md) system tables for TiDB, TiFlash uses the gRPC port instead of the HTTP port, which avoids the security risks of the HTTP service. + +* Support LDAP authentication [#43580](https://github.com/pingcap/tidb/issues/43580) @[YangKeao](https://github.com/YangKeao) + + Starting from v7.1.0, TiDB supports LDAP authentication and provides two authentication plugins: `authentication_ldap_sasl` and `authentication_ldap_simple`. + + For more information, see [documentation](/security-compatibility-with-mysql.md). + +* Enhance the database auditing feature (Enterprise Edition) + + In v7.1.0, TiDB Enterprise Edition enhances the database auditing feature, which significantly expands its capacity and improves the user experience to meet the needs of enterprises for database security compliance: + + - Introduce the concepts of "Filter" and "Rule" for more granular audit event definitions and more fine-grained audit settings. + - Support defining rules in JSON format, providing a more user-friendly configuration method. + - Add automatic log rotation and space management functions, and support configuring log rotation in two dimensions: retention time and log size. + - Support outputting audit logs in both TEXT and JSON formats, facilitating easier integration with third-party tools. + - Support audit log redaction. You can replace all literals to enhance security. + + Database auditing is an important feature in TiDB Enterprise Edition. This feature provides a powerful monitoring and auditing tool for enterprises to ensure data security and compliance. It can help enterprise managers in tracking the source and impact of database operations to prevent illegal data theft or tampering. Furthermore, database auditing can also help enterprises meet various regulatory and compliance requirements, ensuring legal and ethical compliance. This feature has important application value for enterprise information security. + + For more information, see [user guide](https://static.pingcap.com/files/2023/09/18204824/TiDB-Database-Auditing-User-Guide1.pdf). This feature is included in TiDB Enterprise Edition. To use this feature, navigate to the [TiDB Enterprise](https://www.pingcap.com/tidb-enterprise) page to get TiDB Enterprise Edition. + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v7.0.0 to the current version (v7.1.0). If you are upgrading from v6.6.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### Behavior changes + +* To improve security, TiFlash deprecates the HTTP service port (default `8123`) and uses the gRPC port as a replacement + + If you have upgraded TiFlash to v7.1.0, then during the TiDB upgrade to v7.1.0, TiDB cannot read the TiFlash system tables ([`INFORMATION_SCHEMA.TIFLASH_TABLES`](/information-schema/information-schema-tiflash-tables.md) and [`INFORMATION_SCHEMA.TIFLASH_SEGMENTS`](/information-schema/information-schema-tiflash-segments.md)). + +* TiDB Lightning in TiDB versions from v6.2.0 to v7.0.0 decides whether to pause global scheduling based on the TiDB cluster version. When TiDB cluster version >= v6.1.0, scheduling is only paused for the Region that stores the target table data and is resumed after the target table import is complete. While for other versions, TiDB Lightning pauses global scheduling. Starting from TiDB v7.1.0, you can control whether to pause global scheduling by configuring [`pause-pd-scheduler-scope`](/tidb-lightning/tidb-lightning-configuration.md). By default, TiDB Lightning pauses scheduling for the Region that stores the target table data. If the target cluster version is earlier than v6.1.0, an error occurs. In this case, you can change the value of the parameter to `"global"` and try again. + +* When you use [`FLASHBACK CLUSTER TO TIMESTAMP`](/sql-statements/sql-statement-flashback-cluster.md) in TiDB v7.1.0, some Regions might remain in the FLASHBACK process even after the completion of the FLASHBACK operation. It is recommended to avoid using this feature in v7.1.0. For more information, see issue [#44292](https://github.com/pingcap/tidb/issues/44292). If you have encountered this issue, you can use the [TiDB snapshot backup and restore](/br/br-snapshot-guide.md) feature to restore data. + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_enable_tiflash_read_for_write_stmt`](/system-variables.md#tidb_enable_tiflash_read_for_write_stmt-new-in-v630) | Deprecated | Changes the default value from `OFF` to `ON`. When [`tidb_allow_mpp = ON`](/system-variables.md#tidb_allow_mpp-new-in-v50), the optimizer intelligently decides whether to push a query down to TiFlash based on the [SQL mode](/sql-mode.md) and the cost estimates of the TiFlash replica. | +| [`tidb_non_prepared_plan_cache_size`](/system-variables.md#tidb_non_prepared_plan_cache_size) | Deprecated | Starting from v7.1.0, this system variable is deprecated. You can use [`tidb_session_plan_cache_size`](/system-variables.md#tidb_session_plan_cache_size-new-in-v710) to control the maximum number of plans that can be cached. | +| [`tidb_prepared_plan_cache_size`](/system-variables.md#tidb_prepared_plan_cache_size-new-in-v610) | Deprecated | Starting from v7.1.0, this system variable is deprecated. You can use [`tidb_session_plan_cache_size`](/system-variables.md#tidb_session_plan_cache_size-new-in-v710) to control the maximum number of plans that can be cached. | +| `tidb_ddl_distribute_reorg` | Deleted | This variable is renamed to [`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710). | +| [`default_authentication_plugin`](/system-variables.md#default_authentication_plugin) | Modified | Introduces two new value options: `authentication_ldap_sasl` and `authentication_ldap_simple`. | +| [`tidb_load_based_replica_read_threshold`](/system-variables.md#tidb_load_based_replica_read_threshold-new-in-v700) | Modified | Takes effect starting from v7.1.0 and controls the threshold for triggering load-based replica read. Changes the default value from `"0s"` to `"1s"` after further tests. | +| [`tidb_opt_enable_late_materialization`](/system-variables.md#tidb_opt_enable_late_materialization-new-in-v700) | Modified | Changes the default value from `OFF` to `ON`, meaning that the TiFlash late materialization feature is enabled by default. | +| [`authentication_ldap_sasl_auth_method_name`](/system-variables.md#authentication_ldap_sasl_auth_method_name-new-in-v710) | Newly added | Specifies the authentication method name in LDAP SASL authentication. | +| [`authentication_ldap_sasl_bind_base_dn`](/system-variables.md#authentication_ldap_sasl_bind_base_dn-new-in-v710) | Newly added | Limits the search scope within the search tree in LDAP SASL authentication. If a user is created without `AS ...` clause, TiDB automatically searches the `dn` in LDAP server according to the user name. | +| [`authentication_ldap_sasl_bind_root_dn`](/system-variables.md#authentication_ldap_sasl_bind_root_dn-new-in-v710) | Newly added | Specifies the `dn` used to login to the LDAP server to search users in LDAP SASL authentication. | +| [`authentication_ldap_sasl_bind_root_pwd`](/system-variables.md#authentication_ldap_sasl_bind_root_pwd-new-in-v710) | Newly added | Specifies the password used to login to the LDAP server to search users in LDAP SASL authentication. | +| [`authentication_ldap_sasl_ca_path`](/system-variables.md#authentication_ldap_sasl_ca_path-new-in-v710) | Newly added | Specifies the absolute path of the certificate authority file for StartTLS connections in LDAP SASL authentication. | +| [`authentication_ldap_sasl_init_pool_size`](/system-variables.md#authentication_ldap_sasl_init_pool_size-new-in-v710) | Newly added | Specifies the initial connections in the connection pool to the LDAP server in LDAP SASL authentication. | +| [`authentication_ldap_sasl_max_pool_size`](/system-variables.md#authentication_ldap_sasl_max_pool_size-new-in-v710) | Newly added | Specifies the maximum connections in the connection pool to the LDAP server in LDAP SASL authentication. | +| [`authentication_ldap_sasl_server_host`](/system-variables.md#authentication_ldap_sasl_server_host-new-in-v710) | Newly added | Specifies the LDAP server host in LDAP SASL authentication. | +| [`authentication_ldap_sasl_server_port`](/system-variables.md#authentication_ldap_sasl_server_port-new-in-v710) | Newly added | Specifies the LDAP server TCP/IP port number in LDAP SASL authentication. | +| [`authentication_ldap_sasl_tls`](/system-variables.md#authentication_ldap_sasl_tls-new-in-v710) | Newly added | Specifies whether connections by the plugin to the LDAP server are protected with StartTLS in LDAP SASL authentication. | +| [`authentication_ldap_simple_auth_method_name`](/system-variables.md#authentication_ldap_simple_auth_method_name-new-in-v710) | Newly added | Specifies the authentication method name in LDAP simple authentication. It only supports `SIMPLE`. | +| [`authentication_ldap_simple_bind_base_dn`](/system-variables.md#authentication_ldap_simple_bind_base_dn-new-in-v710) | Newly added | Limits the search scope within the search tree in LDAP simple authentication. If a user is created without `AS ...` clause, TiDB will automatically search the `dn` in LDAP server according to the user name. | +| [`authentication_ldap_simple_bind_root_dn`](/system-variables.md#authentication_ldap_simple_bind_root_dn-new-in-v710) | Newly added | Specifies the `dn` used to login to the LDAP server to search users in LDAP simple authentication. | +| [`authentication_ldap_simple_bind_root_pwd`](/system-variables.md#authentication_ldap_simple_bind_root_pwd-new-in-v710) | Newly added | Specifies the password used to login to the LDAP server to search users in LDAP simple authentication. | +| [`authentication_ldap_simple_ca_path`](/system-variables.md#authentication_ldap_simple_ca_path-new-in-v710) | Newly added | Specifies the absolute path of the certificate authority file for StartTLS connections in LDAP simple authentication. | +| [`authentication_ldap_simple_init_pool_size`](/system-variables.md#authentication_ldap_simple_init_pool_size-new-in-v710) | Newly added | Specifies the initial connections in the connection pool to the LDAP server in LDAP simple authentication. | +| [`authentication_ldap_simple_max_pool_size`](/system-variables.md#authentication_ldap_simple_max_pool_size-new-in-v710) | Newly added | Specifies the maximum connections in the connection pool to the LDAP server in LDAP simple authentication. | +| [`authentication_ldap_simple_server_host`](/system-variables.md#authentication_ldap_simple_server_host-new-in-v710) | Newly added | Specifies the LDAP server host in LDAP simple authentication. | +| [`authentication_ldap_simple_server_port`](/system-variables.md#authentication_ldap_simple_server_port-new-in-v710) | Newly added | Specifies the LDAP server TCP/IP port number in LDAP simple authentication. | +| [`authentication_ldap_simple_tls`](/system-variables.md#authentication_ldap_simple_tls-new-in-v710) | Newly added | Specifies whether connections by the plugin to the LDAP server are protected with StartTLS in LDAP simple authentication. | +| [`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710) | Newly added | Controls whether to enable the Distributed eXecution Framework (DXF). After enabling the DXF, DDL, import, and other supported DXF tasks will be jointly completed by multiple TiDB nodes in the cluster. This variable was renamed from `tidb_ddl_distribute_reorg`. | +| [`tidb_enable_non_prepared_plan_cache_for_dml`](/system-variables.md#tidb_enable_non_prepared_plan_cache_for_dml-new-in-v710) | Newly added | Controls whether to enable the [Non-prepared plan cache](/sql-non-prepared-plan-cache.md) feature for DML statements. | +| [`tidb_enable_row_level_checksum`](/system-variables.md#tidb_enable_row_level_checksum-new-in-v710) | Newly added | Controls whether to enable the TiCDC data integrity validation for single-row data feature.| +| [`tidb_opt_fix_control`](/system-variables.md#tidb_opt_fix_control-new-in-v653-and-v710) | Newly added | This variable provides more fine-grained control over the optimizer and helps to prevent performance regression after upgrading caused by behavior changes in the optimizer. | +| [`tidb_plan_cache_invalidation_on_fresh_stats`](/system-variables.md#tidb_plan_cache_invalidation_on_fresh_stats-new-in-v710) | Newly added | Controls whether to invalidate the plan cache automatically when statistics on related tables are updated. | +| [`tidb_plan_cache_max_plan_size`](/system-variables.md#tidb_plan_cache_max_plan_size-new-in-v710) | Newly added | Controls the maximum size of a plan that can be cached in prepared or non-prepared plan cache. | +| [`tidb_prefer_broadcast_join_by_exchange_data_size`](/system-variables.md#tidb_prefer_broadcast_join_by_exchange_data_size-new-in-v710) | Newly added | Controls whether to use the algorithm with the minimum overhead of network transmission. If this variable is enabled, TiDB estimates the size of the data to be exchanged in the network using `Broadcast Hash Join` and `Shuffled Hash Join` respectively, and then chooses the one with the smaller size. [`tidb_broadcast_join_threshold_count`](/system-variables.md#tidb_broadcast_join_threshold_count-new-in-v50) and [`tidb_broadcast_join_threshold_size`](/system-variables.md#tidb_broadcast_join_threshold_size-new-in-v50) will not take effect after this variable is enabled. | +| [`tidb_session_plan_cache_size`](/system-variables.md#tidb_session_plan_cache_size-new-in-v710) | Newly added | Controls the maximum number of plans that can be cached. Prepared plan cache and non-prepared plan cache share the same cache. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`performance.force-init-stats`](/tidb-configuration-file.md#force-init-stats-new-in-v657-and-v710) | Newly added | Controls whether to wait for statistics initialization to finish before providing services during TiDB startup. | +| TiDB | [`performance.lite-init-stats`](/tidb-configuration-file.md#lite-init-stats-new-in-v710) | Newly added | Controls whether to use lightweight statistics initialization during TiDB startup. | +| TiDB | [`log.timeout`](/tidb-configuration-file.md#timeout-new-in-v710) | Newly added | Sets the timeout for log-writing operations in TiDB. In case of a disk failure that prevents logs from being written, this configuration item can trigger the TiDB process to panic instead of hang. The default value is `0`, which means no timeout is set. | +| TiKV | [`region-compact-min-redundant-rows`](/tikv-configuration-file.md#region-compact-min-redundant-rows-new-in-v710) | Newly added | Sets the number of redundant MVCC rows required to trigger RocksDB compaction. The default value is `50000`. | +| TiKV | [`region-compact-redundant-rows-percent`](/tikv-configuration-file.md#region-compact-redundant-rows-percent-new-in-v710) | Newly added | Sets the percentage of redundant MVCC rows required to trigger RocksDB compaction. The default value is `20`. | +| TiKV | [`split.byte-threshold`](/tikv-configuration-file.md#byte-threshold-new-in-v50) | Modified | Changes the default value from `30MiB` to `100MiB` when [`region-split-size`](/tikv-configuration-file.md#region-split-size) is greater than or equal to 4 GB. | +| TiKV | [`split.qps-threshold`](/tikv-configuration-file.md#qps-threshold) | Modified | Changes the default value from `3000` to `7000` when [`region-split-size`](/tikv-configuration-file.md#region-split-size) is greater than or equal to 4 GB. | +| TiKV | [`split.region-cpu-overload-threshold-ratio`](/tikv-configuration-file.md#region-cpu-overload-threshold-ratio-new-in-v620) | Modified | Changes the default value from `0.25` to `0.75` when [`region-split-size`](/tikv-configuration-file.md#region-split-size) is greater than or equal to 4 GB. | +| TiKV | [`region-compact-check-step`](/tikv-configuration-file.md#region-compact-check-step) | Modified | Changes the default value from `100` to `5` when Partitioned Raft KV is enabled (`storage.engine="partitioned-raft-kv"`). | +| PD | [`store-limit-version`](/pd-configuration-file.md#store-limit-version-new-in-v710) | Newly added | Controls the mode of store limit. Value options are `"v1"` and `"v2"`. | +| PD | [`schedule.enable-diagnostic`](/pd-configuration-file.md#enable-diagnostic-new-in-v630) | Modified | Changes the default value from `false` to `true`, meaning that the diagnostic feature of scheduler is enabled by default. | +| TiFlash | `http_port` | Deleted | Deprecates the HTTP service port (default `8123`). | +| TiDB Lightning | [`tikv-importer.pause-pd-scheduler-scope`](/tidb-lightning/tidb-lightning-configuration.md) | Newly added | Controls the scope in which TiDB Lightning pauses PD scheduling. The default value is `"table"` and value options are `"global"` and `"table"`. | +| TiDB Lightning | [`tikv-importer.region-check-backoff-limit`](/tidb-lightning/tidb-lightning-configuration.md) | Newly added | Controls the number of retries to wait for the Region to come online after the split and scatter operations. The default value is `1800`. The maximum retry interval is two seconds. The number of retries is not increased if any Region becomes online between retries.| +| TiDB Lightning | [`tikv-importer.region-split-batch-size`](/tidb-lightning/tidb-lightning-configuration.md) | Newly added | Controls the number of Regions when splitting Regions in a batch. The default value is `4096`. | +| TiDB Lightning | [`tikv-importer.region-split-concurrency`](/tidb-lightning/tidb-lightning-configuration.md) | Newly added | Controls the concurrency when splitting Regions. The default value is the number of CPU cores. | +| TiCDC | [`insecure-skip-verify`](/ticdc/ticdc-sink-to-kafka.md) | Newly added | Controls whether the authentication algorithm is set when TLS is enabled in the scenario of replicating data to Kafka. | +| TiCDC | [`integrity.corruption-handle-level`](/ticdc/ticdc-changefeed-config.md#cli-and-configuration-parameters-of-ticdc-changefeeds) | Newly added | Specifies the log level of the Changefeed when the checksum validation for single-row data fails. The default value is `"warn"`. Value options are `"warn"` and `"error"`. | +| TiCDC | [`integrity.integrity-check-level`](/ticdc/ticdc-changefeed-config.md#cli-and-configuration-parameters-of-ticdc-changefeeds) | Newly added | Controls whether to enable the checksum validation for single-row data. The default value is `"none"`, which means to disable the feature. | +| TiCDC | [`sink.only-output-updated-columns`](/ticdc/ticdc-changefeed-config.md#cli-and-configuration-parameters-of-ticdc-changefeeds) | Newly added | Controls whether to only output the updated columns. The default value is `false`. | +| TiCDC | [`sink.enable-partition-separator`](/ticdc/ticdc-changefeed-config.md#cli-and-configuration-parameters-of-ticdc-changefeeds) | Modified | Changes the default value from `false` to `true` after further tests, meaning that partitions in a table are stored in separate directories by default. It is recommended that you keep the value as `true` to avoid the potential issue of data loss during replication of partitioned tables to storage services. | + +## Improvements + ++ TiDB + + - Display the number of distinct values for the corresponding column in the Cardinality column of the `SHOW INDEX` result [#42227](https://github.com/pingcap/tidb/issues/42227) @[winoros](https://github.com/winoros) + - Use `SQL_NO_CACHE` to prevent TTL Scan queries from impacting the TiKV block cache [#43206](https://github.com/pingcap/tidb/issues/43206) @[lcwangchao](https://github.com/lcwangchao) + - Improve an error message related to `MAX_EXECUTION_TIME` to make it compatible with MySQL [#43031](https://github.com/pingcap/tidb/issues/43031) @[dveeden](https://github.com/dveeden) + - Support using the MergeSort operator on partitioned tables in IndexLookUp [#26166](https://github.com/pingcap/tidb/issues/26166) @[Defined2014](https://github.com/Defined2014) + - Enhance `caching_sha2_password` to make it compatible with MySQL [#43576](https://github.com/pingcap/tidb/issues/43576) @[asjdf](https://github.com/asjdf) + ++ TiKV + + - Reduce the impact of split operations on write QPS when using partitioned Raft KV [#14447](https://github.com/tikv/tikv/issues/14447) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + - Optimize the space occupied by snapshots when using partitioned Raft KV [#14581](https://github.com/tikv/tikv/issues/14581) @[bufferflies](https://github.com/bufferflies) + - Provide more detailed time information for each stage of processing requests in TiKV [#12362](https://github.com/tikv/tikv/issues/12362) @[cfzjywxk](https://github.com/cfzjywxk) + - Use PD as metastore in log backup [#13867](https://github.com/tikv/tikv/issues/13867) @[YuJuncen](https://github.com/YuJuncen) + ++ PD + + - Add a controller that automatically adjusts the size of the store limit based on the execution details of the snapshot. To enable this controller, set `store-limit-version` to `v2`. Once enabled, you do not need to manually adjust the `store limit` configuration to control the speed of scaling in or scaling out [#6147](https://github.com/tikv/pd/issues/6147) @[bufferflies](https://github.com/bufferflies) + - Add historical load information to avoid frequent scheduling of Regions with unstable loads by the hotspot scheduler when the storage engine is raft-kv2 [#6297](https://github.com/tikv/pd/issues/6297) @[bufferflies](https://github.com/bufferflies) + - Add a leader health check mechanism. When the PD server where the etcd leader is located cannot be elected as the leader, PD actively switches the etcd leader to ensure that the PD leader is available [#6403](https://github.com/tikv/pd/issues/6403) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Improve TiFlash performance and stability in the disaggregated storage and compute architecture [#6882](https://github.com/pingcap/tiflash/issues/6882) @[JaySon-Huang](https://github.com/JaySon-Huang) @[breezewish](https://github.com/breezewish) @[JinheLin](https://github.com/JinheLin) + - Support optimizing query performance in Semi Join or Anti Semi Join by selecting the smaller table as the build side [#7280](https://github.com/pingcap/tiflash/issues/7280) @[yibin87](https://github.com/yibin87) + - Improve performance of data import from BR and TiDB Lightning to TiFlash with default configurations [#7272](https://github.com/pingcap/tiflash/issues/7272) @[breezewish](https://github.com/breezewish) + ++ Tools + + + Backup & Restore (BR) + + - Support modifying the TiKV configuration item `log-backup.max-flush-interval` during log backup [#14433](https://github.com/tikv/tikv/issues/14433) @[joccau](https://github.com/joccau) + + + TiCDC + + - Optimize the directory structure when DDL events occur in the scenario of replicating data to object storage [#8890](https://github.com/pingcap/tiflow/issues/8890) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Optimize the method of setting GC TLS for the upstream when the TiCDC replication task fails [#8403](https://github.com/pingcap/tiflow/issues/8403) @[charleszheng44](https://github.com/charleszheng44) + - Support replicating data to the Kafka-on-Pulsar downstream [#8892](https://github.com/pingcap/tiflow/issues/8892) @[hi-rustin](https://github.com/Rustin170506) + - Support using the open-protocol protocol to only replicate the changed columns after an update occurs when replicating data to Kafka [#8706](https://github.com/pingcap/tiflow/issues/8706) @[sdojjy](https://github.com/sdojjy) + - Optimize the error handling of TiCDC in the downstream failures or other scenarios [#8657](https://github.com/pingcap/tiflow/issues/8657) @[hicqu](https://github.com/hicqu) + - Add a configuration item `insecure-skip-verify` to control whether to set the authentication algorithm in the scenario of enabling TLS [#8867](https://github.com/pingcap/tiflow/issues/8867) @[hi-rustin](https://github.com/Rustin170506) + + + TiDB Lightning + + - Change the severity level of the precheck item related to uneven Region distribution from `Critical` to `Warn` to avoid blocking users from importing data [#42836](https://github.com/pingcap/tidb/issues/42836) @[okJiang](https://github.com/okJiang) + - Add a retry mechanism when encountering an `unknown RPC` error during data import [#43291](https://github.com/pingcap/tidb/issues/43291) @[D3Hunter](https://github.com/D3Hunter) + - Enhance the retry mechanism for Region jobs [#43682](https://github.com/pingcap/tidb/issues/43682) @[lance6716](https://github.com/lance6716) + +## Bug fixes + ++ TiDB + + - Fix the issue that there is no prompt about manually executing `ANALYZE TABLE` after reorganizing partitions [#42183](https://github.com/pingcap/tidb/issues/42183) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue of missing table names in the `ADMIN SHOW DDL JOBS` result when a `DROP TABLE` operation is being executed [#42268](https://github.com/pingcap/tidb/issues/42268) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that `Ignore Event Per Minute` and `Stats Cache LRU Cost` charts might not be displayed normally in the Grafana monitoring panel [#42562](https://github.com/pingcap/tidb/issues/42562) @[pingandb](https://github.com/pingandb) + - Fix the issue that the `ORDINAL_POSITION` column returns incorrect results when querying the `INFORMATION_SCHEMA.COLUMNS` table [#43379](https://github.com/pingcap/tidb/issues/43379) @[bb7133](https://github.com/bb7133) + - Fix the case sensitivity issue in some columns of the permission table [#41048](https://github.com/pingcap/tidb/issues/41048) @[bb7133](https://github.com/bb7133) + - Fix the issue that after a new column is added in the cache table, the value is `NULL` instead of the default value of the column [#42928](https://github.com/pingcap/tidb/issues/42928) @[lqs](https://github.com/lqs) + - Fix the issue that CTE results are incorrect when pushing down predicates [#43645](https://github.com/pingcap/tidb/issues/43645) @[winoros](https://github.com/winoros) + - Fix the issue of DDL retry caused by write conflict when executing `TRUNCATE TABLE` for partitioned tables with many partitions and TiFlash replicas [#42940](https://github.com/pingcap/tidb/issues/42940) @[mjonss](https://github.com/mjonss) + - Fix the issue that there is no warning when using `SUBPARTITION` in creating partitioned tables [#41198](https://github.com/pingcap/tidb/issues/41198) [#41200](https://github.com/pingcap/tidb/issues/41200) @[mjonss](https://github.com/mjonss) + - Fix the incompatibility issue with MySQL when dealing with value overflow issues in generated columns [#40066](https://github.com/pingcap/tidb/issues/40066) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that `REORGANIZE PARTITION` cannot be concurrently executed with other DDL operations [#42442](https://github.com/pingcap/tidb/issues/42442) @[bb7133](https://github.com/bb7133) + - Fix the issue that canceling the partition reorganization task in DDL might cause subsequent DDL operations to fail [#42448](https://github.com/pingcap/tidb/issues/42448) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that assertions on delete operations are incorrect under certain conditions [#42426](https://github.com/pingcap/tidb/issues/42426) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB server cannot start due to an error in reading the cgroup information with the error message "can't read file memory.stat from cgroup v1: open /sys/memory.stat no such file or directory" [#42659](https://github.com/pingcap/tidb/issues/42659) @[hawkingrei](https://github.com/hawkingrei) + - Fix the `Duplicate Key` issue that occurs when updating the partition key of a row on a partitioned table with a global index [#42312](https://github.com/pingcap/tidb/issues/42312) @[L-maple](https://github.com/L-maple) + - Fix the issue that the `Scan Worker Time By Phase` chart in the TTL monitoring panel does not display data [#42515](https://github.com/pingcap/tidb/issues/42515) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that some queries on partitioned tables with a global index return incorrect results [#41991](https://github.com/pingcap/tidb/issues/41991) [#42065](https://github.com/pingcap/tidb/issues/42065) @[L-maple](https://github.com/L-maple) + - Fix the issue of displaying some error logs during the process of reorganizing a partitioned table [#42180](https://github.com/pingcap/tidb/issues/42180) @[mjonss](https://github.com/mjonss) + - Fix the issue that the data length in the `QUERY` column of the `INFORMATION_SCHEMA.DDL_JOBS` table might exceed the column definition [#42440](https://github.com/pingcap/tidb/issues/42440) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `INFORMATION_SCHEMA.CLUSTER_HARDWARE` table might display incorrect values in containers [#42851](https://github.com/pingcap/tidb/issues/42851) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that an incorrect result is returned when you query a partitioned table using `ORDER BY` + `LIMIT` [#43158](https://github.com/pingcap/tidb/issues/43158) @[Defined2014](https://github.com/Defined2014) + - Fix the issue of multiple DDL tasks running simultaneously using the ingest method [#42903](https://github.com/pingcap/tidb/issues/42903) @[tangenta](https://github.com/tangenta) + - Fix the wrong value returned when querying a partitioned table using `Limit` [#24636](https://github.com/pingcap/tidb/issues/24636) + - Fix the issue of displaying the incorrect TiDB address in IPv6 environment [#43260](https://github.com/pingcap/tidb/issues/43260) @[nexustar](https://github.com/nexustar) + - Fix the issue of displaying incorrect values for system variables `tidb_enable_tiflash_read_for_write_stmt` and `tidb_enable_exchange_partition` [#43281](https://github.com/pingcap/tidb/issues/43281) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that when `tidb_scatter_region` is enabled, Region does not automatically split after a partition is truncated [#43174](https://github.com/pingcap/tidb/issues/43174) [#43028](https://github.com/pingcap/tidb/issues/43028) @[jiyfhust](https://github.com/jiyfhust) + - Add checks on the tables with generated columns and report errors for unsupported DDL operations on these columns [#38988](https://github.com/pingcap/tidb/issues/38988) [#24321](https://github.com/pingcap/tidb/issues/24321) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the error message is incorrect in certain type conversion errors [#41730](https://github.com/pingcap/tidb/issues/41730) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that after a TiDB node is normally shutdown, DDL tasks triggered on this node will be canceled [#43854](https://github.com/pingcap/tidb/issues/43854) @[zimulala](https://github.com/zimulala) + - Fix the issue that when the PD member address changes, allocating ID for the `AUTO_INCREMENT` column will be blocked for a long time [#42643](https://github.com/pingcap/tidb/issues/42643) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue of reporting the `GC lifetime is shorter than transaction duration` error during DDL execution [#40074](https://github.com/pingcap/tidb/issues/40074) @[tangenta](https://github.com/tangenta) + - Fix the issue that metadata locks unexpectedly block the DDL execution [#43755](https://github.com/pingcap/tidb/issues/43755) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the cluster cannot query some system views in IPv6 environment [#43286](https://github.com/pingcap/tidb/issues/43286) @[Defined2014](https://github.com/Defined2014) + - Fix the issue of not finding the partition during inner join in dynamic pruning mode [#43686](https://github.com/pingcap/tidb/issues/43686) @[mjonss](https://github.com/mjonss) + - Fix the issue that TiDB reports syntax errors when analyzing tables [#43392](https://github.com/pingcap/tidb/issues/43392) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiCDC might lose some row changes during table renaming [#43338](https://github.com/pingcap/tidb/issues/43338) @[tangenta](https://github.com/tangenta) + - Fix the issue that TiDB server crashes when the client uses cursor reads [#38116](https://github.com/pingcap/tidb/issues/38116) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `ADMIN SHOW DDL JOBS LIMIT` returns incorrect results [#42298](https://github.com/pingcap/tidb/issues/42298) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the TiDB panic issue that occurs when querying union views and temporary tables with `UNION` [#42563](https://github.com/pingcap/tidb/issues/42563) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that renaming tables does not take effect when committing multiple statements in a transaction [#39664](https://github.com/pingcap/tidb/issues/39664) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the incompatibility issue between the behavior of prepared plan cache and non-prepared plan cache during time conversion [#42439](https://github.com/pingcap/tidb/issues/42439) @[qw4990](https://github.com/qw4990) + - Fix the wrong results caused by plan cache for Decimal type [#43311](https://github.com/pingcap/tidb/issues/43311) @[qw4990](https://github.com/qw4990) + - Fix the TiDB panic issue in null-aware anti join (NAAJ) due to the wrong field type check [#42459](https://github.com/pingcap/tidb/issues/42459) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that DML execution failures in pessimistic transactions at the RC isolation level might cause inconsistency between data and indexes [#43294](https://github.com/pingcap/tidb/issues/43294) @[ekexium](https://github.com/ekexium) + - Fix the issue that in some extreme cases, when the first statement of a pessimistic transaction is retried, resolving locks on this transaction might affect transaction correctness [#42937](https://github.com/pingcap/tidb/issues/42937) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that in some rare cases, residual pessimistic locks of pessimistic transactions might affect data correctness when GC resolves locks [#43243](https://github.com/pingcap/tidb/issues/43243) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that the `LOCK` to `PUT` optimization leads to duplicate data being returned in specific queries [#28011](https://github.com/pingcap/tidb/issues/28011) @[zyguan](https://github.com/zyguan) + - Fix the issue that when data is changed, the locking behavior of the unique index is not consistent with that when the data is unchanged [#36438](https://github.com/pingcap/tidb/issues/36438) @[zyguan](https://github.com/zyguan) + ++ TiKV + + - Fix the issue that when you enable `tidb_pessimistic_txn_fair_locking`, in some extreme cases, expired requests caused by failed RPC retries might affect data correctness during the resolve lock operation [#14551](https://github.com/tikv/tikv/issues/14551) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that when you enable `tidb_pessimistic_txn_fair_locking`, in some extreme cases, expired requests caused by failed RPC retries might cause transaction conflicts to be ignored, thus affecting transaction consistency [#14311](https://github.com/tikv/tikv/issues/14311) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that encryption key ID conflict might cause the deletion of the old keys [#14585](https://github.com/tikv/tikv/issues/14585) @[tabokie](https://github.com/tabokie) + - Fix the performance degradation issue caused by accumulated lock records when a cluster is upgraded from a previous version to v6.5 or later versions [#14780](https://github.com/tikv/tikv/issues/14780) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that the `raft entry is too large` error occurs during the PITR recovery process [#14313](https://github.com/tikv/tikv/issues/14313) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV panics during the PITR recovery process due to `log_batch` exceeding 2 GB [#13848](https://github.com/tikv/tikv/issues/13848) @[YuJuncen](https://github.com/YuJuncen) + ++ PD + + - Fix the issue that the number of `low space store` in the PD monitoring panel is abnormal after TiKV panics [#6252](https://github.com/tikv/pd/issues/6252) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that Region Health monitoring data is deleted after PD leader switch [#6366](https://github.com/tikv/pd/issues/6366) @[iosmanthus](https://github.com/iosmanthus) + - Fix the issue that the rule checker cannot repair unhealthy Regions with the `schedule=deny` label [#6426](https://github.com/tikv/pd/issues/6426) @[nolouch](https://github.com/nolouch) + - Fix the issue that some existing labels are lost after TiKV or TiFlash restarts [#6467](https://github.com/tikv/pd/issues/6467) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the replication status cannot be switched when there are learner nodes in the replication mode [#14704](https://github.com/tikv/tikv/issues/14704) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Fix the issue that querying data in the `TIMESTAMP` or `TIME` type returns errors after enabling late materialization [#7455](https://github.com/pingcap/tiflash/issues/7455) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that large update transactions might cause TiFlash to repeatedly report errors and restart [#7316](https://github.com/pingcap/tiflash/issues/7316) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue of backup slowdown when a TiKV node crashes in a cluster [#42973](https://github.com/pingcap/tidb/issues/42973) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue of inaccurate error messages caused by a backup failure in some cases [#43236](https://github.com/pingcap/tidb/issues/43236) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the issue of TiCDC time zone setting [#8798](https://github.com/pingcap/tiflow/issues/8798) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiCDC cannot automatically recover when PD address or leader fails [#8812](https://github.com/pingcap/tiflow/issues/8812) [#8877](https://github.com/pingcap/tiflow/issues/8877) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that checkpoint lag increases when one of the upstream TiKV nodes crashes [#8858](https://github.com/pingcap/tiflow/issues/8858) @[hicqu](https://github.com/hicqu) + - Fix the issue that when replicating data to object storage, the `EXCHANGE PARTITION` operation in the upstream cannot be properly replicated to the downstream [#8914](https://github.com/pingcap/tiflow/issues/8914) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the OOM issue caused by excessive memory usage of the sorter component in some special scenarios [#8974](https://github.com/pingcap/tiflow/issues/8974) @[hicqu](https://github.com/hicqu) + - Fix the TiCDC node panic that occurs when the downstream Kafka sinks are rolling restarted [#9023](https://github.com/pingcap/tiflow/issues/9023) @[asddongmen](https://github.com/asddongmen) + + + TiDB Data Migration (DM) + + - Fix the issue that latin1 data might be corrupted during replication [#7028](https://github.com/pingcap/tiflow/issues/7028) @[lance6716](https://github.com/lance6716) + + + TiDB Dumpling + + - Fix the issue that the `UNSIGNED INTEGER` type primary key cannot be used for splitting chunks [#42620](https://github.com/pingcap/tidb/issues/42620) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that TiDB Dumpling might panic when `--output-file-template` is incorrectly set [#42391](https://github.com/pingcap/tidb/issues/42391) @[lichunzhu](https://github.com/lichunzhu) + + + TiDB Binlog + + - Fix the issue that an error might occur when encountering a failed DDL statement [#1228](https://github.com/pingcap/tidb-binlog/issues/1228) @[okJiang](https://github.com/okJiang) + + + TiDB Lightning + + - Fix the performance degradation issue during data import [#42456](https://github.com/pingcap/tidb/issues/42456) @[lance6716](https://github.com/lance6716) + - Fix the issue of `write to tikv with no leader returned` when importing a large amount of data [#43055](https://github.com/pingcap/tidb/issues/43055) @[lance6716](https://github.com/lance6716) + - Fix the issue of excessive `keys within region is empty, skip doIngest` logs during data import [#43197](https://github.com/pingcap/tidb/issues/43197) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that panic might occur during partial write [#43363](https://github.com/pingcap/tidb/issues/43363) @[lance6716](https://github.com/lance6716) + - Fix the issue that OOM might occur when importing a wide table [#43728](https://github.com/pingcap/tidb/issues/43728) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue of missing data in the TiDB Lightning Grafana dashboard [#43357](https://github.com/pingcap/tidb/issues/43357) @[lichunzhu](https://github.com/lichunzhu) + - Fix the import failure due to incorrect setting of `keyspace-name` [#43684](https://github.com/pingcap/tidb/issues/43684) @[zeminzhou](https://github.com/zeminzhou) + - Fix the issue that data import might be skipped during range partial write in some cases [#43768](https://github.com/pingcap/tidb/issues/43768) @[lance6716](https://github.com/lance6716) + +## Performance test + +To learn about the performance of TiDB v7.1.0, you can refer to the [TPC-C performance test report](https://docs.pingcap.com/tidbcloud/v7.1.0-performance-benchmarking-with-tpcc) and [Sysbench performance test report](https://docs.pingcap.com/tidbcloud/v7.1.0-performance-benchmarking-with-sysbench) of the TiDB Dedicated cluster. + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [blacktear23](https://github.com/blacktear23) +- [ethercflow](https://github.com/ethercflow) +- [hihihuhu](https://github.com/hihihuhu) +- [jiyfhust](https://github.com/jiyfhust) +- [L-maple](https://github.com/L-maple) +- [lqs](https://github.com/lqs) +- [pingandb](https://github.com/pingandb) +- [yorkhellen](https://github.com/yorkhellen) +- [yujiarista](https://github.com/yujiarista) (First-time contributor) diff --git a/releases/release-7.1.1.md b/releases/release-7.1.1.md new file mode 100644 index 0000000000000..cd905ea59ef0c --- /dev/null +++ b/releases/release-7.1.1.md @@ -0,0 +1,157 @@ +--- +title: TiDB 7.1.1 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.1.1. +--- + +# TiDB 7.1.1 Release Notes + +Release date: July 24, 2023 + +TiDB version: 7.1.1 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.1/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.1/production-deployment-using-tiup) + +## Compatibility changes + +- TiDB introduces a new system variable `tidb_lock_unchanged_keys` to control whether to lock unchanged keys [#44714](https://github.com/pingcap/tidb/issues/44714) @[ekexium](https://github.com/ekexium) + +### Behavior changes + +- When processing update event, TiCDC splits an event into delete and insert events if the primary key or non-null unique index value is modified in the event. For more information, see [documentation](/ticdc/ticdc-split-update-behavior.md#transactions-containing-a-single-update-change). + +## Improvements + ++ TiDB + + - Plan Cache supports queries with more than 200 parameters [#44823](https://github.com/pingcap/tidb/issues/44823) @[qw4990](https://github.com/qw4990) + - Optimize the performance of reading the dumped chunks from disk [#45125](https://github.com/pingcap/tidb/issues/45125) @[YangKeao](https://github.com/YangKeao) + - Optimize the logic of constructing index scan range so that it supports converting complex conditions into index scan range [#41572](https://github.com/pingcap/tidb/issues/41572) [#44389](https://github.com/pingcap/tidb/issues/44389) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - When the retry leader of stale read encounters a lock, TiDB forcibly retries with the leader after resolving the lock, which avoids unnecessary overhead [#43659](https://github.com/pingcap/tidb/issues/43659) @[you06](https://github.com/you06) + ++ PD + + - PD blocks Swagger API by default when the Swagger server is disabled [#6786](https://github.com/tikv/pd/issues/6786) @[bufferflies](https://github.com/bufferflies) + ++ Tools + + + TiCDC + + - Optimize the encoding format of binary fields when TiCDC replicates data to object storage services [#9373](https://github.com/pingcap/tiflow/issues/9373) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support the OAUTHBEARER authentication in the scenario of replication to Kafka [#8865](https://github.com/pingcap/tiflow/issues/8865) @[hi-rustin](https://github.com/Rustin170506) + + + TiDB Lightning + + - Improve the retry logic of TiDB Lightning for the PD `ClientTSOStreamClosed` error during the checksum phase [#45301](https://github.com/pingcap/tidb/issues/45301) @[lance6716](https://github.com/lance6716) + - Verify checksum through SQL after the import to improve stability of verification [#41941](https://github.com/pingcap/tidb/issues/41941) @[GMHDBJD](https://github.com/GMHDBJD) + + + Dumpling + + - Dumpling avoids executing table queries when the `--sql` parameter is used, thereby reducing the export overhead [#45239](https://github.com/pingcap/tidb/issues/45239) @[lance6716](https://github.com/lance6716) + + + TiDB Binlog + + - Optimize the method of retrieving table information to reduce the initialization time and memory usage of Drainer [#1137](https://github.com/pingcap/tidb-binlog/issues/1137) @[lichunzhu](https://github.com/lichunzhu) + +## Bug fixes + ++ TiDB + + - Fix the issue that the GC Resolve Locks step might miss some pessimistic locks [#45134](https://github.com/pingcap/tidb/issues/45134) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that Stats Collector might cause deadlock when a new session is created [#44502](https://github.com/pingcap/tidb/issues/44502) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Fix the potential memory leak issue in memory tracker [#44612](https://github.com/pingcap/tidb/issues/44612) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that batch coprocessor retry might generate incorrect Region information that causes query failure [#44622](https://github.com/pingcap/tidb/issues/44622) @[windtalker](https://github.com/windtalker) + - Fix the potential data race issue in index scan [#45126](https://github.com/pingcap/tidb/issues/45126) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that query results in MPP mode are incorrect when `tidb_enable_parallel_apply` is enabled [#45299](https://github.com/pingcap/tidb/issues/45299) @[windtalker](https://github.com/windtalker) + - Fix the hang-up issue that occurs when queries with `indexMerge` are killed [#45279](https://github.com/pingcap/tidb/issues/45279) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that excessive memory consumption of SQL execution details in statistics causes TiDB OOM in extreme cases [#44047](https://github.com/pingcap/tidb/issues/44047) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `FormatSQL()` method cannot properly truncate extremely long SQL statements in input [#44542](https://github.com/pingcap/tidb/issues/44542) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that DDL operations get stuck during cluster upgrade, which causes upgrade failure [#44158](https://github.com/pingcap/tidb/issues/44158) @[zimulala](https://github.com/zimulala) + - Fix the issue that other TiDB nodes do not take over TTL tasks after failures in one TiDB node [#45022](https://github.com/pingcap/tidb/issues/45022) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that when the MySQL Cursor Fetch protocol is used, the memory consumption of result sets might exceed the `tidb_mem_quota_query` limit and causes TiDB OOM. After the fix, TiDB will automatically write result sets to the disk to release memory [#43233](https://github.com/pingcap/tidb/issues/43233) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that users can view information in the `INFORMATION_SCHEMA.TIFLASH_REPLICA` table even without permissions [#45320](https://github.com/pingcap/tidb/issues/45320) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that `ROW_COUNT` returned by the `ADMIN SHOW DDL JOBS` statement is inaccurate [#44044](https://github.com/pingcap/tidb/issues/44044) @[tangenta](https://github.com/tangenta) + - Fix the issue that querying a Range COLUMNS partitioned table might get an error [#43459](https://github.com/pingcap/tidb/issues/43459) @[mjonss](https://github.com/mjonss) + - Fix the issue that resuming a paused DDL task fails [#44217](https://github.com/pingcap/tidb/issues/44217) @[dhysum](https://github.com/dhysum) + - Fix the issue that in-memory pessimistic locks cause `FLASHBACK` failures and data inconsistency [#44292](https://github.com/pingcap/tidb/issues/44292) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that deleted tables can still be read from `INFORMATION_SCHEMA` [#43714](https://github.com/pingcap/tidb/issues/43714) @[tangenta](https://github.com/tangenta) + - Fix the issue that the cluster upgrade fails when there are paused DDL operations before the upgrade [#44225](https://github.com/pingcap/tidb/issues/44225) @[zimulala](https://github.com/zimulala) + - Fix the `duplicate entry` error that occurs when restoring a table with `AUTO_ID_CACHE=1` using BR [#44716](https://github.com/pingcap/tidb/issues/44716) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the data index inconsistency issue triggered by multiple switches of DDL owner [#44619](https://github.com/pingcap/tidb/issues/44619) @[tangenta](https://github.com/tangenta) + - Fix the issue that canceling an `ADD INDEX` DDL task in the `none` status might cause memory leak because this task is not removed from the Distributed eXecution Framework (DXF) task queue [#44205](https://github.com/pingcap/tidb/issues/44205) @[tangenta](https://github.com/tangenta) + - Fix the issue that the proxy protocol reports the `Header read timeout` error when processing certain erroneous data [#43205](https://github.com/pingcap/tidb/issues/43205) @[blacktear23](https://github.com/blacktear23) + - Fix the issue that PD isolation might block the running DDL [#44267](https://github.com/pingcap/tidb/issues/44267) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the query result of the `SELECT CAST(n AS CHAR)` statement is incorrect when `n` in the statement is a negative number [#44786](https://github.com/pingcap/tidb/issues/44786) @[xhebox](https://github.com/xhebox) + - Fix the issue of excessive memory usage after creating a large number of empty partitioned tables [#44308](https://github.com/pingcap/tidb/issues/44308) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that Join Reorder might cause incorrect outer join results [#44314](https://github.com/pingcap/tidb/issues/44314) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that queries containing Common Table Expressions (CTEs) might cause insufficient disk space [#44477](https://github.com/pingcap/tidb/issues/44477) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that dropping a database causes slow GC progress [#33069](https://github.com/pingcap/tidb/issues/33069) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that adding an index fails in the ingest mode [#44137](https://github.com/pingcap/tidb/issues/44137) @[tangenta](https://github.com/tangenta) + - Fix the issue that the `SELECT` statement returns an error for a partitioned table if the table partition definition uses the `FLOOR()` function to round a partitioned column [#42323](https://github.com/pingcap/tidb/issues/42323) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that follower read does not handle flashback errors before retrying, which causes query errors [#43673](https://github.com/pingcap/tidb/issues/43673) @[you06](https://github.com/you06) + - Fix the issue that using `memTracker` with cursor fetch causes memory leaks [#44254](https://github.com/pingcap/tidb/issues/44254) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the `SHOW PROCESSLIST` statement cannot display the TxnStart of the transaction of the statement with a long subquery time [#40851](https://github.com/pingcap/tidb/issues/40851) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the `LEADING` hint does not support querying block aliases [#44645](https://github.com/pingcap/tidb/issues/44645) @[qw4990](https://github.com/qw4990) + - Fix the issue that `PREPARE stmt FROM "ANALYZE TABLE xxx"` might be killed by `tidb_mem_quota_query` [#44320](https://github.com/pingcap/tidb/issues/44320) @[chrysan](https://github.com/chrysan) + - Fix the panic issue caused by empty `processInfo` [#43829](https://github.com/pingcap/tidb/issues/43829) @[zimulala](https://github.com/zimulala) + - Fix the issue that data and indexes are inconsistent when the `ON UPDATE` statement does not correctly update the primary key [#44565](https://github.com/pingcap/tidb/issues/44565) @[zyguan](https://github.com/zyguan) + - Fix the issue that queries might return incorrect results when `tidb_opt_agg_push_down` is enabled [#44795](https://github.com/pingcap/tidb/issues/44795) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that using CTEs and correlated subqueries simultaneously might result in incorrect query results or panic [#44649](https://github.com/pingcap/tidb/issues/44649) [#38170](https://github.com/pingcap/tidb/issues/38170) [#44774](https://github.com/pingcap/tidb/issues/44774) @[winoros](https://github.com/winoros) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that canceling a DDL task in the rollback state causes errors in related metadata [#44143](https://github.com/pingcap/tidb/issues/44143) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that executing the `UPDATE` statement causes errors due to checking foreign key constraints [#44848](https://github.com/pingcap/tidb/issues/44848) @[crazycs520](https://github.com/crazycs520) + ++ PD + + - Fix the issue that Resource Manager repeatedly initializes the default resource group [#6787](https://github.com/tikv/pd/issues/6787) @[glorv](https://github.com/glorv) + - Fix the issue that in some cases, the `location-labels` set in the Placement Rules in SQL does not schedule as expected [#6662](https://github.com/tikv/pd/issues/6662) @[rleungx](https://github.com/rleungx) + - Fix the issue that redundant replicas cannot be automatically repaired in some corner cases [#6573](https://github.com/tikv/pd/issues/6573) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Fix the issue that in the disaggregated storage and compute architecture mode, the TiFlash compute node fetches inaccurate CPU core information [#7436](https://github.com/pingcap/tiflash/issues/7436) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiFlash takes too long to restart after using Online Unsafe Recovery [#7671](https://github.com/pingcap/tiflash/issues/7671) @[hongyunyan](https://github.com/hongyunyan) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that `checksum mismatch` is falsely reported in some cases [#44472](https://github.com/pingcap/tidb/issues/44472) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the frequency of `resolve lock` is too high when there is no PITR backup task in the TiDB cluster [#40759](https://github.com/pingcap/tidb/issues/40759) @[joccau](https://github.com/joccau) + + + TiCDC + + - Fix the issue that a PD exception might cause the replication task to get stuck [#8808](https://github.com/pingcap/tiflow/issues/8808) [#9054](https://github.com/pingcap/tiflow/issues/9054) @[asddongmen](https://github.com/asddongmen) @[fubinzh](https://github.com/fubinzh) + - Fix the issue of excessive memory consumption when replicating to an object storage service [#8894](https://github.com/pingcap/tiflow/issues/8894) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the replication task might get stuck when the redo log is enabled and there is an exception downstream [#9172](https://github.com/pingcap/tiflow/issues/9172) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that TiCDC keeps retrying when there is a downstream failure, which causes the retry time to be too long [#9272](https://github.com/pingcap/tiflow/issues/9272) @[asddongmen](https://github.com/asddongmen) + - Fix the issue of excessive downstream pressure caused by reading downstream metadata too frequently when replicating data to Kafka [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that when the downstream is Kafka, TiCDC queries the downstream metadata too frequently and causes excessive workload in the downstream [#8957](https://github.com/pingcap/tiflow/issues/8957) [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/Rustin170506) + - Fix the OOM issue caused by excessive memory usage of the sorter component in some special scenarios [#8974](https://github.com/pingcap/tiflow/issues/8974) @[hicqu](https://github.com/hicqu) + - Fix the issue that the `UPDATE` operation cannot output old values when the Avro or CSV protocol is used [#9086](https://github.com/pingcap/tiflow/issues/9086) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that when replicating data to storage services, the JSON file corresponding to downstream DDL statements does not record the default values of table fields [#9066](https://github.com/pingcap/tiflow/issues/9066) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue of too many downstream logs caused by frequently setting the downstream bidirectional replication-related variables when replicating data to TiDB or MySQL [#9180](https://github.com/pingcap/tiflow/issues/9180) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that when a replication error occurs due to an oversized Kafka message, the message body is recorded in the log [#9031](https://github.com/pingcap/tiflow/issues/9031) @[darraes](https://github.com/darraes) + - Fix the issue that TiCDC gets stuck when PD fails such as network isolation or PD Owner node reboot [#8808](https://github.com/pingcap/tiflow/issues/8808) [#8812](https://github.com/pingcap/tiflow/issues/8812) [#8877](https://github.com/pingcap/tiflow/issues/8877) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that Avro protocol incorrectly identifies `Enum` type values [#9259](https://github.com/pingcap/tiflow/issues/9259) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Fix the issue that DM-master exits abnormally when a unique index contains empty columns in the table to be migrated [#9247](https://github.com/pingcap/tiflow/issues/9247) @[lance6716](https://github.com/lance6716) + + + TiDB Lightning + + - Fix the issue that the failed connection between TiDB Lightning and PD cannot be retried, improving the import success rate [#43400](https://github.com/pingcap/tidb/issues/43400) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that TiDB Lightning does not correctly display the error message when writing data to TiKV returns an out of space error [#44733](https://github.com/pingcap/tidb/issues/44733) @[lance6716](https://github.com/lance6716) + - Fix the issue that the `Region is unavailable` error is reported during checksum operation [#45462](https://github.com/pingcap/tidb/issues/45462) @[D3Hunter](https://github.com/D3Hunter) + - Fix the TiDB Lightning panic issue when `experimental.allow-expression-index` is enabled and the default value is UUID [#44497](https://github.com/pingcap/tidb/issues/44497) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that disk quota might be inaccurate due to competing conditions [#44867](https://github.com/pingcap/tidb/issues/44867) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that in Logical Import Mode, deleting tables downstream during import might cause TiDB Lightning metadata not to be updated in time [#44614](https://github.com/pingcap/tidb/issues/44614) @[dsdashun](https://github.com/dsdashun) + + + Dumpling + + - Fix the issue that Dumpling exits abnormally when the query result set of `--sql` is empty [#45200](https://github.com/pingcap/tidb/issues/45200) @[D3Hunter](https://github.com/D3Hunter) + + + TiDB Binlog + + - Fix the issue that TiDB cannot correctly query Binlog node status via `SHOW PUMP STATUS` or `SHOW DRAINER STATUS` after a complete change of the PD address [#42643](https://github.com/pingcap/tidb/issues/42643) @[lichunzhu](https://github.com/lichunzhu) + - Fix the issue that TiDB cannot write binlogs after a complete change of the PD address [#42643](https://github.com/pingcap/tidb/issues/42643) @[lance6716](https://github.com/lance6716) + - Fix the issue that the etcd client does not automatically synchronize the latest node information during initialization [#1236](https://github.com/pingcap/tidb-binlog/issues/1236) @[lichunzhu](https://github.com/lichunzhu) diff --git a/releases/release-7.1.3.md b/releases/release-7.1.3.md new file mode 100644 index 0000000000000..cabdb83df6bc1 --- /dev/null +++ b/releases/release-7.1.3.md @@ -0,0 +1,162 @@ +--- +title: TiDB 7.1.3 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.1.3. +--- + +# TiDB 7.1.3 Release Notes + +Release date: December 21, 2023 + +TiDB version: 7.1.3 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.1/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.1/production-deployment-using-tiup) + +## Compatibility changes + +- After further testing, the default value of the TiCDC Changefeed configuration item [`case-sensitive`](/ticdc/ticdc-changefeed-config.md) is changed from `true` to `false`. This means that by default, table and database names in the TiCDC configuration file are case-insensitive [#10047](https://github.com/pingcap/tiflow/issues/10047) @[sdojjy](https://github.com/sdojjy) +- TiCDC Changefeed introduces the following new configuration items: + - [`sql-mode`](/ticdc/ticdc-changefeed-config.md): enables you to set the [SQL mode](https://docs.pingcap.com/tidb/v7.1/ticdc-ddl#sql-mode) used by TiCDC to parse DDL statements when TiCDC replicates data [#9876](https://github.com/pingcap/tiflow/issues/9876) @[asddongmen](https://github.com/asddongmen) + - [`encoding-worker-num`](/ticdc/ticdc-changefeed-config.md) and [`flush-worker-num`](/ticdc/ticdc-changefeed-config.md): enables you to set different concurrency parameters for the redo module based on specifications of different machines [#10048](https://github.com/pingcap/tiflow/issues/10048) @[CharlesCheung96](https://github.com/CharlesCheung96) + - [`compression`](/ticdc/ticdc-changefeed-config.md): enables you to configure the compression behavior of redo log files [#10176](https://github.com/pingcap/tiflow/issues/10176) @[sdojjy](https://github.com/sdojjy) + - [`sink.cloud-storage-config`](/ticdc/ticdc-changefeed-config.md): enables you to set the automatic cleanup of historical data when replicating data to object storage [#10109](https://github.com/pingcap/tiflow/issues/10109) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Improvements + ++ TiDB + + - Support the [`FLASHBACK CLUSTER TO TSO`](https://docs.pingcap.com/tidb/v7.1/sql-statement-flashback-cluster) syntax [#48372](https://github.com/pingcap/tidb/issues/48372) @[BornChanger](https://github.com/BornChanger) + ++ PD + + - Enhance the configuration retrieval method of the resource control client to dynamically fetch the latest configurations [#7043](https://github.com/tikv/pd/issues/7043) @[nolouch](https://github.com/nolouch) + ++ Tools + + + Backup & Restore (BR) + + - Enable automatic retry of Region scatter during snapshot recovery when encountering timeout failures or cancellations of Region scatter [#47236](https://github.com/pingcap/tidb/issues/47236) @[Leavrth](https://github.com/Leavrth) + - During restoring a snapshot backup, BR retries when it encounters certain network errors [#48528](https://github.com/pingcap/tidb/issues/48528) @[Leavrth](https://github.com/Leavrth) + - Introduce a new integration test for Point-In-Time Recovery (PITR) in the `delete range` scenario, enhancing PITR stability [#47738](https://github.com/pingcap/tidb/issues/47738) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Optimize the memory consumption when TiCDC nodes replicate data to TiDB [#9935](https://github.com/pingcap/tiflow/issues/9935) @[3AceShowHand](https://github.com/3AceShowHand) + - Optimize some alarm rules [#9266](https://github.com/pingcap/tiflow/issues/9266) @[asddongmen](https://github.com/asddongmen) + - Optimize the performance of redo log, including parallel writing data to S3 and adopting lz4 compression algorithm [#10176](https://github.com/pingcap/tiflow/issues/10176) [#10226](https://github.com/pingcap/tiflow/issues/10226) @[sdojjy](https://github.com/sdojjy) + - Improve the performance of TiCDC replicating data to object storage by increasing parallelism [#10098](https://github.com/pingcap/tiflow/issues/10098) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Reduce the impact of TiCDC incremental scanning on upstream TiKV [#11390](https://github.com/tikv/tikv/issues/11390) @[hicqu](https://github.com/hicqu) + - Support making TiCDC Canal-JSON content format [compatible with the content format of the official Canal output](https://docs.pingcap.com/tidb/v6.5/ticdc-canal-json#compatibility-with-the-official-canal) by setting `content-compatible=true` in the `sink-uri` configuration [#10106](https://github.com/pingcap/tiflow/issues/10106) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Lightning + + - Add a retry mechanism for `GetTS` failure caused by PD leader change [#45301](https://github.com/pingcap/tidb/issues/45301) @[lance6716](https://github.com/lance6716) + +## Bug fixes + ++ TiDB + + - Fix the issue that queries containing common table expressions (CTEs) unexpectedly get stuck when the memory limit is exceeded [#49096](https://github.com/pingcap/tidb/issues/49096) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that high CPU usage of TiDB occurs due to long-term memory pressure caused by `tidb_server_memory_limit` [#48741](https://github.com/pingcap/tidb/issues/48741) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that queries containing CTEs report `runtime error: index out of range [32] with length 32` when `tidb_max_chunk_size` is set to a small value [#48808](https://github.com/pingcap/tidb/issues/48808) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the query result is incorrect when an `ENUM` type column is used as the join key [#48991](https://github.com/pingcap/tidb/issues/48991) @[winoros](https://github.com/winoros) + - Fix the parsing error caused by aggregate or window functions in recursive CTEs [#47711](https://github.com/pingcap/tidb/issues/47711) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that `UPDATE` statements might be incorrectly converted to PointGet [#47445](https://github.com/pingcap/tidb/issues/47445) @[hi-rustin](https://github.com/Rustin170506) + - Fix the OOM issue that might occur when TiDB performs garbage collection on the `stats_history` table [#48431](https://github.com/pingcap/tidb/issues/48431) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the same query plan has different `PLAN_DIGEST` values in some cases [#47634](https://github.com/pingcap/tidb/issues/47634) @[King-Dylan](https://github.com/King-Dylan) + - Fix the issue that `GenJSONTableFromStats` cannot be killed when it consumes a large amount of memory [#47779](https://github.com/pingcap/tidb/issues/47779) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the result might be incorrect when predicates are pushed down to common table expressions [#47881](https://github.com/pingcap/tidb/issues/47881) @[winoros](https://github.com/winoros) + - Fix the issue that `Duplicate entry` might occur when `AUTO_ID_CACHE=1` is set [#46444](https://github.com/pingcap/tidb/issues/46444) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB server might consume a significant amount of resources when the enterprise plugin for audit logging is used [#49273](https://github.com/pingcap/tidb/issues/49273) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that TiDB server might panic during graceful shutdown [#36793](https://github.com/pingcap/tidb/issues/36793) @[bb7133](https://github.com/bb7133) + - Fix the issue that tables with `AUTO_ID_CACHE=1` might lead to gRPC client leaks when there are a large number of tables [#48869](https://github.com/pingcap/tidb/issues/48869) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the incorrect error message for `ErrLoadDataInvalidURI` (invalid S3 URI error) [#48164](https://github.com/pingcap/tidb/issues/48164) @[lance6716](https://github.com/lance6716) + - Fix the issue that executing `ALTER TABLE ... LAST PARTITION` fails when the partition column type is `DATETIME` [#48814](https://github.com/pingcap/tidb/issues/48814) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the actual error message during `IMPORT INTO` execution might be overridden by other error messages [#47992](https://github.com/pingcap/tidb/issues/47992) [#47781](https://github.com/pingcap/tidb/issues/47781) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that TiDB deployed in the cgroup v2 container cannot be detected [#48342](https://github.com/pingcap/tidb/issues/48342) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that executing `UNION ALL` with the DUAL table as the first subnode might cause an error [#48755](https://github.com/pingcap/tidb/issues/48755) @[winoros](https://github.com/winoros) + - Fix the TiDB node panic issue that occurs when DDL `jobID` is restored to 0 [#46296](https://github.com/pingcap/tidb/issues/46296) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue of unsorted row data returned by `TABLESAMPLE` [#48253](https://github.com/pingcap/tidb/issues/48253) @[tangenta](https://github.com/tangenta) + - Fix the issue that panic might occur when `tidb_enable_ordered_result_mode` is enabled [#45044](https://github.com/pingcap/tidb/issues/45044) @[qw4990](https://github.com/qw4990) + - Fix the issue that the optimizer mistakenly selects IndexFullScan to reduce sort introduced by window functions [#46177](https://github.com/pingcap/tidb/issues/46177) @[qw4990](https://github.com/qw4990) + - Fix the issue of not handling locks in the MVCC interface when reading schema diff commit versions from the TiDB schema cache [#48281](https://github.com/pingcap/tidb/issues/48281) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue of incorrect memory usage estimation in `INDEX_LOOKUP_HASH_JOIN` [#47788](https://github.com/pingcap/tidb/issues/47788) @[SeaRise](https://github.com/SeaRise) + - Fix the issue of `IMPORT INTO` task failure caused by PD leader malfunction for 1 minute [#48307](https://github.com/pingcap/tidb/issues/48307) @[D3Hunter](https://github.com/D3Hunter) + - Fix the panic issue of `batch-client` in `client-go` [#47691](https://github.com/pingcap/tidb/issues/47691) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that column pruning can cause panic in specific situations [#47331](https://github.com/pingcap/tidb/issues/47331) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiDB does not read `cgroup` resource limits when it is started with `systemd` [#47442](https://github.com/pingcap/tidb/issues/47442) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue of possible syntax error when a common table expression (CTE) containing aggregate or window functions is referenced by other recursive CTEs [#47603](https://github.com/pingcap/tidb/issues/47603) [#47711](https://github.com/pingcap/tidb/issues/47711) @[elsa0520](https://github.com/elsa0520) + - Fix the panic issue that might occur when constructing TopN structure for statistics [#35948](https://github.com/pingcap/tidb/issues/35948) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the result of `COUNT(INT)` calculated by MPP might be incorrect [#48643](https://github.com/pingcap/tidb/issues/48643) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the chunk cannot be reused when the HashJoin operator performs probe [#48082](https://github.com/pingcap/tidb/issues/48082) @[wshwsh12](https://github.com/wshwsh12) + ++ TiKV + + - Fix the issue that if TiKV runs extremely slowly, it might panic after Region merge [#16111](https://github.com/tikv/tikv/issues/16111) @[overvenus](https://github.com/overvenus) + - Fix the issue that Resolved TS might be blocked for two hours [#15520](https://github.com/tikv/tikv/issues/15520) [#39130](https://github.com/pingcap/tidb/issues/39130) @[overvenus](https://github.com/overvenus) + - Fix the issue that TiKV reports the `ServerIsBusy` error because it can not append the raft log [#15800](https://github.com/tikv/tikv/issues/15800) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that snapshot restore might get stuck when BR crashes [#15684](https://github.com/tikv/tikv/issues/15684) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that Resolved TS in stale read might cause TiKV OOM issues when tracking large transactions [#14864](https://github.com/tikv/tikv/issues/14864) @[overvenus](https://github.com/overvenus) + - Fix the issue that damaged SST files might be spread to other TiKV nodes [#15986](https://github.com/tikv/tikv/issues/15986) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the joint state of DR Auto-Sync might time out when scaling out [#15817](https://github.com/tikv/tikv/issues/15817) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the scheduler command variables are incorrect in Grafana on the cloud environment [#15832](https://github.com/tikv/tikv/issues/15832) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that stale peers are retained and block resolved-ts after Regions are merged [#15919](https://github.com/tikv/tikv/issues/15919) @[overvenus](https://github.com/overvenus) + - Fix the issue that Online Unsafe Recovery cannot handle merge abort [#15580](https://github.com/tikv/tikv/issues/15580) @[v01dstar](https://github.com/v01dstar) + - Fix the TiKV OOM issue that occurs when restarting TiKV and there are a large number of Raft logs that are not applied [#15770](https://github.com/tikv/tikv/issues/15770) @[overvenus](https://github.com/overvenus) + - Fix security issues by upgrading the version of `lz4-sys` to 1.9.4 [#15621](https://github.com/tikv/tikv/issues/15621) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + - Fix the issue that `blob-run-mode` in Titan cannot be updated online [#15978](https://github.com/tikv/tikv/issues/15978) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that network interruption between PD and TiKV might cause PITR to get stuck [#15279](https://github.com/tikv/tikv/issues/15279) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV coprocessor might return stale data when removing a Raft peer [#16069](https://github.com/tikv/tikv/issues/16069) @[overvenus](https://github.com/overvenus) + ++ PD + + - Fix the issue that the `resource_manager_resource_unit` metric is empty in TiDB Dashboard when executing `CALIBRATE RESOURCE` [#45166](https://github.com/pingcap/tidb/issues/45166) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that the Calibrate by Workload page reports an error [#48162](https://github.com/pingcap/tidb/issues/48162) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that deleting a resource group can damage DDL atomicity [#45050](https://github.com/pingcap/tidb/issues/45050) @[glorv](https://github.com/glorv) + - Fix the issue that when PD leader is transferred and there is a network partition between the new leader and the PD client, the PD client fails to update the information of the leader [#7416](https://github.com/tikv/pd/issues/7416) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that adding multiple TiKV nodes to a large cluster might cause TiKV heartbeat reporting to become slow or stuck [#7248](https://github.com/tikv/pd/issues/7248) @[rleungx](https://github.com/rleungx) + - Fix the issue that TiDB Dashboard cannot read PD `trace` data correctly [#7253](https://github.com/tikv/pd/issues/7253) @[nolouch](https://github.com/nolouch) + - Fix some security issues by upgrading the version of Gin Web Framework from v1.8.1 to v1.9.1 [#7438](https://github.com/tikv/pd/issues/7438) @[niubell](https://github.com/niubell) + - Fix the issue that the rule checker does not add Learners according to the configuration of Placement Rules [#7185](https://github.com/tikv/pd/issues/7185) @[nolouch](https://github.com/nolouch) + - Fix the issue that PD might delete normal Peers when TiKV nodes are unavailable [#7249](https://github.com/tikv/pd/issues/7249) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that it takes a long time to switch the leader in DR Auto-Sync mode [#6988](https://github.com/tikv/pd/issues/6988) @[HuSharp](https://github.com/HuSharp) + ++ TiFlash + + - Fix the issue that executing the `ALTER TABLE ... EXCHANGE PARTITION ...` statement causes panic [#8372](https://github.com/pingcap/tiflash/issues/8372) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue of memory leak when TiFlash encounters memory limitation during query [#8447](https://github.com/pingcap/tiflash/issues/8447) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that data of TiFlash replicas would still be garbage collected after executing `FLASHBACK DATABASE` [#8450](https://github.com/pingcap/tiflash/issues/8450) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix incorrect display of maximum percentile time for some panels in Grafana [#8076](https://github.com/pingcap/tiflash/issues/8076) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that a query returns the unexpected error message "Block schema mismatch in FineGrainedShuffleWriter-V1" [#8111](https://github.com/pingcap/tiflash/issues/8111) @[SeaRise](https://github.com/SeaRise) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the default values for BR SQL commands and CLI are different, which might cause OOM issues [#48000](https://github.com/pingcap/tidb/issues/48000) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the log backup might get stuck in some scenarios when backing up large wide tables [#15714](https://github.com/tikv/tikv/issues/15714) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that BR generates incorrect URIs for external storage files [#48452](https://github.com/pingcap/tidb/issues/48452) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the retry after an EC2 metadata connection reset causes degraded backup and restore performance [#47650](https://github.com/pingcap/tidb/issues/47650) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the log backup task can start but does not work properly if failing to connect to PD during task initialization [#16056](https://github.com/tikv/tikv/issues/16056) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the issue that the `WHERE` clause does not use the primary key as a condition when replicating `DELETE` statements in certain scenarios [#9812](https://github.com/pingcap/tiflow/issues/9812) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that replication tasks get stuck in certain special scenarios when replicating data to object storage [#10041](https://github.com/pingcap/tiflow/issues/10041) [#10044](https://github.com/pingcap/tiflow/issues/10044) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that replication tasks get stuck in certain special scenarios after enabling sync-point and redo log [#10091](https://github.com/pingcap/tiflow/issues/10091) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that TiCDC mistakenly closes the connection with TiKV in certain special scenarios [#10239](https://github.com/pingcap/tiflow/issues/10239) @[hicqu](https://github.com/hicqu) + - Fix the issue that the changefeed cannot replicate DML events in bidirectional replication mode if the target table is dropped and then recreated in upstream [#10079](https://github.com/pingcap/tiflow/issues/10079) @[asddongmen](https://github.com/asddongmen) + - Fix the performance issue caused by accessing NFS directories when replicating data to an object store sink [#10041](https://github.com/pingcap/tiflow/issues/10041) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the TiCDC server might panic when replicating data to an object storage service [#10137](https://github.com/pingcap/tiflow/issues/10137) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that the interval between replicating DDL statements is too long when redo log is enabled [#9960](https://github.com/pingcap/tiflow/issues/9960) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that an owner node gets stuck due to NFS failure when the redo log is enabled [#9886](https://github.com/pingcap/tiflow/issues/9886) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Fix the issue that DM performance is degraded due to an inappropriate algorithm used for `CompareGTID` [#9676](https://github.com/pingcap/tiflow/issues/9676) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Fix the issue that data import fails due to the PD leader being killed or slow processing of PD requests [#46950](https://github.com/pingcap/tidb/issues/46950) [#48075](https://github.com/pingcap/tidb/issues/48075) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that TiDB Lightning gets stuck during `writeToTiKV` [#46321](https://github.com/pingcap/tidb/issues/46321) [#48352](https://github.com/pingcap/tidb/issues/48352) @[lance6716](https://github.com/lance6716) + - Fix the issue that data import fails because HTTP retry requests do not use the current request content [#47930](https://github.com/pingcap/tidb/issues/47930) @[lance6716](https://github.com/lance6716) + - Remove unnecessary `get_regions` calls in physical import mode [#45507](https://github.com/pingcap/tidb/issues/45507) @[mittalrishabh](https://github.com/mittalrishabh) diff --git a/releases/release-7.1.4.md b/releases/release-7.1.4.md new file mode 100644 index 0000000000000..9f7629016e269 --- /dev/null +++ b/releases/release-7.1.4.md @@ -0,0 +1,185 @@ +--- +title: TiDB 7.1.4 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.1.4. +--- + +# TiDB 7.1.4 Release Notes + +Release date: March 11, 2024 + +TiDB version: 7.1.4 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.1/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.1/production-deployment-using-tiup) + +## Compatibility changes + +- To reduce the overhead of log printing, TiFlash changes the default value of `logger.level` from `"debug"` to `"info"` [#8641](https://github.com/pingcap/tiflash/issues/8641) @[JaySon-Huang](https://github.com/JaySon-Huang) +- Introduce the TiKV configuration item [`gc.num-threads`](https://docs.pingcap.com/tidb/v6.5/tikv-configuration-file#num-threads-new-in-v658) to set the number of GC threads when `enable-compaction-filter` is `false` [#16101](https://github.com/tikv/tikv/issues/16101) @[tonyxuqqi](https://github.com/tonyxuqqi) + +## Improvements + ++ TiDB + + - Enhance the ability to convert `OUTER JOIN` to `INNER JOIN` in specific scenarios [#49616](https://github.com/pingcap/tidb/issues/49616) @[qw4990](https://github.com/qw4990) + - When `force-init-stats` is set to `true`, TiDB waits for statistics initialization to finish before providing services during TiDB startup. This setting no longer blocks the startup of HTTP servers, which enables users to continue monitoring [#50854](https://github.com/pingcap/tidb/issues/50854) @[hawkingrei](https://github.com/hawkingrei) + ++ TiKV + + - When TiKV detects the existence of corrupted SST files, it logs the specific reasons for the corruption [#16308](https://github.com/tikv/tikv/issues/16308) @[overvenus](https://github.com/overvenus) + ++ PD + + - Improve the speed of PD automatically updating cluster status when the backup cluster is disconnected [#6883](https://github.com/tikv/pd/issues/6883) @[disksing](https://github.com/disksing) + ++ TiFlash + + - Reduce the impact of background GC tasks on read and write task latency [#8650](https://github.com/pingcap/tiflash/issues/8650) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Reduce the impact of disk performance jitter on read latency [#8583](https://github.com/pingcap/tiflash/issues/8583) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + Backup & Restore (BR) + + - Support creating databases in batch during data restore [#50767](https://github.com/pingcap/tidb/issues/50767) @[Leavrth](https://github.com/Leavrth) + - Improve the table creation performance of the `RESTORE` statement in scenarios with large datasets [#48301](https://github.com/pingcap/tidb/issues/48301) @[Leavrth](https://github.com/Leavrth) + - Improve the speed of merging SST files during data restore by using a more efficient algorithm [#50613](https://github.com/pingcap/tidb/issues/50613) @[Leavrth](https://github.com/Leavrth) + - Support ingesting SST files in batch during data restore [#16267](https://github.com/tikv/tikv/issues/16267) @[3pointer](https://github.com/3pointer) + - Print the information of the slowest Region that affects global checkpoint advancement in logs and metrics during log backups [#51046](https://github.com/pingcap/tidb/issues/51046) @[YuJuncen](https://github.com/YuJuncen) + - Remove an outdated compatibility check when using Google Cloud Storage (GCS) as the external storage [#50533](https://github.com/pingcap/tidb/issues/50533) @[lance6716](https://github.com/lance6716) + - Implement a lock mechanism to avoid executing multiple log backup truncation tasks (`br log truncate`) simultaneously [#49414](https://github.com/pingcap/tidb/issues/49414) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - When the downstream is Kafka, the topic expression allows `schema` to be optional and supports specifying a topic name directly [#9763](https://github.com/pingcap/tiflow/issues/9763) @[3AceShowHand](https://github.com/3AceShowHand) + - Support [querying the downstream synchronization status of a changefeed](https://docs.pingcap.com/tidb/v7.1/ticdc-open-api-v2#query-whether-a-specific-replication-task-is-completed), which helps you determine whether the upstream data changes received by TiCDC have been synchronized to the downstream system completely [#10289](https://github.com/pingcap/tiflow/issues/10289) @[hongyunyan](https://github.com/hongyunyan) + - Support searching TiCDC logs in the TiDB Dashboard [#10263](https://github.com/pingcap/tiflow/issues/10263) @[CharlesCheung96](https://github.com/CharlesCheung96) + + + TiDB Lightning + + - Improve the performance in scenarios where multiple tables are imported by removing the lock operation when executing `ALTER TABLE` [#50105](https://github.com/pingcap/tidb/issues/50105) @[D3Hunter](https://github.com/D3Hunter) + +## Bug fixes + ++ TiDB + + - Fix the issue that the `DELETE` and `UPDATE` statements using index lookup might report an error when `tidb_multi_statement_mode` mode is enabled [#50012](https://github.com/pingcap/tidb/issues/50012) @[tangenta](https://github.com/tangenta) + - Fix the issue that CTE queries might report an error `type assertion for CTEStorageMap failed` during the retry process [#46522](https://github.com/pingcap/tidb/issues/46522) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue of excessive statistical error in constructing statistics caused by Golang's implicit conversion algorithm [#49801](https://github.com/pingcap/tidb/issues/49801) @[qw4990](https://github.com/qw4990) + - Fix the issue that errors might be returned during the concurrent merging of global statistics for partitioned tables [#48713](https://github.com/pingcap/tidb/issues/48713) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue of wrong query results due to TiDB incorrectly eliminating constant values in `group by` [#38756](https://github.com/pingcap/tidb/issues/38756) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that `BIT` type columns might cause query errors due to decode failures when they are involved in calculations of some functions [#49566](https://github.com/pingcap/tidb/issues/49566) [#50850](https://github.com/pingcap/tidb/issues/50850) [#50855](https://github.com/pingcap/tidb/issues/50855) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that `LIMIT` in multi-level nested `UNION` queries might become ineffective [#49874](https://github.com/pingcap/tidb/issues/49874) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the auto-increment ID allocation reports an error due to concurrent conflicts when using an auto-increment column with `AUTO_ID_CACHE=1` [#50519](https://github.com/pingcap/tidb/issues/50519) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the `Column ... in from clause is ambiguous` error that might occur when a query uses `NATURAL JOIN` [#32044](https://github.com/pingcap/tidb/issues/32044) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that enforced sorting might become ineffective when a query uses optimizer hints (such as `STREAM_AGG()`) that enforce sorting and its execution plan contains `IndexMerge` [#49605](https://github.com/pingcap/tidb/issues/49605) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that query results are incorrect due to `STREAM_AGG()` incorrectly handling CI [#49902](https://github.com/pingcap/tidb/issues/49902) @[wshwsh12](https://github.com/wshwsh12) + - Fix the goroutine leak issue that might occur when the `HashJoin` operator fails to spill to disk [#50841](https://github.com/pingcap/tidb/issues/50841) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that hints cannot be used in `REPLACE INTO` statements [#34325](https://github.com/pingcap/tidb/issues/34325) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that executing queries containing the `GROUP_CONCAT(ORDER BY)` syntax might return errors [#49986](https://github.com/pingcap/tidb/issues/49986) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that using a multi-valued index to access an empty JSON array might return incorrect results [#50125](https://github.com/pingcap/tidb/issues/50125) @[YangKeao](https://github.com/YangKeao) + - Fix the goroutine leak issue that occurs when the memory usage of CTE queries exceeds limits [#50337](https://github.com/pingcap/tidb/issues/50337) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that using old interfaces might cause inconsistent metadata for tables [#49751](https://github.com/pingcap/tidb/issues/49751) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that executing `UNIQUE` index lookup with an `ORDER BY` clause might cause an error [#49920](https://github.com/pingcap/tidb/issues/49920) @[jackysp](https://github.com/jackysp) + - Fix the issue that common hints do not take effect in `UNION ALL` statements [#50068](https://github.com/pingcap/tidb/issues/50068) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that a query containing the IndexHashJoin operator gets stuck when memory exceeds `tidb_mem_quota_query` [#49033](https://github.com/pingcap/tidb/issues/49033) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that `UPDATE` or `DELETE` statements containing `WITH RECURSIVE` CTEs might produce incorrect results [#48969](https://github.com/pingcap/tidb/issues/48969) @[winoros](https://github.com/winoros) + - Fix the issue that histogram statistics might not be parsed into readable strings when the histogram boundary contains `NULL` [#49823](https://github.com/pingcap/tidb/issues/49823) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that TiDB might panic when a query contains the Apply operator and the `fatal error: concurrent map writes` error occurs [#50347](https://github.com/pingcap/tidb/issues/50347) @[SeaRise](https://github.com/SeaRise) + - Fix the `Can't find column ...` error that might occur when aggregate functions are used for group calculations [#50926](https://github.com/pingcap/tidb/issues/50926) @[qw4990](https://github.com/qw4990) + - Fix the issue that TiDB returns wrong query results when processing `ENUM` or `SET` types by constant propagation [#49440](https://github.com/pingcap/tidb/issues/49440) @[winoros](https://github.com/winoros) + - Fix the issue that the completion times of two DDL tasks with dependencies are incorrectly sequenced [#49498](https://github.com/pingcap/tidb/issues/49498) @[tangenta](https://github.com/tangenta) + - Fix the issue that TiDB might panic when using the `EXECUTE` statement to execute `PREPARE STMT` after the `tidb_enable_prepared_plan_cache` system variable is enabled and then disabled [#49344](https://github.com/pingcap/tidb/issues/49344) @[qw4990](https://github.com/qw4990) + - Fix the issue that `LIMIT` and `OPRDERBY` might be invalid in nested `UNION` queries [#49377](https://github.com/pingcap/tidb/issues/49377) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the `LEADING` hint does not take effect in `UNION ALL` statements [#50067](https://github.com/pingcap/tidb/issues/50067) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `COMMIT` or `ROLLBACK` operation executed through `COM_STMT_EXECUTE` fails to terminate transactions that have timed out [#49151](https://github.com/pingcap/tidb/issues/49151) @[zyguan](https://github.com/zyguan) + - Fix the issue that illegal optimizer hints might cause valid hints to be ineffective [#49308](https://github.com/pingcap/tidb/issues/49308) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that Daylight Saving Time is displayed incorrectly in some time zones [#49586](https://github.com/pingcap/tidb/issues/49586) @[overvenus](https://github.com/overvenus) + - Fix the issue that executing `SELECT INTO OUTFILE` using the `PREPARE` method incorrectly returns a success message instead of an error [#49166](https://github.com/pingcap/tidb/issues/49166) @[qw4990](https://github.com/qw4990) + - Fix the issue that TiDB might panic when performing a rolling upgrade using `tiup cluster upgrade/start` due to an interaction issue with PD [#50152](https://github.com/pingcap/tidb/issues/50152) @[zimulala](https://github.com/zimulala) + - Fix the issue that the expected optimization does not take effect when adding an index to an empty table [#49682](https://github.com/pingcap/tidb/issues/49682) @[zimulala](https://github.com/zimulala) + - Fix the issue that TiDB might OOM when a large number of tables or partitions are created [#50077](https://github.com/pingcap/tidb/issues/50077) @[zimulala](https://github.com/zimulala) + - Fix the issue that adding an index might cause inconsistent index data when the network is unstable [#49773](https://github.com/pingcap/tidb/issues/49773) @[tangenta](https://github.com/tangenta) + - Fix the execution order of DDL jobs to prevent TiCDC from receiving out-of-order DDLs [#49498](https://github.com/pingcap/tidb/issues/49498) @[tangenta](https://github.com/tangenta) + - Fix the issue that the `tidb_gogc_tuner_threshold` system variable is not adjusted accordingly after the `tidb_server_memory_limit` variable is modified [#48180](https://github.com/pingcap/tidb/issues/48180) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the query result of a range partitioned table is incorrect in some cases due to wrong partition pruning [#50082](https://github.com/pingcap/tidb/issues/50082) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that DDL operations such as renaming tables are stuck when the `CREATE TABLE` statement contains specific partitions or constraints [#50972](https://github.com/pingcap/tidb/issues/50972) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that getting the default value of a column returns an error if the column default value is dropped [#50043](https://github.com/pingcap/tidb/issues/50043) [#51324](https://github.com/pingcap/tidb/issues/51324) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the monitoring metric `tidb_statistics_auto_analyze_total` on Grafana is not displayed as an integer [#51051](https://github.com/pingcap/tidb/issues/51051) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `tidb_merge_partition_stats_concurrency` variable does not take effect when `auto analyze` is processing partitioned tables [#47594](https://github.com/pingcap/tidb/issues/47594) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `index out of range` error might occur when a query involves JOIN operations [#42588](https://github.com/pingcap/tidb/issues/42588) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that wrong results might be returned when TiFlash late materialization processes associated columns [#49241](https://github.com/pingcap/tidb/issues/49241) [#51204](https://github.com/pingcap/tidb/issues/51204) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that parallel `Apply` might generate incorrect results when the table has a clustered index [#51372](https://github.com/pingcap/tidb/issues/51372) @[guo-shaoge](https://github.com/guo-shaoge) + ++ TiKV + + - Fix the issue that hibernated Regions are not promptly awakened in exceptional circumstances [#16368](https://github.com/tikv/tikv/issues/16368) @[LykxSassinator](https://github.com/LykxSassinator) + - Fix the issue that the entire Region becomes unavailable when one replica is offline, by checking the last heartbeat time of all replicas of the Region before taking a node offline [#16465](https://github.com/tikv/tikv/issues/16465) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that table properties stored in RocksDB might be inaccurate when Titan is enabled [#16319](https://github.com/tikv/tikv/issues/16319) @[hicqu](https://github.com/hicqu) + - Fix the issue that executing `tikv-ctl compact-cluster` fails when a cluster has TiFlash nodes [#16189](https://github.com/tikv/tikv/issues/16189) @[frew](https://github.com/frew) + - Fix the issue that TiKV might panic when gRPC threads are checking `is_shutdown` [#16236](https://github.com/tikv/tikv/issues/16236) @[pingyu](https://github.com/pingyu) + - Fix the issue that TiDB and TiKV might produce inconsistent results when processing `DECIMAL` arithmetic multiplication truncation [#16268](https://github.com/tikv/tikv/issues/16268) @[solotzg](https://github.com/solotzg) + - Fix the issue that `cast_duration_as_time` might return incorrect results [#16211](https://github.com/tikv/tikv/issues/16211) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that TiKV converts the time zone incorrectly for Brazil and Egypt [#16220](https://github.com/tikv/tikv/issues/16220) @[overvenus](https://github.com/overvenus) + - Fix the issue that JSON integers greater than the maximum `INT64` value but less than the maximum `UINT64` value are parsed as `FLOAT64` by TiKV, resulting in inconsistency with TiDB [#16512](https://github.com/tikv/tikv/issues/16512) @[YangKeao](https://github.com/YangKeao) + ++ PD + + - Fix the issue that slots are not fully deleted in a resource group client, which causes the number of the allocated tokens to be less than the specified value [#7346](https://github.com/tikv/pd/issues/7346) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that some TSO logs do not print the error cause [#7496](https://github.com/tikv/pd/issues/7496) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that the default resource group accumulates unnecessary tokens when `BURSTABLE` is enabled [#7206](https://github.com/tikv/pd/issues/7206) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that there is no output when the `evict-leader-scheduler` interface is called [#7672](https://github.com/tikv/pd/issues/7672) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the memory leak issue that occurs when `watch etcd` is not turned off correctly [#7807](https://github.com/tikv/pd/issues/7807) @[rleungx](https://github.com/rleungx) + - Fix the issue that data race occurs when the `MergeLabels` function is called [#7535](https://github.com/tikv/pd/issues/7535) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that TiDB Dashboard fails to get the TiKV profile when TLS is enabled [#7561](https://github.com/tikv/pd/issues/7561) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the orphan peer is deleted when the number of replicas does not meet the requirements [#7584](https://github.com/tikv/pd/issues/7584) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that `available_stores` is calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode [#7221](https://github.com/tikv/pd/issues/7221) @[disksing](https://github.com/disksing) + - Fix the issue that `canSync` and `hasMajority` might be calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode when the configuration of Placement Rules is complex [#7201](https://github.com/tikv/pd/issues/7201) @[disksing](https://github.com/disksing) + - Fix the issue that the primary AZ cannot add TiKV nodes when the secondary AZ is down for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode [#7218](https://github.com/tikv/pd/issues/7218) @[disksing](https://github.com/disksing) + - Fix the issue that querying resource groups in batch might cause PD to panic [#7206](https://github.com/tikv/pd/issues/7206) @[nolouch](https://github.com/nolouch) + - Fix the issue that querying a Region without a leader using `pd-ctl` might cause PD to panic [#7630](https://github.com/tikv/pd/issues/7630) @[rleungx](https://github.com/rleungx) + - Fix the issue that the PD monitoring item `learner-peer-count` does not synchronize the old value after a leader switch [#7728](https://github.com/tikv/pd/issues/7728) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that PD cannot read resource limitations when it is started with `systemd` [#7628](https://github.com/tikv/pd/issues/7628) @[bufferflies](https://github.com/bufferflies) + ++ TiFlash + + - Fix the issue that TiFlash might panic due to unstable network connections with PD during replica migration [#8323](https://github.com/pingcap/tiflash/issues/8323) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash incorrectly handles `ENUM` when the `ENUM` value is 0 [#8311](https://github.com/pingcap/tiflash/issues/8311) @[solotzg](https://github.com/solotzg) + - Fix the random invalid memory access issue that might occur with `GREATEST` or `LEAST` functions containing constant string parameters [#8604](https://github.com/pingcap/tiflash/issues/8604) @[windtalker](https://github.com/windtalker) + - Fix the issue that the `lowerUTF8` and `upperUTF8` functions do not allow characters in different cases to occupy different bytes [#8484](https://github.com/pingcap/tiflash/issues/8484) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that short queries executed successfully print excessive info logs [#8592](https://github.com/pingcap/tiflash/issues/8592) @[windtalker](https://github.com/windtalker) + - Fix the issue that the memory usage increases significantly due to slow queries [#8564](https://github.com/pingcap/tiflash/issues/8564) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that TiFlash panics after executing `ALTER TABLE ... MODIFY COLUMN ... NOT NULL`, which changes nullable columns to non-nullable [#8419](https://github.com/pingcap/tiflash/issues/8419) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that after terminating a query, TiFlash crashes due to concurrent data conflicts when a large number of tasks on TiFlash are canceled at the same time [#7432](https://github.com/pingcap/tiflash/issues/7432) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that TiFlash might crash during remote reads [#8685](https://github.com/pingcap/tiflash/issues/8685) @[zanmato1984](https://github.com/zanmato1984) + - Fix the issue that TiFlash Anti Semi Join might return incorrect results when the join includes non-equivalent conditions [#8791](https://github.com/pingcap/tiflash/issues/8791) @[windtalker](https://github.com/windtalker) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that stopping a log backup task causes TiDB to crash [#50839](https://github.com/pingcap/tidb/issues/50839) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that data restore is slowed down due to absence of a leader on a TiKV node [#50566](https://github.com/pingcap/tidb/issues/50566) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that log backup gets stuck after changing the TiKV IP address on the same node [#50445](https://github.com/pingcap/tidb/issues/50445) @[3pointer](https://github.com/3pointer) + - Fix the issue that BR cannot retry when encountering an error while reading file content from S3 [#49942](https://github.com/pingcap/tidb/issues/49942) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the `Unsupported collation` error is reported when you restore data from backups of an old version [#49466](https://github.com/pingcap/tidb/issues/49466) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Fix the issue that the changefeed reports an error after `TRUNCATE PARTITION` is executed on the upstream table [#10522](https://github.com/pingcap/tiflow/issues/10522) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that the changefeed `resolved ts` does not advance in extreme cases [#10157](https://github.com/pingcap/tiflow/issues/10157) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that the Syncpoint table might be incorrectly replicated [#10576](https://github.com/pingcap/tiflow/issues/10576) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that after filtering out `add table partition` events is configured in `ignore-event`, TiCDC does not replicate other types of DML changes for related partitions to the downstream [#10524](https://github.com/pingcap/tiflow/issues/10524) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the file sequence number generated by the storage service might not increment correctly when using the storage sink [#10352](https://github.com/pingcap/tiflow/issues/10352) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that TiCDC returns the `ErrChangeFeedAlreadyExists` error when concurrently creating multiple changefeeds [#10430](https://github.com/pingcap/tiflow/issues/10430) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that `snapshot lost caused by GC` is not reported in time when resuming a changefeed and the `checkpoint-ts` of the changefeed is smaller than the GC safepoint of TiDB [#10463](https://github.com/pingcap/tiflow/issues/10463) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC fails to validate `TIMESTAMP` type checksum due to time zone mismatch after data integrity validation for single-row data is enabled [#10573](https://github.com/pingcap/tiflow/issues/10573) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Fix the issue that a wrong binlog event type in the task configuration causes upgrade failures [#10282](https://github.com/pingcap/tiflow/issues/10282) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that a table with `shard_row_id_bits` causes the schema tracker to fail to initialize [#10308](https://github.com/pingcap/tiflow/issues/10308) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning reports an error when encountering invalid symbolic link files during file scanning [#49423](https://github.com/pingcap/tidb/issues/49423) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB Lightning fails to correctly parse date values containing `0` when `NO_ZERO_IN_DATE` is not included in `sql_mode` [#50757](https://github.com/pingcap/tidb/issues/50757) @[GMHDBJD](https://github.com/GMHDBJD) diff --git a/releases/release-7.1.5.md b/releases/release-7.1.5.md new file mode 100644 index 0000000000000..525360875600b --- /dev/null +++ b/releases/release-7.1.5.md @@ -0,0 +1,119 @@ +--- +title: TiDB 7.1.5 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.1.5. +--- + +# TiDB 7.1.5 Release Notes + +Release date: April 26, 2024 + +TiDB version: 7.1.5 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.1/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.1/production-deployment-using-tiup) + +## Compatibility changes + +- Add a TiKV configuration item [`track-and-verify-wals-in-manifest`](https://docs.pingcap.com/tidb/v7.1/tikv-configuration-file#track-and-verify-wals-in-manifest-new-in-v659-and-v715) for RocksDB, which helps you investigate possible corruption of Write Ahead Log (WAL) [#16549](https://github.com/tikv/tikv/issues/16549) @[v01dstar](https://github.com/v01dstar) + +## Improvements + ++ TiDB + + - Support loading Regions in batch from PD to speed up the conversion process from the KV range to Regions when querying large tables [#51326](https://github.com/pingcap/tidb/issues/51326) @[SeaRise](https://github.com/SeaRise) + - Optimize the issue that the `ANALYZE` statement blocks the metadata lock [#47475](https://github.com/pingcap/tidb/issues/47475) @[wjhuang2016](https://github.com/wjhuang2016) + - Add a timeout mechanism for LDAP authentication to avoid the issue of resource lock (RLock) not being released in time [#51883](https://github.com/pingcap/tidb/issues/51883) @[YangKeao](https://github.com/YangKeao) + ++ TiKV + + - Add slow logs for peer and store messages [#16600](https://github.com/tikv/tikv/issues/16600) @[Connor1996](https://github.com/Connor1996) + - Avoid performing IO operations on snapshot files in raftstore threads to improve TiKV stability [#16564](https://github.com/tikv/tikv/issues/16564) @[Connor1996](https://github.com/Connor1996) + ++ PD + + - Upgrade the etcd version to v3.4.30 [#7904](https://github.com/tikv/pd/issues/7904) @[JmPotato](https://github.com/JmPotato) + ++ Tools + + + Backup & Restore (BR) + + - Support automatically abandoning log backup tasks when encountering a large checkpoint lag, to avoid prolonged blocking GC and potential cluster issues [#50803](https://github.com/pingcap/tidb/issues/50803) @[RidRisR](https://github.com/RidRisR) + - Add PITR integration test cases to cover compatibility testing for log backup and adding index acceleration [#51987](https://github.com/pingcap/tidb/issues/51987) @[Leavrth](https://github.com/Leavrth) + - Remove the invalid verification for active DDL jobs when log backup starts [#52733](https://github.com/pingcap/tidb/issues/52733) @[Leavrth](https://github.com/Leavrth) + +## Bug fixes + ++ TiDB + + - Fix the issue that querying JSON of `BINARY` type might cause an error in some cases [#51547](https://github.com/pingcap/tidb/issues/51547) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that query execution using MPP might lead to incorrect query results when a SQL statement contains `JOIN` and the `SELECT` list in the statement contains only constants [#50358](https://github.com/pingcap/tidb/issues/50358) @[yibin87](https://github.com/yibin87) + - Fix the issue that the `init-stats` process might cause TiDB to panic and the `load stats` process to quit [#51581](https://github.com/pingcap/tidb/issues/51581) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the TiDB server is marked as health before the initialization is complete [#51596](https://github.com/pingcap/tidb/issues/51596) @[shenqidebaozi](https://github.com/shenqidebaozi) + - Fix the issue that `ALTER TABLE ... COMPACT TIFLASH REPLICA` might incorrectly end when the primary key type is `VARCHAR` [#51810](https://github.com/pingcap/tidb/issues/51810) @[breezewish](https://github.com/breezewish) + - Fix the issue that TiDB crashes when `shuffleExec` quits unexpectedly [#48230](https://github.com/pingcap/tidb/issues/48230) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `SURVIVAL_PREFERENCES` attribute might not appear in the output of the `SHOW CREATE PLACEMENT POLICY` statement under certain conditions [#51699](https://github.com/pingcap/tidb/issues/51699) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that after the time window for automatic statistics updates is configured, statistics might still be updated outside that time window [#49552](https://github.com/pingcap/tidb/issues/49552) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that query results might be incorrect when the `HAVING` clause in a subquery contains correlated columns [#51107](https://github.com/pingcap/tidb/issues/51107) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `approx_percentile` function might cause TiDB panic [#40463](https://github.com/pingcap/tidb/issues/40463) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that the query result is incorrect when the `IN()` predicate contains `NULL` [#51560](https://github.com/pingcap/tidb/issues/51560) @[winoros](https://github.com/winoros) + - Fix the issue that the configuration file does not take effect when it contains an invalid configuration item [#51399](https://github.com/pingcap/tidb/issues/51399) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that `EXCHANGE PARTITION` incorrectly processes foreign keys [#51807](https://github.com/pingcap/tidb/issues/51807) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that querying the `TIDB_HOT_REGIONS` table might incorrectly return `INFORMATION_SCHEMA` tables [#50810](https://github.com/pingcap/tidb/issues/50810) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the type returned by the `IFNULL` function is inconsistent with MySQL [#51765](https://github.com/pingcap/tidb/issues/51765) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the TTL feature causes data hotspots due to incorrect data range splitting in some cases [#51527](https://github.com/pingcap/tidb/issues/51527) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that TiDB keeps sending probe requests to a TiFlash node that has been offline [#46602](https://github.com/pingcap/tidb/issues/46602) @[zyguan](https://github.com/zyguan) + - Fix the issue that AutoID Leader change might cause the value of the auto-increment column to decrease in the case of `AUTO_ID_CACHE=1` [#52600](https://github.com/pingcap/tidb/issues/52600) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that executing `INSERT IGNORE` might result in inconsistency between the unique index and the data [#51784](https://github.com/pingcap/tidb/issues/51784) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that adding a unique index might cause TiDB to panic [#52312](https://github.com/pingcap/tidb/issues/52312) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the Window function might panic when there is a related subquery in it [#42734](https://github.com/pingcap/tidb/issues/42734) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `init-stats` process might cause TiDB to panic and the `load stats` process to quit [#51581](https://github.com/pingcap/tidb/issues/51581) @[hawkingrei](https://github.com/hawkingrei) + - Fix the performance regression issue caused by disabling predicate pushdown in TableDual [#50614](https://github.com/pingcap/tidb/issues/50614) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that query results might be incorrect when the `HAVING` clause in a subquery contains correlated columns [#51107](https://github.com/pingcap/tidb/issues/51107) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `EXPLAIN` statement might display incorrect column IDs in the result when statistics for certain columns are not fully loaded [#52207](https://github.com/pingcap/tidb/issues/52207) @[time-and-fate](https://github.com/time-and-fate) + ++ TiKV + + - Fix the issue that resolve-ts is blocked when a stale Region peer ignores the GC message [#16504](https://github.com/tikv/tikv/issues/16504) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that inactive Write Ahead Logs (WALs) in RocksDB might corrupt data [#16705](https://github.com/tikv/tikv/issues/16705) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the monitoring metric `tikv_unified_read_pool_thread_count` has no data in some cases [#16629](https://github.com/tikv/tikv/issues/16629) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that during the execution of an optimistic transaction, if other transactions initiate the resolving lock operation on it, there is a small chance that the atomicity of the transaction might be broken if the transaction's primary key has data that was previously committed in Async Commit or 1PC mode [#16620](https://github.com/tikv/tikv/issues/16620) @[MyonKeminta](https://github.com/MyonKeminta) + ++ PD + + - Fix the issue that the scheduling of write hotspots might break placement policy constraints [#7848](https://github.com/tikv/pd/issues/7848) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that the query result of `SHOW CONFIG` includes the deprecated configuration item `trace-region-flow` [#7917](https://github.com/tikv/pd/issues/7917) @[rleungx](https://github.com/rleungx) + - Fix the issue that the scaling progress is not correctly displayed [#7726](https://github.com/tikv/pd/issues/7726) @[CabinfeverB](https://github.com/CabinfeverB) + ++ TiFlash + + - Fix incorrect `local_region_num` values in logs [#8895](https://github.com/pingcap/tiflash/issues/8895) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that querying generated columns returns an error [#8787](https://github.com/pingcap/tiflash/issues/8787) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the `ENUM` column might cause TiFlash to crash during chunk encoding [#8674](https://github.com/pingcap/tiflash/issues/8674) @[yibin87](https://github.com/yibin87) + - Fix the issue that TiFlash might panic when you insert data to columns with invalid default values in non-strict `sql_mode` [#8803](https://github.com/pingcap/tiflash/issues/8803) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that if Region migration, split, or merge occurs after the precision of a `TIME` column is modified, queries might fail [#8601](https://github.com/pingcap/tiflash/issues/8601) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that removing a log backup task after it is paused does not immediately restore the GC safepoint [#52082](https://github.com/pingcap/tidb/issues/52082) @[3pointer](https://github.com/3pointer) + - Fix the issue that too many logs are printed when a full backup fails [#51572](https://github.com/pingcap/tidb/issues/51572) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that BR could not back up the `AUTO_RANDOM` ID allocation progress if the `AUTO_RANDOM` column is in a composite clustered index [#52255](https://github.com/pingcap/tidb/issues/52255) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that TiKV panics when a full backup fails to find a peer in some extreme cases [#16394](https://github.com/tikv/tikv/issues/16394) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that a PD connection failure could cause the TiDB instance where the log backup advancer owner is located to panic [#52597](https://github.com/pingcap/tidb/issues/52597) @[YuJuncen](https://github.com/YuJuncen) + - Fix an unstable test case [#52547](https://github.com/pingcap/tidb/issues/52547) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the global checkpoint of log backup is advanced ahead of the actual backup file write point due to TiKV restart, which might cause a small amount of backup data loss [#16809](https://github.com/tikv/tikv/issues/16809) @[YuJuncen](https://github.com/YuJuncen) + - Fix a rare issue that special event timing might cause the data loss in log backup [#16739](https://github.com/tikv/tikv/issues/16739) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the issue that TiCDC fails to execute the `Exchange Partition ... With Validation` DDL downstream after it is written upstream, causing the changefeed to get stuck [#10859](https://github.com/pingcap/tiflow/issues/10859) @[hongyunyan](https://github.com/hongyunyan) + - Fix the issue that `snapshot lost caused by GC` is not reported in time when resuming a changefeed and the `checkpoint-ts` of the changefeed is smaller than the GC safepoint of TiDB [#10463](https://github.com/pingcap/tiflow/issues/10463) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC panics when scheduling table replication tasks [#10613](https://github.com/pingcap/tiflow/issues/10613) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that data is written to a wrong CSV file due to wrong BarrierTS in scenarios where DDL statements are executed frequently [#10668](https://github.com/pingcap/tiflow/issues/10668) @[lidezhu](https://github.com/lidezhu) + - Fix the issue that a changefeed with eventual consistency enabled might fail when the object storage sink encounters a temporary failure [#10710](https://github.com/pingcap/tiflow/issues/10710) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the old value part of `open-protocol` incorrectly outputs the default value according to the `STRING` type instead of its actual type [#10803](https://github.com/pingcap/tiflow/issues/10803) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning panics when importing an empty table of Parquet format [#52518](https://github.com/pingcap/tidb/issues/52518) @[kennytm](https://github.com/kennytm) + - Fix the issue that sensitive information in logs is printed in server mode [#36374](https://github.com/pingcap/tidb/issues/36374) @[kennytm](https://github.com/kennytm) diff --git a/releases/release-7.2.0.md b/releases/release-7.2.0.md new file mode 100644 index 0000000000000..d86a486af1116 --- /dev/null +++ b/releases/release-7.2.0.md @@ -0,0 +1,332 @@ +--- +title: TiDB 7.2.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 7.2.0. +--- + +# TiDB 7.2.0 Release Notes + +Release date: June 29, 2023 + +TiDB version: 7.2.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.2/quick-start-with-tidb) + +7.2.0 introduces the following key features and improvements: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeatureDescription
Scalability and PerformanceResource groups support managing runaway queries (experimental)You can now manage query timeout with more granularity, allowing for different behaviors based on query classifications. Queries meeting your specified threshold can be deprioritized or terminated. +
TiFlash supports the pipeline execution model (experimental)TiFlash supports a pipeline execution model to optimize thread resource control.
SQLSupport a new SQL statement, IMPORT INTO, for data import (experimental)To simplify the deployment and maintenance of TiDB Lightning, TiDB introduces a new SQL statement IMPORT INTO, which integrates physical import mode of TiDB Lightning, including remote import from Amazon S3 or Google Cloud Storage (GCS) directly into TiDB.
DB Operations and ObservabilityDDL supports pause and resume operations (experimental)This new capability lets you temporarily suspend resource-intensive DDL operations, such as index creation, to conserve resources and minimize the impact on online traffic. You can seamlessly resume these operations when ready, without the need to cancel and restart. This feature enhances resource utilization, improves user experience, and streamlines schema changes.
+ +## Feature details + +### Performance + +* Support pushing down the following two [window functions](/tiflash/tiflash-supported-pushdown-calculations.md) to TiFlash [#7427](https://github.com/pingcap/tiflash/issues/7427) @[xzhangxian1008](https://github.com/xzhangxian1008) + + * `FIRST_VALUE` + * `LAST_VALUE` + +* TiFlash supports the pipeline execution model (experimental) [#6518](https://github.com/pingcap/tiflash/issues/6518) @[SeaRise](https://github.com/SeaRise) + + Prior to v7.2.0, each task in the TiFlash engine must individually request thread resources during execution. TiFlash controls the number of tasks to limit thread resource usage and prevent overuse, but this issue could not be completely eliminated. To address this problem, starting from v7.2.0, TiFlash introduces a pipeline execution model. This model centrally manages all thread resources and schedules task execution uniformly, maximizing the utilization of thread resources while avoiding resource overuse. To enable or disable the pipeline execution model, modify the [`tidb_enable_tiflash_pipeline_model`](https://docs.pingcap.com/tidb/v7.2/system-variables#tidb_enable_tiflash_pipeline_model-new-in-v720) system variable. + + For more information, see [documentation](/tiflash/tiflash-pipeline-model.md). + +* TiFlash reduces the latency of schema replication [#7630](https://github.com/pingcap/tiflash/issues/7630) @[hongyunyan](https://github.com/hongyunyan) + + When the schema of a table changes, TiFlash needs to replicate the latest schema from TiKV in a timely manner. Before v7.2.0, when TiFlash accesses table data and detects a table schema change within a database, TiFlash needs to replicate the schemas of all tables in this database again, including those tables without TiFlash replicas. As a result, in a database with a large number of tables, even if you only need to read data from a single table using TiFlash, you might experience significant latency to wait for TiFlash to complete the schema replication of all tables. + + In v7.2.0, TiFlash optimizes the schema replication mechanism and supports only replicating schemas of tables with TiFlash replicas. When a schema change is detected for a table with TiFlash replicas, TiFlash only replicates the schema of that table, which reduces the latency of schema replication of TiFlash and minimizes the impact of DDL operations on TiFlash data replication. This optimization is automatically applied and does not require any manual configuration. + +* Improve the performance of statistics collection [#44725](https://github.com/pingcap/tidb/issues/44725) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + TiDB v7.2.0 optimizes the statistics collection strategy, skipping some of the duplicate information and information that is of little value to the optimizer. The overall speed of statistics collection has been improved by 30%. This improvement allows TiDB to update the statistics of the database in a more timely manner, making the generated execution plans more accurate, thus improving the overall database performance. + + By default, statistics collection skips the columns of the `JSON`, `BLOB`, `MEDIUMBLOB`, and `LONGBLOB` types. You can modify the default behavior by setting the [`tidb_analyze_skip_column_types`](/system-variables.md#tidb_analyze_skip_column_types-new-in-v720) system variable. TiDB supports skipping the `JSON`, `BLOB`, and `TEXT` types and their subtypes. + + For more information, see [documentation](/system-variables.md#tidb_analyze_skip_column_types-new-in-v720). + +* Improve the performance of checking data and index consistency [#43693](https://github.com/pingcap/tidb/issues/43693) @[wjhuang2016](https://github.com/wjhuang2016) + + The [`ADMIN CHECK [TABLE|INDEX]`](/sql-statements/sql-statement-admin-check-table-index.md) statement is used to check the consistency between data in a table and its corresponding indexes. In v7.2.0, TiDB optimizes the method for checking data consistency and improves the execution efficiency of [`ADMIN CHECK [TABLE|INDEX]`](/sql-statements/sql-statement-admin-check-table-index.md) greatly. In scenarios with large amounts of data, this optimization can provide a performance boost of hundreds of times. + + The optimization is enabled by default ([`tidb_enable_fast_table_check`](/system-variables.md#tidb_enable_fast_table_check-new-in-v720) is `ON` by default) to greatly reduce the time required for data consistency checks in large-scale tables and enhance operational efficiency. + + For more information, see [documentation](/system-variables.md#tidb_enable_fast_table_check-new-in-v720). + +### Reliability + +* Automatically manage queries that consume more resources than expected (experimental) [#43691](https://github.com/pingcap/tidb/issues/43691) @[Connor1996](https://github.com/Connor1996) @[CabinfeverB](https://github.com/CabinfeverB) @[glorv](https://github.com/glorv) @[HuSharp](https://github.com/HuSharp) @[nolouch](https://github.com/nolouch) + + The most common challenge to database stability is the degradation of overall database performance caused by abrupt SQL performance problems. There are many causes for SQL performance issues, such as new SQL statements that have not been fully tested, drastic changes in data volume, and abrupt changes in execution plans. These issues are difficult to completely avoid at the root. TiDB v7.2.0 provides the ability to manage queries that consume more resources than expected. This feature can quickly reduce the scope of impact when a performance issue occurs. + + To manage these queries, you can set the maximum execution time of queries for a resource group. When the execution time of a query exceeds this limit, the query is automatically deprioritized or cancelled. You can also set a period of time to immediately match identified queries by text or execution plan. This helps prevent high concurrency of the problematic queries during the identification phase that could consume more resources than expected. + + Automatic management of queries that consume more resources than expected provides you with an effective means to quickly respond to unexpected query performance problems. This feature can reduce the impact of the problem on overall database performance, thereby improving database stability. + + For more information, see [documentation](/tidb-resource-control.md#manage-queries-that-consume-more-resources-than-expected-runaway-queries). + +* Enhance the capability of creating a binding according to a historical execution plan [#39199](https://github.com/pingcap/tidb/issues/39199) @[qw4990](https://github.com/qw4990) + + TiDB v7.2.0 enhances the capability of [creating a binding according to a historical execution plan](/sql-plan-management.md#create-a-binding-according-to-a-historical-execution-plan). This feature improves the parsing and binding process for complex statements, making the bindings more stable, and supports the following new hints: + + - [`AGG_TO_COP()`](/optimizer-hints.md#agg_to_cop) + - [`LIMIT_TO_COP()`](/optimizer-hints.md#limit_to_cop) + - [`ORDER_INDEX`](/optimizer-hints.md#order_indext1_name-idx1_name--idx2_name-) + - [`NO_ORDER_INDEX()`](/optimizer-hints.md#no_order_indext1_name-idx1_name--idx2_name-) + + For more information, see [documentation](/sql-plan-management.md). + +* Introduce the Optimizer Fix Controls mechanism to provide fine-grained control over optimizer behaviors [#43169](https://github.com/pingcap/tidb/issues/43169) @[time-and-fate](https://github.com/time-and-fate) + + To generate more reasonable execution plans, the behavior of the TiDB optimizer evolves over product iterations. However, in some particular scenarios, the changes might lead to performance regression. TiDB v7.2.0 introduces Optimizer Fix Controls to let you control some of the fine-grained behaviors of the optimizer. This enables you to roll back or control some new changes. + + Each controllable behavior is described by a GitHub issue corresponding to the fix number. All controllable behaviors are listed in [Optimizer Fix Controls](/optimizer-fix-controls.md). You can set a target value for one or more behaviors by setting the [`tidb_opt_fix_control`](/system-variables.md#tidb_opt_fix_control-new-in-v653-and-v710) system variable to achieve behavior control. + + The Optimizer Fix Controls mechanism helps you control the TiDB optimizer at a granular level. It provides a new means of fixing performance issues caused by the upgrade process and improves the stability of TiDB. + + For more information, see [documentation](/optimizer-fix-controls.md). + +* Lightweight statistics initialization becomes generally available (GA) [#42160](https://github.com/pingcap/tidb/issues/42160) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + + Starting from v7.2.0, the lightweight statistics initialization feature becomes GA. Lightweight statistics initialization can significantly reduce the number of statistics that must be loaded during startup, thus improving the speed of loading statistics. This feature increases the stability of TiDB in complex runtime environments and reduces the impact on the overall service when TiDB nodes restart. + + For newly created clusters of v7.2.0 or later versions, TiDB loads lightweight statistics by default during TiDB startup and will wait for the loading to finish before providing services. For clusters upgraded from earlier versions, you can set the TiDB configuration items [`lite-init-stats`](/tidb-configuration-file.md#lite-init-stats-new-in-v710) and [`force-init-stats`](/tidb-configuration-file.md#force-init-stats-new-in-v657-and-v710) to `true` to enable this feature. + + For more information, see [documentation](/statistics.md#load-statistics). + +### SQL + +* Support the `CHECK` constraints [#41711](https://github.com/pingcap/tidb/issues/41711) @[fzzf678](https://github.com/fzzf678) + + Starting from v7.2.0, you can use `CHECK` constraints to restrict the values of one or more columns in a table to meet your specified conditions. When a `CHECK` constraint is added to a table, TiDB checks whether the constraint is satisfied before inserting or updating data in the table. Only the data that satisfies the constraint can be written. + + This feature is disabled by default. You can set the [`tidb_enable_check_constraint`](/system-variables.md#tidb_enable_check_constraint-new-in-v720) system variable to `ON` to enable it. + + For more information, see [documentation](/constraints.md#check). + +### DB operations + +* DDL jobs support pause and resume operations (experimental) [#18015](https://github.com/pingcap/tidb/issues/18015) @[godouxm](https://github.com/godouxm) + + Before TiDB v7.2.0, when a DDL job encounters a business peak during execution, you can only manually cancel the DDL job to reduce its impact on the business. In v7.2.0, TiDB introduces pause and resume operations for DDL jobs. These operations let you pause DDL jobs during a peak and resume them after the peak ends, thus avoiding impact on your application workloads. + + For example, you can pause and resume multiple DDL jobs using `ADMIN PAUSE DDL JOBS` or `ADMIN RESUME DDL JOBS`: + + ```sql + ADMIN PAUSE DDL JOBS 1,2; + ADMIN RESUME DDL JOBS 1,2; + ``` + + For more information, see [documentation](/ddl-introduction.md#ddl-related-commands). + +### Data migration + +* Introduce a new SQL statement `IMPORT INTO` to improve data import efficiency greatly (experimental) [#42930](https://github.com/pingcap/tidb/issues/42930) @[D3Hunter](https://github.com/D3Hunter) + + The `IMPORT INTO` statement integrates the [Physical Import Mode](/tidb-lightning/tidb-lightning-physical-import-mode.md) capability of TiDB Lightning. With this statement, you can quickly import data in formats such as CSV, SQL, and PARQUET into an empty table in TiDB. This import method eliminates the need for a separate deployment and management of TiDB Lightning, thereby reducing the complexity of data import and greatly improving import efficiency. + + For data files stored in Amazon S3 or GCS, when the [TiDB Distributed eXecution Framework (DXF)](/tidb-distributed-execution-framework.md) is enabled, `IMPORT INTO` also supports splitting a data import job into multiple sub-jobs and scheduling them to multiple TiDB nodes for parallel import, which further enhances import performance. + + For more information, see [documentation](/sql-statements/sql-statement-import-into.md). + +* TiDB Lightning supports importing source files with the Latin-1 character set into TiDB [#44434](https://github.com/pingcap/tidb/issues/44434) @[lance6716](https://github.com/lance6716) + + With this feature, you can directly import source files with the Latin-1 character set into TiDB using TiDB Lightning. Before v7.2.0, importing such files requires your additional preprocessing or conversion. Starting from v7.2.0, you only need to specify `character-set = "latin1"` when configuring the TiDB Lightning import task. Then, TiDB Lightning automatically handles the character set conversion during the import process to ensure data integrity and accuracy. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v7.1.0 to the current version (v7.2.0). If you are upgrading from v7.0.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### Behavior changes + +- When processing update event, TiCDC splits an event into delete and insert events if the primary key or non-null unique index value is modified in the event. For more information, see [documentation](/ticdc/ticdc-split-update-behavior.md#transactions-containing-a-single-update-change). + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`last_insert_id`](/system-variables.md#last_insert_id) | Modified | Changes the maximum value from `9223372036854775807` to `18446744073709551615` to be consistent with that of MySQL. | +| [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache) | Modified | Changes the default value from `OFF` to `ON` after further tests, meaning that non-prepared execution plan cache is enabled. | +| [`tidb_remove_orderby_in_subquery`](/system-variables.md#tidb_remove_orderby_in_subquery-new-in-v610) | Modified | Changes the default value from `OFF` to `ON` after further tests, meaning that the optimizer removes the `ORDER BY` clause in a subquery. | +| [`tidb_analyze_skip_column_types`](/system-variables.md#tidb_analyze_skip_column_types-new-in-v720) | Newly added | Controls which types of columns are skipped for statistics collection when executing the `ANALYZE` command to collect statistics. The variable is only applicable for [`tidb_analyze_version = 2`](/system-variables.md#tidb_analyze_version-new-in-v510). When using the syntax of `ANALYZE TABLE t COLUMNS c1, ..., cn`, if the type of a specified column is included in `tidb_analyze_skip_column_types`, the statistics of this column will not be collected. | +| [`tidb_enable_check_constraint`](/system-variables.md#tidb_enable_check_constraint-new-in-v720) | Newly added | Controls whether to enable `CHECK` constraints. The default value is `OFF`, which means this feature is disabled. | +| [`tidb_enable_fast_table_check`](/system-variables.md#tidb_enable_fast_table_check-new-in-v720) | Newly added | Controls whether to use a checksum-based approach to quickly check the consistency of data and indexes in a table. The default value is `ON`, which means this feature is enabled. | +| [`tidb_enable_tiflash_pipeline_model`](https://docs.pingcap.com/tidb/v7.2/system-variables#tidb_enable_tiflash_pipeline_model-new-in-v720) | Newly added | Controls whether to enable the new execution model of TiFlash, the [pipeline model](/tiflash/tiflash-pipeline-model.md). The default value is `OFF`, which means the pipeline model is disabled. | +| [`tidb_expensive_txn_time_threshold`](/system-variables.md#tidb_expensive_txn_time_threshold-new-in-v720) | Newly added | Controls the threshold for logging expensive transactions, which is 600 seconds by default. When the duration of a transaction exceeds the threshold, and the transaction is neither committed nor rolled back, it is considered an expensive transaction and will be logged. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`lite-init-stats`](/tidb-configuration-file.md#lite-init-stats-new-in-v710) | Modified | Changes the default value from `false` to `true` after further tests, meaning that TiDB uses lightweight statistics initialization by default during TiDB startup to improve the initialization efficiency. | +| TiDB | [`force-init-stats`](/tidb-configuration-file.md#force-init-stats-new-in-v657-and-v710) | Modified | Changes the default value from `false` to `true` to align with [`lite-init-stats`](/tidb-configuration-file.md#lite-init-stats-new-in-v710), meaning that TiDB waits for statistics initialization to finish before providing services during TiDB startup. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].compaction-guard-min-output-file-size](/tikv-configuration-file.md#compaction-guard-min-output-file-size) | Modified | Changes the default value from `"8MB"` to `"1MB"` to reduce the data volume of compaction tasks in RocksDB. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].optimize-filters-for-memory](/tikv-configuration-file.md#optimize-filters-for-memory-new-in-v720) | Newly added | Controls whether to generate Bloom/Ribbon filters that minimize memory internal fragmentation. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].periodic-compaction-seconds](/tikv-configuration-file.md#periodic-compaction-seconds-new-in-v720) | Newly added | Controls the time interval for periodic compaction. SST files with updates older than this value will be selected for compaction and rewritten to the same level where these SST files originally reside. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].ribbon-filter-above-level](/tikv-configuration-file.md#ribbon-filter-above-level-new-in-v720) | Newly added | Controls whether to use Ribbon filters for levels greater than or equal to this value and use non-block-based bloom filters for levels less than this value. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].ttl](/tikv-configuration-file.md#ttl-new-in-v720) | Newly added | SST files with updates older than the TTL will be automatically selected for compaction. | +| TiDB Lightning | `send-kv-pairs` | Deprecated | Starting from v7.2.0, the parameter `send-kv-pairs` is deprecated. You can use [`send-kv-size`](/tidb-lightning/tidb-lightning-configuration.md) to control the maximum size of one request when sending data to TiKV in physical import mode. | +| TiDB Lightning | [`character-set`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Modified | Introduces a new value option `latin1` for the supported character sets of data import. You can use this option to import source files with the Latin-1 character set. | +| TiDB Lightning | [`send-kv-size`](/tidb-lightning/tidb-lightning-configuration.md) | Newly added | Specify the maximum size of one request when sending data to TiKV in physical import mode. When the size of key-value pairs reaches the specified threshold, TiDB Lightning will immediately send them to TiKV. This avoids the OOM problems caused by TiDB Lightning nodes accumulating too many key-value pairs in memory when importing large wide tables. By adjusting this parameter, you can find a balance between memory usage and import speed, improving the stability and efficiency of the import process. | +| Data Migration | [`strict-optimistic-shard-mode`](/dm/feature-shard-merge-optimistic.md) | Newly added | This configuration item is used to be compatible with the DDL shard merge behavior in TiDB Data Migration v2.0. You can enable this configuration item in optimistic mode. After this is enabled, the replication task will be interrupted when it encounters a Type 2 DDL statement. In scenarios where there are dependencies between DDL changes in multiple tables, a timely interruption can be made. You need to manually process the DDL statements of each table before resuming the replication task to ensure data consistency between the upstream and the downstream. | +| TiCDC | [`sink.protocol`](/ticdc/ticdc-changefeed-config.md) | Modified | Introduces a new value option `"open-protocol"` when the downstream is Kafka. Specifies the protocol format used for encoding messages. | +| TiCDC | [`sink.delete-only-output-handle-key-columns`](/ticdc/ticdc-changefeed-config.md) | Newly added | Specifies the output of DELETE events. This parameter is valid only for `"canal-json"` and `"open-protocol"` protocols. The default value is `false`, which means outputting all columns. When you set it to `true`, only primary key columns or unique index columns are output. | + +## Improvements + ++ TiDB + + - Optimize the logic of constructing index scan range so that it supports converting complex conditions into index scan range [#41572](https://github.com/pingcap/tidb/issues/41572) [#44389](https://github.com/pingcap/tidb/issues/44389) @[xuyifangreeneyes](https://github.com/xuyifangreeneyes) + - Add new monitoring metrics `Stale Read OPS` and `Stale Read Traffic` [#43325](https://github.com/pingcap/tidb/issues/43325) @[you06](https://github.com/you06) + - When the retry leader of stale read encounters a lock, TiDB forcibly retries with the leader after resolving the lock, which avoids unnecessary overhead [#43659](https://github.com/pingcap/tidb/issues/43659) @[you06](https://github.com/you06) + - Use estimated time to calculate stale read ts and reduce the overhead of stale read [#44215](https://github.com/pingcap/tidb/issues/44215) @[you06](https://github.com/you06) + - Add logs and system variables for long-running transactions [#41471](https://github.com/pingcap/tidb/issues/41471) @[crazycs520](https://github.com/crazycs520) + - Support connecting to TiDB through the compressed MySQL protocol, which improves the performance of data-intensive queries under low bandwidth networks and saves bandwidth costs. This supports both `zlib` and `zstd` based compression. [#22605](https://github.com/pingcap/tidb/issues/22605) @[dveeden](https://github.com/dveeden) + - Recognize both `utf8` and `utf8bm3` as the legacy three-byte UTF-8 character set encodings, which facilitates the migration of tables with legacy UTF-8 encodings from MySQL 8.0 to TiDB [#26226](https://github.com/pingcap/tidb/issues/26226) @[dveeden](https://github.com/dveeden) + - Support using `:=` for assignment in `UPDATE` statements [#44751](https://github.com/pingcap/tidb/issues/44751) @[CbcWestwolf](https://github.com/CbcWestwolf) + ++ TiKV + + - Support configuring the retry interval of PD connections in scenarios such as connection request failures using `pd.retry-interval` [#14964](https://github.com/tikv/tikv/issues/14964) @[rleungx](https://github.com/rleungx) + - Optimize the resource control scheduling algorithm by incorporating the global resource usage [#14604](https://github.com/tikv/tikv/issues/14604) @[Connor1996](https://github.com/Connor1996) + - Use gzip compression for `check_leader` requests to reduce traffic [#14553](https://github.com/tikv/tikv/issues/14553) @[you06](https://github.com/you06) + - Add related metrics for `check_leader` requests [#14658](https://github.com/tikv/tikv/issues/14658) @[you06](https://github.com/you06) + - Provide detailed time information during TiKV handling write commands [#12362](https://github.com/tikv/tikv/issues/12362) @[cfzjywxk](https://github.com/cfzjywxk) + ++ PD + + - Use a separate gRPC connection for PD leader election to prevent the impact of other requests [#6403](https://github.com/tikv/pd/issues/6403) @[rleungx](https://github.com/rleungx) + - Enable the bucket splitting by default to mitigate hotspot issues in multi-Region scenarios [#6433](https://github.com/tikv/pd/issues/6433) @[bufferflies](https://github.com/bufferflies) + ++ Tools + + + Backup & Restore (BR) + + - Support access to Azure Blob Storage by shared access signature (SAS) [#44199](https://github.com/pingcap/tidb/issues/44199) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Optimize the structure of the directory where data files are stored when a DDL operation occurs in the scenario of replication to an object storage service [#8891](https://github.com/pingcap/tiflow/issues/8891) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support the OAUTHBEARER authentication in the scenario of replication to Kafka [#8865](https://github.com/pingcap/tiflow/issues/8865) @[hi-rustin](https://github.com/Rustin170506) + - Add the option of outputting only the handle keys for the `DELETE` operation in the scenario of replication to Kafka [#9143](https://github.com/pingcap/tiflow/issues/9143) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Support reading compressed binlogs in MySQL 8.0 as a data source for incremental replication [#6381](https://github.com/pingcap/tiflow/issues/6381) @[dveeden](https://github.com/dveeden) + + + TiDB Lightning + + - Optimize the retry mechanism during import to avoid errors caused by leader switching [#44263](https://github.com/pingcap/tidb/issues/44263) @[lance6716](https://github.com/lance6716) + - Verify checksum through SQL after the import to improve stability of verification [#41941](https://github.com/pingcap/tidb/issues/41941) @[GMHDBJD](https://github.com/GMHDBJD) + - Optimize TiDB Lightning OOM issues when importing wide tables [#43853](https://github.com/pingcap/tidb/issues/43853) @[D3Hunter](https://github.com/D3Hunter) + +## Bug fixes + ++ TiDB + + - Fix the issue that the query with CTE causes TiDB to hang [#43749](https://github.com/pingcap/tidb/issues/43749) [#36896](https://github.com/pingcap/tidb/issues/36896) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the `min, max` query result is incorrect [#43805](https://github.com/pingcap/tidb/issues/43805) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `SHOW PROCESSLIST` statement cannot display the TxnStart of the transaction of the statement with a long subquery time [#40851](https://github.com/pingcap/tidb/issues/40851) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the stale read global optimization does not take effect due to the lack of `TxnScope` in Coprocessor tasks [#43365](https://github.com/pingcap/tidb/issues/43365) @[you06](https://github.com/you06) + - Fix the issue that follower read does not handle flashback errors before retrying, which causes query errors [#43673](https://github.com/pingcap/tidb/issues/43673) @[you06](https://github.com/you06) + - Fix the issue that data and indexes are inconsistent when the `ON UPDATE` statement does not correctly update the primary key [#44565](https://github.com/pingcap/tidb/issues/44565) @[zyguan](https://github.com/zyguan) + - Modify the upper limit of the `UNIX_TIMESTAMP()` function to `3001-01-19 03:14:07.999999 UTC` to be consistent with that of MySQL 8.0.28 or later versions [#43987](https://github.com/pingcap/tidb/issues/43987) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that adding an index fails in the ingest mode [#44137](https://github.com/pingcap/tidb/issues/44137) @[tangenta](https://github.com/tangenta) + - Fix the issue that canceling a DDL task in the rollback state causes errors in related metadata [#44143](https://github.com/pingcap/tidb/issues/44143) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that using `memTracker` with cursor fetch causes memory leaks [#44254](https://github.com/pingcap/tidb/issues/44254) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that dropping a database causes slow GC progress [#33069](https://github.com/pingcap/tidb/issues/33069) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB returns an error when the corresponding rows in partitioned tables cannot be found in the probe phase of index join [#43686](https://github.com/pingcap/tidb/issues/43686) @[AilinKid](https://github.com/AilinKid) @[mjonss](https://github.com/mjonss) + - Fix the issue that there is no warning when using `SUBPARTITION` to create partitioned tables [#41198](https://github.com/pingcap/tidb/issues/41198) [#41200](https://github.com/pingcap/tidb/issues/41200) @[mjonss](https://github.com/mjonss) + - Fix the issue that when a query is killed because it exceeds `MAX_EXECUTION_TIME`, the returned error message is inconsistent with that of MySQL [#43031](https://github.com/pingcap/tidb/issues/43031) @[dveeden](https://github.com/dveeden) + - Fix the issue that the `LEADING` hint does not support querying block aliases [#44645](https://github.com/pingcap/tidb/issues/44645) @[qw4990](https://github.com/qw4990) + - Modify the return type of the `LAST_INSERT_ID()` function from VARCHAR to LONGLONG to be consistent with that of MySQL [#44574](https://github.com/pingcap/tidb/issues/44574) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that incorrect results might be returned when using a common table expression (CTE) in statements with non-correlated subqueries [#44051](https://github.com/pingcap/tidb/issues/44051) @[winoros](https://github.com/winoros) + - Fix the issue that Join Reorder might cause incorrect outer join results [#44314](https://github.com/pingcap/tidb/issues/44314) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `PREPARE stmt FROM "ANALYZE TABLE xxx"` might be killed by `tidb_mem_quota_query` [#44320](https://github.com/pingcap/tidb/issues/44320) @[chrysan](https://github.com/chrysan) + ++ TiKV + + - Fix the issue that the transaction returns an incorrect value when TiKV handles stale pessimistic lock conflicts [#13298](https://github.com/tikv/tikv/issues/13298) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that in-memory pessimistic lock might cause flashback failures and data inconsistency [#13303](https://github.com/tikv/tikv/issues/13303) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the fair lock might be incorrect when TiKV handles stale requests [#13298](https://github.com/tikv/tikv/issues/13298) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that `autocommit` and `point get replica read` might break linearizability [#14715](https://github.com/tikv/tikv/issues/14715) @[cfzjywxk](https://github.com/cfzjywxk) + ++ PD + + - Fix the issue that redundant replicas cannot be automatically repaired in some corner cases [#6573](https://github.com/tikv/pd/issues/6573) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Fix the issue that queries might consume more memory than needed when the data on the Join build side is very large and contains many small string type columns [#7416](https://github.com/pingcap/tiflash/issues/7416) @[yibin87](https://github.com/yibin87) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that `checksum mismatch` is falsely reported in some cases [#44472](https://github.com/pingcap/tidb/issues/44472) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that `resolved lock timeout` is falsely reported in some cases [#43236](https://github.com/pingcap/tidb/issues/43236) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiDB might panic when restoring statistics information [#44490](https://github.com/pingcap/tidb/issues/44490) @[tangenta](https://github.com/tangenta) + + + TiCDC + + - Fix the issue that Resolved TS does not advance properly in some cases [#8963](https://github.com/pingcap/tiflow/issues/8963) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the `UPDATE` operation cannot output old values when the Avro or CSV protocol is used [#9086](https://github.com/pingcap/tiflow/issues/9086) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue of excessive downstream pressure caused by reading downstream metadata too frequently when replicating data to Kafka [#8959](https://github.com/pingcap/tiflow/issues/8959) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue of too many downstream logs caused by frequently setting the downstream bidirectional replication-related variables when replicating data to TiDB or MySQL [#9180](https://github.com/pingcap/tiflow/issues/9180) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the PD node crashing causes the TiCDC node to restart [#8868](https://github.com/pingcap/tiflow/issues/8868) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that TiCDC cannot create a changefeed with a downstream Kafka-on-Pulsar [#8892](https://github.com/pingcap/tiflow/issues/8892) @[hi-rustin](https://github.com/Rustin170506) + + + TiDB Lightning + + - Fix the TiDB Lightning panic issue when `experimental.allow-expression-index` is enabled and the default value is UUID [#44497](https://github.com/pingcap/tidb/issues/44497) @[lichunzhu](https://github.com/lichunzhu) + - Fix the TiDB Lightning panic issue when a task exits while dividing a data file [#43195](https://github.com/pingcap/tidb/issues/43195) @[lance6716](https://github.com/lance6716) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [asjdf](https://github.com/asjdf) +- [blacktear23](https://github.com/blacktear23) +- [Cavan-xu](https://github.com/Cavan-xu) +- [darraes](https://github.com/darraes) +- [demoManito](https://github.com/demoManito) +- [dhysum](https://github.com/dhysum) +- [happy-v587](https://github.com/happy-v587) +- [jiyfhust](https://github.com/jiyfhust) +- [L-maple](https://github.com/L-maple) +- [nyurik](https://github.com/nyurik) +- [SeigeC](https://github.com/SeigeC) +- [tangjingyu97](https://github.com/tangjingyu97) diff --git a/releases/release-7.4.0.md b/releases/release-7.4.0.md new file mode 100644 index 0000000000000..fcc60a550e1d6 --- /dev/null +++ b/releases/release-7.4.0.md @@ -0,0 +1,500 @@ +--- +title: TiDB 7.4.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 7.4.0. +--- + +# TiDB 7.4.0 Release Notes + +Release date: October 12, 2023 + +TiDB version: 7.4.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.4/quick-start-with-tidb) + +7.4.0 introduces the following key features and improvements: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeatureDescription
Reliability and AvailabilityImprove the performance and stability of IMPORT INTO and ADD INDEX operations via global sort (experimental)Before v7.4.0, tasks such as ADD INDEX or IMPORT INTO using the TiDB Distributed eXecution Framework (DXF) meant localized and partial sorting, which ultimately led to TiKV doing a lot of extra work to make up for the partial sorting. These jobs also required TiDB nodes to allocate local disk space for sorting, before loading to TiKV.
With the introduction of the Global Sort feature in v7.4.0, data is temporarily stored in external shared storage (S3 in this version) for global sorting before being loaded into TiKV. This eliminates the need for TiKV to consume extra resources and significantly improves the performance and stability of operations like ADD INDEX and IMPORT INTO.
Resource control for background tasks (experimental)In v7.1.0, the Resource Control feature was introduced to mitigate resource and storage access interference between workloads. TiDB v7.4.0 applies this control to background tasks as well. In v7.4.0, Resource Control now identifies and manages the resources produced by background tasks, such as auto-analyze, Backup & Restore, bulk load with TiDB Lightning, and online DDL. This will eventually apply to all background tasks.
TiFlash supports storage-computing separation and S3 (GA) TiFlash disaggregated storage and compute architecture and S3 shared storage become generally available: +
    +
  • Disaggregates TiFlash's compute and storage, which is a milestone for elastic HTAP resource utilization.
    • +
  • Supports using S3-based storage engine, which can provide shared storage at a lower cost.
    • +
+
SQLTiDB supports partition type management Before v7.4.0, Range/List partitioned tables support partition management operations such as TRUNCATE, EXCHANGE, ADD, DROP, and REORGANIZE, and Hash/Key partitioned tables support partition management operations such as ADD and COALESCE. +

Now TiDB also supports the following partition type management operations:

+
    +
  • Convert partitioned tables to non-partitioned tables
    • +
  • Partition existing non-partitioned tables
    • +
  • Modify partition types for existing tables
    • +
+
MySQL 8.0 compatibility: support collation utf8mb4_0900_ai_ciOne notable change in MySQL 8.0 is that the default character set is utf8mb4, and the default collation of utf8mb4 is utf8mb4_0900_ai_ci. TiDB v7.4.0 adding support for this enhances compatibility with MySQL 8.0 so that migrations and replications from MySQL 8.0 databases with the default collation are now much smoother.
DB Operations and ObservabilitySpecify the respective TiDB nodes to execute the IMPORT INTO and ADD INDEX SQL statements (experimental)You have the flexibility to specify whether to execute IMPORT INTO or ADD INDEX SQL statements on some of the existing TiDB nodes or newly added TiDB nodes. This approach enables resource isolation from the rest of the TiDB nodes, preventing any impact on business operations while ensuring optimal performance for executing the preceding SQL statements.
+ +## Feature details + +### Scalability + +* Support selecting the TiDB nodes to parallelly execute the backend `ADD INDEX` or `IMPORT INTO` tasks of the Distributed eXecution Framework (DXF) (experimental) [#46453](https://github.com/pingcap/tidb/pull/46453) @[ywqzzy](https://github.com/ywqzzy) + + Executing `ADD INDEX` or `IMPORT INTO` tasks in parallel in a resource-intensive cluster can consume a large amount of TiDB node resources, which can lead to cluster performance degradation. Starting from v7.4.0, you can use the system variable [`tidb_service_scope`](/system-variables.md#tidb_service_scope-new-in-v740) to control the service scope of each TiDB node under the [TiDB Distributed eXecution Framework (DXF)](/tidb-distributed-execution-framework.md). You can select several existing TiDB nodes or set the TiDB service scope for new TiDB nodes, and all parallel `ADD INDEX` and `IMPORT INTO` tasks only run on these nodes. This mechanism can avoid performance impact on existing services. + + For more information, see [documentation](/system-variables.md#tidb_service_scope-new-in-v740). + +* Enhance the Partitioned Raft KV storage engine (experimental) [#11515](https://github.com/tikv/tikv/issues/11515) [#12842](https://github.com/tikv/tikv/issues/12842) @[busyjay](https://github.com/busyjay) @[tonyxuqqi](https://github.com/tonyxuqqi) @[tabokie](https://github.com/tabokie) @[bufferflies](https://github.com/bufferflies) @[5kbpers](https://github.com/5kbpers) @[SpadeA-Tang](https://github.com/SpadeA-Tang) @[nolouch](https://github.com/nolouch) + + TiDB v6.6.0 introduces the Partitioned Raft KV storage engine as an experimental feature, which uses multiple RocksDB instances to store TiKV Region data, and the data of each Region is independently stored in a separate RocksDB instance. + + In v7.4.0, TiDB further improves the compatibility and stability of the Partitioned Raft KV storage engine. Through large-scale data testing, the compatibility with TiDB ecosystem tools and features such as DM, Dumpling, TiDB Lightning, TiCDC, BR, and PITR is ensured. Additionally, the Partitioned Raft KV storage engine provides more stable performance under mixed read and write workloads, making it especially suitable for write-heavy scenarios. Furthermore, each TiKV node now supports 8 core CPUs and can be configured with 8 TB data storage, and 64 GB memory. + + For more information, see [documentation](/partitioned-raft-kv.md). + +* TiFlash supports the disaggregated storage and compute architecture (GA) [#6882](https://github.com/pingcap/tiflash/issues/6882) @[JaySon-Huang](https://github.com/JaySon-Huang) @[JinheLin](https://github.com/JinheLin) @[breezewish](https://github.com/breezewish) @[lidezhu](https://github.com/lidezhu) @[CalvinNeo](https://github.com/CalvinNeo) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + + In v7.0.0, TiFlash introduces the disaggregated storage and compute architecture as an experimental feature. With a series of improvements, the disaggregated storage and compute architecture for TiFlash becomes GA starting from v7.4.0. + + In this architecture, TiFlash nodes are divided into two types (Compute Nodes and Write Nodes) and support object storage that is compatible with S3 API. Both types of nodes can be independently scaled for computing or storage capacities. In the disaggregated storage and compute architecture, you can use TiFlash in the same way as the coupled storage and compute architecture, such as creating TiFlash replicas, querying data, and specifying optimizer hints. + + Note that the TiFlash **disaggregated storage and compute architecture** and **coupled storage and compute architecture** cannot be used in the same cluster or converted to each other. You can configure which architecture to use when you deploy TiFlash. + + For more information, see [documentation](/tiflash/tiflash-disaggregated-and-s3.md). + +### Performance + +* Support pushing down the JSON operator `MEMBER OF` to TiKV [#46307](https://github.com/pingcap/tidb/issues/46307) @[wshwsh12](https://github.com/wshwsh12) + + * `value MEMBER OF(json_array)` + + For more information, see [documentation](/functions-and-operators/expressions-pushed-down.md). + +* Support pushing down window functions with any frame definition type to TiFlash [#7376](https://github.com/pingcap/tiflash/issues/7376) @[xzhangxian1008](https://github.com/xzhangxian1008) + + Before v7.4.0, TiFlash does not support window functions containing `PRECEDING` or `FOLLOWING`, and all window functions containing such frame definitions cannot be pushed down to TiFlash. Starting from v7.4.0, TiFlash supports frame definitions of all window functions. This feature is enabled automatically, and window functions containing frame definitions will be automatically pushed down to TiFlash for execution when the related requirements are met. + +* Introduce cloud storage-based global sort capability to improve the performance and stability of `ADD INDEX` and `IMPORT INTO` tasks in parallel execution (experimental) [#45719](https://github.com/pingcap/tidb/issues/45719) @[wjhuang2016](https://github.com/wjhuang2016) + + Before v7.4.0, when executing tasks like `ADD INDEX` or `IMPORT INTO` in the Distributed eXecution Framework (DXF), each TiDB node needs to allocate a significant amount of local disk space for sorting encoded index KV pairs and table data KV pairs. However, due to the lack of global sorting capability, there might be overlapping data between different TiDB nodes and within each individual node during the process. As a result, TiKV has to constantly perform compaction operations while importing these KV pairs into its storage engine, which impacts the performance and stability of `ADD INDEX` and `IMPORT INTO`. + + In v7.4.0, TiDB introduces the [Global Sort](/tidb-global-sort.md) feature. Instead of writing the encoded data locally and sorting it there, the data is now written to cloud storage for global sorting. Once sorted, both the indexed data and table data are imported into TiKV in parallel, thereby improving performance and stability. + + For more information, see [documentation](/tidb-global-sort.md). + +* Support caching execution plans for non-prepared statements (GA) [#36598](https://github.com/pingcap/tidb/issues/36598) @[qw4990](https://github.com/qw4990) + + TiDB v7.0.0 introduces non-prepared plan cache as an experimental feature to improve the load capacity of concurrent OLTP. In v7.4.0, this feature becomes GA. The execution plan cache will be applied to more scenarios, thereby improving the concurrent processing capacity of TiDB. + + Enabling the non-prepared plan cache might incur additional memory and CPU overhead and might not be suitable for all situations. Starting from v7.4.0, this feature is disabled by default. You can enable it using [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache) and control the cache size using [`tidb_session_plan_cache_size`](/system-variables.md#tidb_session_plan_cache_size-new-in-v710). + + Additionally, this feature does not support DML statements by default and has certain restrictions on SQL statements. For more details, see [Restrictions](/sql-non-prepared-plan-cache.md#restrictions). + + For more information, see [documentation](/sql-non-prepared-plan-cache.md). + +### Reliability + +* TiFlash supports query-level data spilling [#7738](https://github.com/pingcap/tiflash/issues/7738) @[windtalker](https://github.com/windtalker) + + Starting from v7.0.0, TiFlash supports controlling data spilling for three operators: `GROUP BY`, `ORDER BY`, and `JOIN`. This feature prevents issues such as query termination or system crashes when the data size exceeds the available memory. However, managing spilling for each operator individually can be cumbersome and ineffective for overall resource control. + + In v7.4.0, TiFlash introduces the query-level data spilling. By setting the memory limit for a query on a TiFlash node using [`tiflash_mem_quota_query_per_node`](/system-variables.md#tiflash_mem_quota_query_per_node-new-in-v740) and the memory ratio that triggers data spilling using [`tiflash_query_spill_ratio`](/system-variables.md#tiflash_query_spill_ratio-new-in-v740), you can conveniently manage the memory usage of a query and have better control over TiFlash memory resources. + + For more information, see [documentation](/tiflash/tiflash-spill-disk.md). + +* Support user-defined TiKV read timeout [#45380](https://github.com/pingcap/tidb/issues/45380) @[crazycs520](https://github.com/crazycs520) + + Normally, TiKV processes requests very quickly, in a matter of milliseconds. However, when a TiKV node encounters disk I/O jitter or network latency, the request processing time can increase significantly. In versions earlier than v7.4.0, the timeout limit for TiKV requests is fixed and unadjustable. Hence, TiDB has to wait for a fixed-duration timeout response when a TiKV node encounters issues, which results in a noticeable impact on application query performance during jitter. + + TiDB v7.4.0 introduces a new system variable [`tikv_client_read_timeout`](/system-variables.md#tikv_client_read_timeout-new-in-v740), which lets you customize the timeout for RPC read requests that TiDB sends to TiKV in a query. It means that when the request sent to a TiKV node is delayed due to disk or network issues, TiDB can time out faster and resend the request to other TiKV nodes, thus reducing query latency. If timeouts occur for all TiKV nodes, TiDB will retry using the default timeout. Additionally, you can also use the optimizer hint `/*+ SET_VAR(TIKV_CLIENT_READ_TIMEOUT=N) */` in a query to set the timeout for TiDB to send a TiKV RPC read request. This enhancement gives TiDB the flexibility to adapt to unstable network or storage environments, improving query performance and enhancing the user experience. + + For more information, see [documentation](/system-variables.md#tikv_client_read_timeout-new-in-v740). + +* Support temporarily modifying some system variable values using an optimizer hint [#45892](https://github.com/pingcap/tidb/issues/45892) @[winoros](https://github.com/winoros) + + TiDB v7.4.0 introduces the optimizer hint `SET_VAR()`, which is similar to that of MySQL 8.0. By including the hint `SET_VAR()` in SQL statements, you can temporarily modify the value of system variables during statement execution. This helps you set the environment for different statements. For example, you can actively increase the parallelism of resource-intensive SQL statements or change the optimizer behavior through variables. + + You can find the system variables that can be modified using the hint `SET_VAR()` in [system variables](/system-variables.md). It is strongly recommended not to modify variables that are not explicitly supported, as this might cause unpredictable behavior. + + For more information, see [documentation](/optimizer-hints.md). + +* TiFlash supports resource control [#7660](https://github.com/pingcap/tiflash/issues/7660) @[guo-shaoge](https://github.com/guo-shaoge) + + In TiDB v7.1.0, the resource control feature becomes generally available and provides resource management capabilities for TiDB and TiKV. In v7.4.0, TiFlash supports the resource control feature, improving the overall resource management capabilities of TiDB. The resource control of TiFlash is fully compatible with the existing TiDB resource control feature, and the existing resource groups will manage the resources of TiDB, TiKV, and TiFlash at the same time. + + To control whether to enable the TiFlash resource control feature, you can configure the TiFlash parameter `enable_resource_control`. After enabling this feature, TiFlash performs resource scheduling and management based on the resource group configuration of TiDB, ensuring the reasonable allocation and use of overall resources. + + For more information, see [documentation](/tidb-resource-control.md). + +* TiFlash supports the pipeline execution model (GA) [#6518](https://github.com/pingcap/tiflash/issues/6518) @[SeaRise](https://github.com/SeaRise) + + Starting from v7.2.0, TiFlash introduces a pipeline execution model. This model centrally manages all thread resources and schedules task execution uniformly, maximizing the utilization of thread resources while avoiding resource overuse. In v7.4.0, TiFlash improves the statistics of thread resource usage, and the pipeline execution model becomes a GA feature and is enabled by default. Since this feature is mutually dependent with the TiFlash resource control feature, TiDB v7.4.0 removes the variable `tidb_enable_tiflash_pipeline_model` used to control whether to enable the pipeline execution model in previous versions. Instead, you can enable or disable the pipeline execution model and the TiFlash resource control feature by configuring the TiFlash parameter `tidb_enable_resource_control`. + + For more information, see [documentation](/tiflash/tiflash-pipeline-model.md). + +* Add the option of optimizer mode [#46080](https://github.com/pingcap/tidb/issues/46080) @[time-and-fate](https://github.com/time-and-fate) + + In v7.4.0, TiDB introduces a new system variable [`tidb_opt_objective`](/system-variables.md#tidb_opt_objective-new-in-v740), which controls the estimation method used by the optimizer. The default value `moderate` maintains the previous behavior of the optimizer, where it uses runtime statistics to adjust estimations based on data changes. If this variable is set to `determinate`, the optimizer generates execution plans solely based on statistics without considering runtime corrections. + + For long-term stable OLTP applications or situations where you are confident in the existing execution plans, it is recommended to switch to `determinate` mode after testing. This reduces potential plan changes. + + For more information, see [documentation](/system-variables.md#tidb_opt_objective-new-in-v740). + +* TiDB resource control supports managing background tasks (experimental) [#44517](https://github.com/pingcap/tidb/issues/44517) @[glorv](https://github.com/glorv) + + Background tasks, such as data backup and automatic statistics collection, are low-priority but consume many resources. These tasks are usually triggered periodically or irregularly. During execution, they consume a lot of resources, thus affecting the performance of online high-priority tasks. Starting from v7.4.0, the TiDB resource control feature supports managing background tasks. This feature reduces the performance impact of low-priority tasks on online applications, enabling rational resource allocation, and greatly improving cluster stability. + + TiDB supports the following types of background tasks: + + - `lightning`: perform import tasks using [TiDB Lightning](/tidb-lightning/tidb-lightning-overview.md) or [`IMPORT INTO`](/sql-statements/sql-statement-import-into.md). + - `br`: perform backup and restore tasks using [BR](/br/backup-and-restore-overview.md). PITR is not supported. + - `ddl`: control the resource usage during the batch data write back phase of Reorg DDLs. + - `stats`: the [collect statistics](/statistics.md#collect-statistics) tasks that are manually executed or automatically triggered by TiDB. + + By default, the task types that are marked as background tasks are empty, and the management of background tasks is disabled. This default behavior is the same as that of versions prior to TiDB v7.4.0. To manage background tasks, you need to manually modify the background task types of the `default` resource group. + + For more information, see [documentation](/tidb-resource-control.md#manage-background-tasks). + +* Lock statistics becomes generally available (GA) [#46351](https://github.com/pingcap/tidb/issues/46351) @[hi-rustin](https://github.com/Rustin170506) + + In v7.4.0, [lock statistics](/statistics.md#lock-statistics) becomes generally available. Now, to ensure operational security, locking and unlocking statistics require the same privileges as collecting statistics. In addition, TiDB supports locking and unlocking statistics for specific partitions, providing greater flexibility. If you are confident in queries and execution plans in the database and want to prevent any changes from occurring, you can lock statistics to enhance stability. + + For more information, see [documentation](/statistics.md#lock-statistics). + +* Introduce a system variable to control whether to select hash joins for tables [#46695](https://github.com/pingcap/tidb/issues/46695) @[coderplay](https://github.com/coderplay) + + MySQL 8.0 introduces hash joins for tables as a new feature. This feature is primarily used to join two relatively large tables and result sets. However, for transactional workloads, or some applications running on MySQL 5.7, hash joins for tables might pose a performance risk. MySQL provides the [`optimizer_switch`](https://dev.mysql.com/doc/refman/8.0/en/switchable-optimizations.html#optflag_block-nested-loop) to control whether to select hash joins at the global or session level. + + Starting from v7.4.0, TiDB introduces the system variable [`tidb_opt_enable_hash_join`](/system-variables.md#tidb_opt_enable_hash_join-new-in-v656-v712-and-v740) to have control over hash joins for tables. It is enabled by default (`ON`). If you are sure that you do not need to select hash joins between tables in your execution plan, you can modify the variable to `OFF` to reduce the possibility of execution plan rollbacks and improve system stability. + + For more information, see [documentation](/system-variables.md#tidb_opt_enable_hash_join-new-in-v656-v712-and-v740). + +### SQL + +* TiDB supports partition type management [#42728](https://github.com/pingcap/tidb/issues/42728) @[mjonss](https://github.com/mjonss) + + Before v7.4.0, partition types of partitioned tables in TiDB cannot be modified. Starting from v7.4.0, TiDB supports modifying partitioned tables to non-partitioned tables or non-partitioned tables to partitioned tables, and supports changing partition types. Hence, now you can flexibly adjust the partition type and number for a partitioned table. For example, you can use the `ALTER TABLE t PARTITION BY ...` statement to modify the partition type. + + For more information, see [documentation](/partitioned-table.md#convert-a-partitioned-table-to-a-non-partitioned-table). + +* TiDB supports using the `ROLLUP` modifier and the `GROUPING` function [#44487](https://github.com/pingcap/tidb/issues/44487) @[AilinKid](https://github.com/AilinKid) + + The `WITH ROLLUP` modifier and `GROUPING` function are commonly used in data analysis for multi-dimensional data summarization. Starting from v7.4.0, you can use the `WITH ROLLUP` modifier and `GROUPING` function in the `GROUP BY` clause. For example, you can use the `WITH ROLLUP` modifier in the `SELECT ... FROM ... GROUP BY ... WITH ROLLUP` syntax. + + For more information, see [documentation](/functions-and-operators/group-by-modifier.md). + +### DB operations + +* Support collation `utf8mb4_0900_ai_ci` and `utf8mb4_0900_bin` [#37566](https://github.com/pingcap/tidb/issues/37566) @[YangKeao](https://github.com/YangKeao) @[zimulala](https://github.com/zimulala) @[bb7133](https://github.com/bb7133) + + TiDB v7.4.0 enhances the support for migrating data from MySQL 8.0 and adds two collations: `utf8mb4_0900_ai_ci` and `utf8mb4_0900_bin`. `utf8mb4_0900_ai_ci` is the default collation in MySQL 8.0. + + TiDB v7.4.0 also introduces the system variable `default_collation_for_utf8mb4` which is compatible with MySQL 8.0. This enables you to specify the default collation for the utf8mb4 character set and provides compatibility with migration or data replication from MySQL 5.7 or earlier versions. + + For more information, see [documentation](/character-set-and-collation.md#character-sets-and-collations-supported-by-tidb). + +### Observability + +* Support adding session connection IDs and session aliases to logs [#46071](https://github.com/pingcap/tidb/issues/46071) @[lcwangchao](https://github.com/lcwangchao) + + When you troubleshoot a SQL execution problem, it is often necessary to correlate the contents of TiDB component logs to pinpoint the root cause. Starting from v7.4.0, TiDB can write session connection IDs (`CONNECTION_ID`) to session-related logs, including TiDB logs, slow query logs, and slow logs from the coprocessor on TiKV. You can correlate the contents of several types of logs based on session connection IDs to improve troubleshooting and diagnostic efficiency. + + In addition, by setting the session-level system variable [`tidb_session_alias`](/system-variables.md#tidb_session_alias-new-in-v740), you can add custom identifiers to the logs mentioned above. With this ability to inject your application identification information into the logs, you can correlate the contents of the logs with the application, build the link from the application to the logs, and reduce the difficulty of diagnosis. + +* TiDB Dashboard supports displaying execution plans in a table view [#1589](https://github.com/pingcap/tidb-dashboard/issues/1589) @[baurine](https://github.com/baurine) + + In v7.4.0, TiDB Dashboard supports displaying execution plans on the **Slow Query** and **SQL Statement** pages in a table view to improve the diagnosis experience. + + For more information, see [documentation](/dashboard/dashboard-statement-details.md). + +### Data migration + +* Enhance the `IMPORT INTO` feature [#46704](https://github.com/pingcap/tidb/issues/46704) @[D3Hunter](https://github.com/D3Hunter) + + Starting from v7.4.0, you can add the `CLOUD_STORAGE_URI` option in the `IMPORT INTO` statement to enable the [Global Sort](/tidb-global-sort.md) feature (experimental), which helps boost import performance and stability. In the `CLOUD_STORAGE_URI` option, you can specify a cloud storage address for the encoded data. + + In addition, in v7.4.0, the `IMPORT INTO` feature introduces the following functionalities: + + - Support configuring the `Split_File` option, which allows you to split a large CSV file into multiple 256 MiB small CSV files for parallel processing, improving import performance. + - Support importing compressed CSV and SQL files. The supported compression formats include `.gzip`, `.gz`, `.zstd`, `.zst`, and `.snappy`. + + For more information, see [documentation](/sql-statements/sql-statement-import-into.md). + +* Dumpling supports the user-defined terminator when exporting data to CSV files [#46982](https://github.com/pingcap/tidb/issues/46982) @[GMHDBJD](https://github.com/GMHDBJD) + + Before v7.4.0, Dumpling uses `"\r\n"` as the line terminator when exporting data to a CSV file. As a result, certain downstream systems that only recognize `"\n"` as the terminator cannot parse the exported CSV file, or have to use a third-party tool for conversion before parsing the file. + + Starting from v7.4.0, Dumpling introduces a new parameter `--csv-line-terminator`. This parameter allows you to specify a desired terminator when you export data to a CSV file. This parameter supports `"\r\n"` and `"\n"`. The default terminator is `"\r\n"` to keep consistent with earlier versions. + + For more information, see [documentation](/dumpling-overview.md#option-list-of-dumpling). + +* TiCDC supports replicating data to Pulsar [#9413](https://github.com/pingcap/tiflow/issues/9413) @[yumchina](https://github.com/yumchina) @[asddongmen](https://github.com/asddongmen) + + Pulsar is a cloud-native and distributed message streaming platform that significantly enhances your real-time data streaming experience. Starting from v7.4.0, TiCDC supports replicating change data to Pulsar in `canal-json` format to achieve seamless integration with Pulsar. With this feature, TiCDC provides you with the ability to easily capture and replicate TiDB changes to Pulsar, offering new possibilities for data processing and analytics capabilities. You can develop your own consumer applications that read and process newly generated change data from Pulsar to meet specific business needs. + + For more information, see [documentation](/ticdc/ticdc-sink-to-pulsar.md). + +- TiCDC improves large message handling with claim-check pattern [#9153](https://github.com/pingcap/tiflow/issues/9153) @[3AceShowHand](https://github.com/3AceShowHand) + + Before v7.4.0, TiCDC is unable to send large messages exceeding the maximum message size (`max.message.bytes`) of Kafka to downstream. Starting from v7.4.0, when configuring a changefeed with Kafka as the downstream, you can specify an external storage location for storing the large message, and send a reference message containing the address of the large message in the external storage to Kafka. When consumers receive this reference message, they can retrieve the message content from the external storage address. + + For more information, see [documentation](/ticdc/ticdc-sink-to-kafka.md#send-large-messages-to-external-storage). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v7.3.0 to the current version (v7.4.0). If you are upgrading from v7.2.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### Behavior changes + +- Starting with v7.4.0, TiDB is compatible with essential features of MySQL 8.0, and `version()` returns the version prefixed with `8.0.11`. + +- After TiFlash is upgraded to v7.4.0 from an earlier version, in-place downgrading to the original version is not supported. This is because, starting from v7.4, TiFlash optimizes the data compaction logic of PageStorage V3 to reduce the read and write amplification generated during data compaction, which leads to changes to some of the underlying storage file names. + +- A [`TIDB_PARSE_TSO_LOGICAL()`](/functions-and-operators/tidb-functions.md#tidb-specific-functions) function is added to allow the extraction of the logical part of the TSO timestamp. + +- The [`information_schema.CHECK_CONSTRAINTS`](/information-schema/information-schema-check-constraints.md) table is added for improved compatibility with MySQL 8.0. + +- For transactions containing multiple changes, if the primary key or non-null unique index value is modified in the update event, TiCDC splits an event into delete and insert events and ensures that all events follow the sequence of delete events preceding insert events. For more information, see [documentation](/ticdc/ticdc-split-update-behavior.md#transactions-containing-multiple-update-changes). + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| `tidb_enable_tiflash_pipeline_model` | Deleted | This variable was used to control whether to enable the TiFlash pipeline execution model. Starting from v7.4.0, the TiFlash pipeline execution model is automatically enabled when the TiFlash resource control feature is enabled. | +| [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache) | Modified | Changes the default value from `ON` to `OFF` after further tests, meaning that non-prepared execution plan cache is disabled. | +| [`default_collation_for_utf8mb4`](/system-variables.md#default_collation_for_utf8mb4-new-in-v740) | Newly added | Controls the default collation for the `utf8mb4` character set. The default value is `utf8mb4_bin`. | +| [`tidb_cloud_storage_uri`](/system-variables.md#tidb_cloud_storage_uri-new-in-v740) | Newly added | Specifies the cloud storage URI to enable [Global Sort](/tidb-global-sort.md). | +| [`tidb_opt_enable_hash_join`](/system-variables.md#tidb_opt_enable_hash_join-new-in-v656-v712-and-v740) | Newly added | Controls whether the optimizer will select hash joins for tables. The value is `ON` by default. If set to `OFF`, the optimizer avoids selecting a hash join of a table unless there is no other execution plan available. | +| [`tidb_opt_objective`](/system-variables.md#tidb_opt_objective-new-in-v740) | Newly added | This variable controls the objective of the optimizer. `moderate` maintains the default behavior in versions prior to TiDB v7.4.0, where the optimizer tries to use more information to generate better execution plans. `determinate` mode tends to be more conservative and makes the execution plan more stable. | +| [`tidb_request_source_type`](/system-variables.md#tidb_request_source_type-new-in-v740) | Newly added | Explicitly specifies the task type for the current session, which is identified and controlled by [Resource Control](/tidb-resource-control.md). For example: `SET @@tidb_request_source_type = "background"`. | +| [`tidb_schema_version_cache_limit`](/system-variables.md#tidb_schema_version_cache_limit-new-in-v740) | Newly added | This variable limits how many historical schema versions can be cached in a TiDB instance. The default value is `16`, which means that TiDB caches 16 historical schema versions by default. | +| [`tidb_service_scope`](/system-variables.md#tidb_service_scope-new-in-v740) | Newly added | This variable is an instance-level system variable. You can use it to control the service scope of TiDB nodes under the [TiDB Distributed eXecution Framework (DXF)](/tidb-distributed-execution-framework.md). When you set `tidb_service_scope` of a TiDB node to `background`, the DXF schedules that TiDB node to execute DXF tasks, such as [`ADD INDEX`](/sql-statements/sql-statement-add-index.md) and [`IMPORT INTO`](/sql-statements/sql-statement-import-into.md). | +| [`tidb_session_alias`](/system-variables.md#tidb_session_alias-new-in-v740) | Newly added | Controls the value of the `session_alias` column in the logs related to the current session. | +| [`tiflash_mem_quota_query_per_node`](/system-variables.md#tiflash_mem_quota_query_per_node-new-in-v740) | Newly added | Limits the maximum memory usage for a query on a TiFlash node. When the memory usage of a query exceeds this limit, TiFlash returns an error and terminates the query. The default value is `0`, which means no limit.| +| [`tiflash_query_spill_ratio`](/system-variables.md#tiflash_query_spill_ratio-new-in-v740) | Newly added | Controls the threshold for TiFlash [query-level spilling](/tiflash/tiflash-spill-disk.md#query-level-spilling). The default value is `0.7`. | +| [`tikv_client_read_timeout`](/system-variables.md#tikv_client_read_timeout-new-in-v740) | Newly added | Controls the timeout for TiDB to send a TiKV RPC read request in a query. The default value `0` indicates that the default timeout (usually 40 seconds) is used. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`enable-stats-cache-mem-quota`](/tidb-configuration-file.md#enable-stats-cache-mem-quota-new-in-v610) | Modified | The default value is changed from `false` to `true`, which means the memory limit for caching TiDB statistics is enabled by default. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].periodic-compaction-seconds](/tikv-configuration-file.md#periodic-compaction-seconds-new-in-v720) | Modified | The default value is changed from `"30d"` to `"0s"` to disable periodic compaction of RocksDB by default. This change avoids a significant number of compactions being triggered after the TiDB upgrade, which affects the read and write performance of the frontend. | +| TiKV | [rocksdb.\[defaultcf\|writecf\|lockcf\].ttl](/tikv-configuration-file.md#ttl-new-in-v720) | Modified | The default value is changed from `"30d"` to `"0s"` so that SST files do not trigger compactions by default due to TTL, which avoids affecting the read and write performance of the frontend. | +| TiFlash | [`flash.compact_log_min_gap`](/tiflash/tiflash-configuration.md) | Newly added | When the gap between the `applied_index` advanced by the current Raft state machine and the `applied_index` at the last disk spilling exceeds `compact_log_min_gap`, TiFlash executes the `CompactLog` command from TiKV and spills data to disk. | +| TiFlash | [`profiles.default.enable_resource_control`](/tiflash/tiflash-configuration.md) | Newly added | Controls whether to enable the TiFlash resource control feature. | +| TiFlash | [`storage.format_version`](/tiflash/tiflash-configuration.md) | Modified | Change the default value from `4` to `5`. The new format can reduce the number of physical files by merging smaller files. | +| Dumpling | [`--csv-line-terminator`](/dumpling-overview.md#option-list-of-dumpling) | Newly added | Specifies the desired terminator of CSV files . This option supports `"\r\n"` and `"\n"`. The default value is `"\r\n"`, which is consistent with the earlier versions. | +| TiCDC | [`claim-check-storage-uri`](/ticdc/ticdc-sink-to-kafka.md#send-large-messages-to-external-storage) | Newly added | When `large-message-handle-option` is set to `claim-check`, `claim-check-storage-uri` must be set to a valid external storage address. Otherwise, creating a changefeed results in an error. | +| TiCDC | [`large-message-handle-compression`](/ticdc/ticdc-sink-to-kafka.md#ticdc-data-compression) | Newly added | Controls whether to enable compression during encoding. The default value is empty, which means not enabled. | +| TiCDC | [`large-message-handle-option`](/ticdc/ticdc-sink-to-kafka.md#send-large-messages-to-external-storage) | Modified | This configuration item adds a new value `claim-check`. When it is set to `claim-check`, TiCDC Kafka sink supports sending the message to external storage when the message size exceeds the limit and sends a message to Kafka containing the address of this large message in external storage. | + +## Deprecated and removed features + ++ [Mydumper](https://docs.pingcap.com/tidb/v4.0/mydumper-overview) will be deprecated in v7.5.0 and most of its features have been replaced by [Dumpling](/dumpling-overview.md). It is strongly recommended that you use Dumpling instead of mydumper. ++ TiKV-importer will be deprecated in v7.5.0. It is strongly recommended that you use the [Physical Import Mode of TiDB Lightning](/tidb-lightning/tidb-lightning-physical-import-mode.md) as an alternative. ++ The `enable-old-value` parameter of TiCDC is removed. [#9667](https://github.com/pingcap/tiflow/issues/9667) @[3AceShowHand](https://github.com/3AceShowHand) + +## Improvements + ++ TiDB + + - Optimize memory usage and performance for `ANALYZE` operations on partitioned tables [#47071](https://github.com/pingcap/tidb/issues/47071) [#47104](https://github.com/pingcap/tidb/issues/47104) [#46804](https://github.com/pingcap/tidb/issues/46804) @[hawkingrei](https://github.com/hawkingrei) + - Optimize memory usage and performance for statistics garbage collection [#31778](https://github.com/pingcap/tidb/issues/31778) @[winoros](https://github.com/winoros) + - Optimize the pushdown of `limit` for index merge intersections to improve query performance [#46863](https://github.com/pingcap/tidb/issues/46863) @[AilinKid](https://github.com/AilinKid) + - Improve the cost model to minimize the chances of mistakenly choosing a full table scan when `IndexLookup` involves many table retrieval tasks [#45132](https://github.com/pingcap/tidb/issues/45132) @[qw4990](https://github.com/qw4990) + - Optimize the join elimination rule to improve the query performance of `join on unique keys` [#46248](https://github.com/pingcap/tidb/issues/46248) @[fixdb](https://github.com/fixdb) + - Change the collation of multi-valued index columns to `binary` to avoid execution failure [#46717](https://github.com/pingcap/tidb/issues/46717) @[YangKeao](https://github.com/YangKeao) + ++ TiKV + + - Optimize memory usage of Resolver to prevent OOM [#15458](https://github.com/tikv/tikv/issues/15458) @[overvenus](https://github.com/overvenus) + - Eliminate LRUCache in Router objects to reduce memory usage and prevent OOM [#15430](https://github.com/tikv/tikv/issues/15430) @[Connor1996](https://github.com/Connor1996) + - Reduce memory usage of TiCDC Resolver [#15412](https://github.com/tikv/tikv/issues/15412) @[overvenus](https://github.com/overvenus) + - Reduce memory fluctuations caused by RocksDB compaction [#15324](https://github.com/tikv/tikv/issues/15324) @[overvenus](https://github.com/overvenus) + - Reduce memory consumption in the flow control module of Partitioned Raft KV [#15269](https://github.com/tikv/tikv/issues/15269) @[overvenus](https://github.com/overvenus) + - Add the backoff mechanism for the PD client in the process of connection retries, which gradually increases retry intervals during error retries to reduce PD pressure [#15428](https://github.com/tikv/tikv/issues/15428) @[nolouch](https://github.com/nolouch) + - Support dynamically adjusting `background_compaction` of RocksDB [#15424](https://github.com/tikv/tikv/issues/15424) @[glorv](https://github.com/glorv) + ++ PD + + - Optimize TSO tracing information for easier investigation of TSO-related issues [#6856](https://github.com/tikv/pd/pull/6856) @[tiancaiamao](https://github.com/tiancaiamao) + - Support reusing HTTP Client connections to reduce memory usage [#6913](https://github.com/tikv/pd/issues/6913) @[nolouch](https://github.com/nolouch) + - Improve the speed of PD automatically updating cluster status when the backup cluster is disconnected [#6883](https://github.com/tikv/pd/issues/6883) @[disksing](https://github.com/disksing) + - Enhance the configuration retrieval method of the resource control client to dynamically fetch the latest configurations [#7043](https://github.com/tikv/pd/issues/7043) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Improve write performance during random write workloads by optimizing the spilling policy of the TiFlash write process [#7564](https://github.com/pingcap/tiflash/issues/7564) @[CalvinNeo](https://github.com/CalvinNeo) + - Add more metrics about the Raft replication process for TiFlash [#8068](https://github.com/pingcap/tiflash/issues/8068) @[CalvinNeo](https://github.com/CalvinNeo) + - Reduce the number of small files to avoid potential exhaustion of file system inodes [#7595](https://github.com/pingcap/tiflash/issues/7595) @[hongyunyan](https://github.com/hongyunyan) + ++ Tools + + + Backup & Restore (BR) + + - Alleviate the issue that the latency of the PITR log backup progress increases when Region leadership migration occurs [#13638](https://github.com/tikv/tikv/issues/13638) @[YuJuncen](https://github.com/YuJuncen) + - Enhance support for connection reuse of log backup and PITR restore tasks by setting `MaxIdleConns` and `MaxIdleConnsPerHost` parameters in the HTTP client [#46011](https://github.com/pingcap/tidb/issues/46011) @[Leavrth](https://github.com/Leavrth) + - Improve fault tolerance of BR when it fails to connect to PD or external S3 storage [#42909](https://github.com/pingcap/tidb/issues/42909) @[Leavrth](https://github.com/Leavrth) + - Add a new restore parameter `WaitTiflashReady`. When this parameter is enabled, the restore operation will be completed after TiFlash replicas are successfully replicated [#43828](https://github.com/pingcap/tidb/issues/43828) [#46302](https://github.com/pingcap/tidb/issues/46302) @[3pointer](https://github.com/3pointer) + - Reduce the CPU overhead of log backup `resolve lock` [#40759](https://github.com/pingcap/tidb/issues/40759) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Optimize the execution logic of replicating the `ADD INDEX` DDL operations to avoid blocking subsequent DML statements [#9644](https://github.com/pingcap/tiflow/issues/9644) @[sdojjy](https://github.com/sdojjy) + + + TiDB Lightning + + - Optimize the retry logic of TiDB Lightning during the Region scatter phase [#46203](https://github.com/pingcap/tidb/issues/46203) @[mittalrishabh](https://github.com/mittalrishabh) + - Optimize the retry logic of TiDB Lightning for the `no leader` error during the data import phase [#46253](https://github.com/pingcap/tidb/issues/46253) @[lance6716](https://github.com/lance6716) + +## Bug fixes + ++ TiDB + + - Fix the issue that the `BatchPointGet` operator returns incorrect results for tables that are not hash partitioned [#45889](https://github.com/pingcap/tidb/issues/45889) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the `BatchPointGet` operator returns incorrect results for hash partitioned tables [#46779](https://github.com/pingcap/tidb/issues/46779) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the TiDB parser remains in a state and causes parsing failure [#45898](https://github.com/pingcap/tidb/issues/45898) @[qw4990](https://github.com/qw4990) + - Fix the issue that `EXCHANGE PARTITION` does not check constraints [#45922](https://github.com/pingcap/tidb/issues/45922) @[mjonss](https://github.com/mjonss) + - Fix the issue that the `tidb_enforce_mpp` system variable cannot be correctly restored [#46214](https://github.com/pingcap/tidb/issues/46214) @[djshow832](https://github.com/djshow832) + - Fix the issue that the `_` in the `LIKE` clause is incorrectly handled [#46287](https://github.com/pingcap/tidb/issues/46287) [#46618](https://github.com/pingcap/tidb/issues/46618) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the `schemaTs` is set to 0 when TiDB fails to obtain the schema [#46325](https://github.com/pingcap/tidb/issues/46325) @[hihihuhu](https://github.com/hihihuhu) + - Fix the issue that `Duplicate entry` might occur when `AUTO_ID_CACHE=1` is set [#46444](https://github.com/pingcap/tidb/issues/46444) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB recovers slowly after a panic when `AUTO_ID_CACHE=1` is set [#46454](https://github.com/pingcap/tidb/issues/46454) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `next_row_id` in `SHOW CREATE TABLE` is incorrect when `AUTO_ID_CACHE=1` is set [#46545](https://github.com/pingcap/tidb/issues/46545) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the panic issue that occurs during parsing when using CTE in subqueries [#45838](https://github.com/pingcap/tidb/issues/45838) @[djshow832](https://github.com/djshow832) + - Fix the issue that restrictions on partitioned tables remain on the original table when `EXCHANGE PARTITION` fails or is canceled [#45920](https://github.com/pingcap/tidb/issues/45920) [#45791](https://github.com/pingcap/tidb/issues/45791) @[mjonss](https://github.com/mjonss) + - Fix the issue that the definition of List partitions does not support using both `NULL` and empty strings [#45694](https://github.com/pingcap/tidb/issues/45694) @[mjonss](https://github.com/mjonss) + - Fix the issue of not being able to detect data that does not comply with partition definitions during partition exchange [#46492](https://github.com/pingcap/tidb/issues/46492) @[mjonss](https://github.com/mjonss) + - Fix the issue that the `tmp-storage-quota` configuration does not take effect [#45161](https://github.com/pingcap/tidb/issues/45161) [#26806](https://github.com/pingcap/tidb/issues/26806) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `WEIGHT_STRING()` function does not match the collation [#45725](https://github.com/pingcap/tidb/issues/45725) @[dveeden](https://github.com/dveeden) + - Fix the issue that an error in Index Join might cause the query to get stuck [#45716](https://github.com/pingcap/tidb/issues/45716) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the behavior is inconsistent with MySQL when comparing a `DATETIME` or `TIMESTAMP` column with a number constant [#38361](https://github.com/pingcap/tidb/issues/38361) @[yibin87](https://github.com/yibin87) + - Fix the incorrect result that occurs when comparing unsigned types with `Duration` type constants [#45410](https://github.com/pingcap/tidb/issues/45410) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that access path pruning logic ignores the `READ_FROM_STORAGE(TIFLASH[...])` hint, which causes the `Can't find a proper physical plan` error [#40146](https://github.com/pingcap/tidb/issues/40146) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `GROUP_CONCAT` cannot parse the `ORDER BY` column [#41986](https://github.com/pingcap/tidb/issues/41986) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that HashCode is repeatedly calculated for deeply nested expressions, which causes high memory usage and OOM [#42788](https://github.com/pingcap/tidb/issues/42788) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the `cast(col)=range` condition causes FullScan when CAST has no precision loss [#45199](https://github.com/pingcap/tidb/issues/45199) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that when Aggregation is pushed down through Union in MPP execution plans, the results are incorrect [#45850](https://github.com/pingcap/tidb/issues/45850) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that bindings with `in (?)` cannot match `in (?, ... ?)` [#44298](https://github.com/pingcap/tidb/issues/44298) @[qw4990](https://github.com/qw4990) + - Fix the error caused by not considering the connection collation when `non-prep plan cache` reuses the execution plan [#47008](https://github.com/pingcap/tidb/issues/47008) @[qw4990](https://github.com/qw4990) + - Fix the issue that no warning is reported when an executed plan does not hit the plan cache [#46159](https://github.com/pingcap/tidb/issues/46159) @[qw4990](https://github.com/qw4990) + - Fix the issue that `plan replayer dump explain` reports an error [#46197](https://github.com/pingcap/tidb/issues/46197) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that executing DML statements with CTE can cause panic [#46083](https://github.com/pingcap/tidb/issues/46083) @[winoros](https://github.com/winoros) + - Fix the issue that the `TIDB_INLJ` hint does not take effect when joining two sub-queries [#46160](https://github.com/pingcap/tidb/issues/46160) @[qw4990](https://github.com/qw4990) + - Fix the issue that the results of `MERGE_JOIN` are incorrect [#46580](https://github.com/pingcap/tidb/issues/46580) @[qw4990](https://github.com/qw4990) + ++ TiKV + + - Fix the issue that TiKV fails to start when Titan is enabled and the `Blob file deleted twice` error occurs [#15454](https://github.com/tikv/tikv/issues/15454) @[Connor1996](https://github.com/Connor1996) + - Fix the issue of no data in the Thread Voluntary and Thread Nonvoluntary monitoring panels [#15413](https://github.com/tikv/tikv/issues/15413) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + - Fix the data error of continuously increasing raftstore-applys [#15371](https://github.com/tikv/tikv/issues/15371) @[Connor1996](https://github.com/Connor1996) + - Fix the TiKV panic issue caused by incorrect metadata of Region [#13311](https://github.com/tikv/tikv/issues/13311) @[zyguan](https://github.com/zyguan) + - Fix the issue of QPS dropping to 0 after switching from `sync_recovery` to `sync` [#15366](https://github.com/tikv/tikv/issues/15366) @[nolouch](https://github.com/nolouch) + - Fix the issue that Online Unsafe Recovery does not abort on timeout [#15346](https://github.com/tikv/tikv/issues/15346) @[Connor1996](https://github.com/Connor1996) + - Fix the potential memory leak issue caused by CpuRecord [#15304](https://github.com/tikv/tikv/issues/15304) @[overvenus](https://github.com/overvenus) + - Fix the issue that `"Error 9002: TiKV server timeout"` occurs when the backup cluster is down and the primary cluster is queried [#12914](https://github.com/tikv/tikv/issues/12914) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that the backup TiKV gets stuck when TiKV restarts after the primary cluster recovers [#12320](https://github.com/tikv/tikv/issues/12320) @[disksing](https://github.com/disksing) + ++ PD + + - Fix the issue that the Region information is not updated and saved during Flashback [#6912](https://github.com/tikv/pd/issues/6912) @[overvenus](https://github.com/overvenus) + - Fix the issue of slow switching of PD Leaders due to slow synchronization of store config [#6918](https://github.com/tikv/pd/issues/6918) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that the groups are not considered in Scatter Peers [#6962](https://github.com/tikv/pd/issues/6962) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that RU consumption less than 0 causes PD to crash [#6973](https://github.com/tikv/pd/issues/6973) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that modified isolation levels are not synchronized to the default placement rules [#7121](https://github.com/tikv/pd/issues/7121) @[rleungx](https://github.com/rleungx) + - Fix the issue that the client-go regularly updating `min-resolved-ts` might cause PD OOM when the cluster is large [#46664](https://github.com/pingcap/tidb/issues/46664) @[HuSharp](https://github.com/HuSharp) + ++ TiFlash + + - Fix the issue that the `max_snapshot_lifetime` metric is displayed incorrectly on Grafana [#7713](https://github.com/pingcap/tiflash/issues/7713) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that some metrics about the maximum duration are not correct [#8076](https://github.com/pingcap/tiflash/issues/8076) @[CalvinNeo](https://github.com/CalvinNeo) + - Fix the issue that TiDB incorrectly reports that an MPP task has failed [#7177](https://github.com/pingcap/tiflash/issues/7177) @[yibin87](https://github.com/yibin87) + ++ Tools + + + Backup & Restore (BR) + + - Fix an issue that the misleading error message `resolve lock timeout` covers up the actual error when backup fails [#43236](https://github.com/pingcap/tidb/issues/43236) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that recovering implicit primary keys using PITR might cause conflicts [#46520](https://github.com/pingcap/tidb/issues/46520) @[3pointer](https://github.com/3pointer) + - Fix the issue that recovering meta-kv using PITR might cause errors [#46578](https://github.com/pingcap/tidb/issues/46578) @[Leavrth](https://github.com/Leavrth) + - Fix the errors in BR integration test cases [#46561](https://github.com/pingcap/tidb/issues/46561) @[purelind](https://github.com/purelind) + + + TiCDC + + - Fix the issue that TiCDC accesses the invalid old address during PD scaling up and down [#9584](https://github.com/pingcap/tiflow/issues/9584) @[fubinzh](https://github.com/fubinzh) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that changefeed fails in some scenarios [#9309](https://github.com/pingcap/tiflow/issues/9309) [#9450](https://github.com/pingcap/tiflow/issues/9450) [#9542](https://github.com/pingcap/tiflow/issues/9542) [#9685](https://github.com/pingcap/tiflow/issues/9685) @[hicqu](https://github.com/hicqu) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that replication write conflicts might occur when the unique keys for multiple rows are modified in one transaction on the upstream [#9430](https://github.com/pingcap/tiflow/issues/9430) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that a replication error occurs when multiple tables are renamed in the same DDL statement on the upstream [#9476](https://github.com/pingcap/tiflow/issues/9476) [#9488](https://github.com/pingcap/tiflow/issues/9488) @[CharlesCheung96](https://github.com/CharlesCheung96) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that Chinese characters are not validated in CSV files [#9609](https://github.com/pingcap/tiflow/issues/9609) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that upstream TiDB GC is blocked after all changefeeds are removed [#9633](https://github.com/pingcap/tiflow/issues/9633) @[sdojjy](https://github.com/sdojjy) + - Fix the issue of uneven distribution of write keys among nodes when `scale-out` is enabled [#9665](https://github.com/pingcap/tiflow/issues/9665) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that sensitive user information is recorded in the logs [#9690](https://github.com/pingcap/tiflow/issues/9690) @[sdojjy](https://github.com/sdojjy) + + + TiDB Data Migration (DM) + + - Fix the issue that DM cannot handle conflicts correctly with case-insensitive collations [#9489](https://github.com/pingcap/tiflow/issues/9489) @[hihihuhu](https://github.com/hihihuhu) + - Fix the DM validator deadlock issue and enhance retries [#9257](https://github.com/pingcap/tiflow/issues/9257) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that replication lag returned by DM keeps growing when a failed DDL is skipped and no subsequent DDLs are executed [#9605](https://github.com/pingcap/tiflow/issues/9605) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that DM cannot properly track upstream table schemas when skipping online DDLs [#9587](https://github.com/pingcap/tiflow/issues/9587) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that DM skips all DMLs when resuming a task in optimistic mode [#9588](https://github.com/pingcap/tiflow/issues/9588) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that DM skips partition DDLs in optimistic mode [#9788](https://github.com/pingcap/tiflow/issues/9788) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Fix the issue that inserting data returns an error after TiDB Lightning imports the `NONCLUSTERED auto_increment` and `AUTO_ID_CACHE=1` tables [#46100](https://github.com/pingcap/tidb/issues/46100) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that checksum still reports errors when `checksum = "optional"` [#45382](https://github.com/pingcap/tidb/issues/45382) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that data import fails when the PD cluster address changes [#43436](https://github.com/pingcap/tidb/issues/43436) @[lichunzhu](https://github.com/lichunzhu) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [aidendou](https://github.com/aidendou) +- [coderplay](https://github.com/coderplay) +- [fatelei](https://github.com/fatelei) +- [highpon](https://github.com/highpon) +- [hihihuhu](https://github.com/hihihuhu) (First-time contributor) +- [isabella0428](https://github.com/isabella0428) +- [jiyfhust](https://github.com/jiyfhust) +- [JK1Zhang](https://github.com/JK1Zhang) +- [joker53-1](https://github.com/joker53-1) (First-time contributor) +- [L-maple](https://github.com/L-maple) +- [mittalrishabh](https://github.com/mittalrishabh) +- [paveyry](https://github.com/paveyry) +- [shawn0915](https://github.com/shawn0915) +- [tedyu](https://github.com/tedyu) +- [yumchina](https://github.com/yumchina) +- [ZzzhHe](https://github.com/ZzzhHe) diff --git a/releases/release-7.5.0.md b/releases/release-7.5.0.md new file mode 100644 index 0000000000000..8cd08d6776f7b --- /dev/null +++ b/releases/release-7.5.0.md @@ -0,0 +1,305 @@ +--- +title: TiDB 7.5.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 7.5.0. +--- + +# TiDB 7.5.0 Release Notes + +Release date: December 1, 2023 + +TiDB version: 7.5.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.5/production-deployment-using-tiup) + +TiDB 7.5.0 is a Long-Term Support Release (LTS). + +Compared with the previous LTS 7.1.0, 7.5.0 includes new features, improvements, and bug fixes released in [7.2.0-DMR](/releases/release-7.2.0.md), [7.3.0-DMR](/releases/release-7.3.0.md), and [7.4.0-DMR](/releases/release-7.4.0.md). When you upgrade from 7.1.x to 7.5.0, you can download the [TiDB Release Notes PDF](https://download.pingcap.org/tidb-v7.2-to-v7.5-en-release-notes.pdf) to view all release notes between the two LTS versions. The following table lists some highlights from 7.2.0 to 7.5.0: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeatureDescription
Scalability and PerformanceSupport running multiple ADD INDEX statements in parallelThis feature allows for concurrent jobs to add multiple indexes for a single table. Previously, it would take the time of X plus the time of Y to execute two ADD INDEX statements simultaneously (X and Y). With this feature, adding two indexes X and Y in one SQL can be concurrently executed, and the total execution time of DDL is significantly reduced. Especially in scenarios with wide tables, internal test data shows that performance can be improved by up to 94%.
Reliability and AvailabilityOptimize Global Sort (experimental, introduced in v7.4.0)TiDB v7.1.0 introduced the Distributed eXecution Framework (DXF). For tasks that take advantage of this framework, v7.4 introduces global sorting to eliminate the unnecessary I/O, CPU, and memory spikes caused by temporarily out-of-order data during data re-organization tasks. The global sorting takes advantage of external shared object storage (Amazon S3 in this first iteration) to store intermediary files during the job, adding flexibility and cost savings. Operations like ADD INDEX and IMPORT INTO will be faster, more resilient, more stable, more flexible, and cost less to run.
Resource control for background tasks (experimental, introduced in v7.4.0)In v7.1.0, the Resource Control feature was introduced to mitigate resource and storage access interference between workloads. TiDB v7.4.0 applied this control to the priority of background tasks as well. In v7.4.0, Resource Control now identifies and manages the priority of background task execution, such as auto-analyze, Backup & Restore, bulk load with TiDB Lightning, and online DDL. In future releases, this control will eventually apply to all background tasks.
Resource control for managing runaway queries (experimental, introduced in v7.2.0)Resource Control is a framework for resource-isolating workloads by Resource Groups, but it makes no calls on how individual queries affect work inside of each group. TiDB v7.2.0 introduces "runaway queries control" to let you control how TiDB identifies and treats these queries per Resource Group. Depending on needs, long running queries might be terminated or throttled, and the queries can be identified by exact SQL text, SQL digests or their plan digests, for better generalization. In v7.3.0, TiDB enables you to proactively watch for known bad queries, similar to a SQL blocklist at the database level.
SQLMySQL 8.0 compatibility (introduced in v7.4.0)In MySQL 8.0, the default character set is utf8mb4, and the default collation of utf8mb4 is utf8mb4_0900_ai_ci. TiDB v7.4.0 adding support for this enhances compatibility with MySQL 8.0 so that migrations and replications from MySQL 8.0 databases with the default collation are now much smoother.
DB Operations and ObservabilityTiDB Lightning's physical import mode integrated into TiDB with IMPORT INTO (GA)Before v7.2.0, to import data based on the file system, you needed to install TiDB Lightning and used its physical import mode. Now, the same capability is integrated into the IMPORT INTO statement so you can use this statement to quickly import data without installing any additional tool. This statement also supports the Distributed eXecution Framework (DXF) for parallel import, which improves import efficiency during large-scale imports.
Specify the respective TiDB nodes to execute the ADD INDEX and IMPORT INTO SQL statements (GA)You have the flexibility to specify whether to execute ADD INDEX or IMPORT INTO SQL statements on some of the existing TiDB nodes or newly added TiDB nodes. This approach enables resource isolation from the rest of the TiDB nodes, preventing any impact on business operations while ensuring optimal performance for executing the preceding SQL statements. In v7.5.0, this feature becomes generally available (GA).
DDL supports pause and resume operations (GA)Adding indexes can be big resource consumers and can affect online traffic. Even when throttled in a Resource Group or isolated to labeled nodes, there may still be a need to suspend these jobs in emergencies. As of v7.2.0, TiDB now natively supports suspending any number of these background jobs at once, freeing up needed resources while avoiding having to cancel and restart the jobs.
TiDB Dashboard supports heap profiling for TiKVPreviously, addressing TiKV OOM or high memory usage issues typically required manual execution of jeprof to generate a heap profile in the instance environment. Starting from v7.5.0, TiKV enables remote processing of heap profiles. You can now directly access the flame graph and call graph of heap profile. This feature provides the same simple and easy-to-use experience as Go heap profiling.
+ +## Feature details + +### Scalability + +* Support designating and isolating TiDB nodes to distributedly execute `ADD INDEX` or `IMPORT INTO` tasks when the Distributed eXecution Framework (DXF) is enabled [#46258](https://github.com/pingcap/tidb/issues/46258) @[ywqzzy](https://github.com/ywqzzy) + + Executing `ADD INDEX` or `IMPORT INTO` tasks in parallel in a resource-intensive cluster can consume a large amount of TiDB node resources, which can lead to cluster performance degradation. To avoid performance impact on existing services, v7.4.0 introduces the system variable [`tidb_service_scope`](/system-variables.md#tidb_service_scope-new-in-v740) as an experimental feature to control the service scope of each TiDB node under the [TiDB Distributed eXecution Framework (DXF)](/tidb-distributed-execution-framework.md). You can select several existing TiDB nodes or set the TiDB service scope for new TiDB nodes, and all distributedly executed `ADD INDEX` and `IMPORT INTO` tasks only run on these nodes. In v7.5.0, this feature becomes generally available (GA). + + For more information, see [documentation](/system-variables.md#tidb_service_scope-new-in-v740). + +### Performance + +* The TiDB Distributed eXecution Framework (DXF) becomes generally available (GA), improving the performance and stability of `ADD INDEX` and `IMPORT INTO` tasks in parallel execution [#45719](https://github.com/pingcap/tidb/issues/45719) @[wjhuang2016](https://github.com/wjhuang2016) + + The DXF introduced in v7.1.0 has become GA. In versions before TiDB v7.1.0, only one TiDB node can execute DDL tasks at the same time. Starting from v7.1.0, multiple TiDB nodes can execute the same DDL task in parallel under the DXF. Starting from v7.2.0, the DXF supports multiple TiDB nodes to execute the same `IMPORT INTO` task in parallel, thereby better utilizing the resources of the TiDB cluster and significantly improving the performance of DDL and `IMPORT INTO` tasks. In addition, you can also increase TiDB nodes to linearly improve the performance of these tasks. + + To use the DXF, set [`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710) value to `ON`. + + ```sql + SET GLOBAL tidb_enable_dist_task = ON; + ``` + + For more information, see [documentation](/tidb-global-sort.md). + +* Improve the performance of adding multiple indexes in a single SQL statement [#41602](https://github.com/pingcap/tidb/issues/41602) @[tangenta](https://github.com/tangenta) + + Before v7.5.0, when you add multiple indexes (`ADD INDEX`) in a single SQL statement, the performance was similar to adding multiple indexes using separate SQL statements. Starting from v7.5.0, the performance of adding multiple indexes in a single SQL statement is significantly improved. Especially in scenarios with wide tables, internal test data shows that performance can be improved by up to 94%. + +### DB operations + +* DDL jobs support pause and resume operations (GA) [#18015](https://github.com/pingcap/tidb/issues/18015) @[godouxm](https://github.com/godouxm) + + The pause and resume operations for DDL jobs introduced in v7.2.0 become generally available (GA). These operations let you pause resource-intensive DDL jobs (such as creating indexes) to save resources and minimize the impact on online traffic. When resources permit, you can seamlessly resume DDL jobs without canceling and restarting them. This feature improves resource utilization, enhances user experience, and simplifies the schema change process. + + You can pause and resume multiple DDL jobs using `ADMIN PAUSE DDL JOBS` or `ADMIN RESUME DDL JOBS`: + + ```sql + ADMIN PAUSE DDL JOBS 1,2; + ADMIN RESUME DDL JOBS 1,2; + ``` + + For more information, see [documentation](/ddl-introduction.md#ddl-related-commands). + +* BR supports backing up and restoring statistics [#48008](https://github.com/pingcap/tidb/issues/48008) @[Leavrth](https://github.com/Leavrth) + + Starting from TiDB v7.5.0, the br command-line tool introduces the `--ignore-stats` parameter to back up and restore database statistics. When you set this parameter to `false`, the br command-line tool supports backing up and restoring statistics of columns, indexes, and tables. In this case, you do not need to manually run the statistics collection task for the TiDB database restored from the backup, or wait for the completion of automatic collection tasks. This feature simplifies database maintenance work and improves query performance. + + For more information, see [documentation](/br/br-snapshot-manual.md#back-up-statistics). + +### Observability + +* TiDB Dashboard supports heap profiling for TiKV [#15927](https://github.com/tikv/tikv/issues/15927) @[Connor1996](https://github.com/Connor1996) + + Previously, addressing TiKV OOM or high memory usage issues typically required manual execution of `jeprof` to generate a heap profile in the instance environment. Starting from v7.5.0, TiKV enables remote processing of heap profiles. You can now directly access the flame graph and call graph of heap profile. This feature provides the same simple and easy-to-use experience as Go heap profiling. + + For more information, see [documentation](/dashboard/dashboard-profiling.md). + +### Data migration + +* Support the `IMPORT INTO` SQL statement (GA) [#46704](https://github.com/pingcap/tidb/issues/46704) @[D3Hunter](https://github.com/D3Hunter) + + In v7.5.0, the `IMPORT INTO` SQL statement becomes generally available (GA). This statement integrates the [Physical Import Mode](/tidb-lightning/tidb-lightning-physical-import-mode.md) capability of TiDB Lightning and allows you to quickly import data in formats such as CSV, SQL, and PARQUET into an empty table in TiDB. This import method eliminates the need for a separate deployment and management of TiDB Lightning, thereby reducing the complexity of data import and greatly improving import efficiency. + + For more information, see [documentation](/sql-statements/sql-statement-import-into.md). + +* Data Migration (DM) supports blocking incompatible (data-consistency-corrupting) DDL changes [#9692](https://github.com/pingcap/tiflow/issues/9692) @[GMHDBJD](https://github.com/GMHDBJD) + + Before v7.5.0, the DM Binlog Filter feature can only migrate or filter specified events, and the granularity is relatively coarse. For example, it can only filter large granularity of DDL events such as `ALTER`. This method is limited in some scenarios. For example, the application allows `ADD COLUMN` but not `DROP COLUMN`, but they are both filtered by `ALTER` events in the earlier DM versions. + + To address such issues, v7.5.0 refines the granularity of the supported DDL events, such as support filtering `MODIFY COLUMN` (modify the column data type), `DROP COLUMN`, and other fine-grained DDL events that lead to data loss, truncation of data, and loss of precision. You can configure it as needed. This feature also supports blocking incompatible DDL changes and reporting errors for such changes, so that you can intervene manually in time to avoid impacting downstream application data. + + For more information, see [documentation](/dm/dm-binlog-event-filter.md#parameter-descriptions). + +* Support real-time checkpoint updates for continuous data validation [#8463](https://github.com/pingcap/tiflow/issues/8463) @[lichunzhu](https://github.com/lichunzhu) + + Before v7.5.0, the [continuous data validation feature](/dm/dm-continuous-data-validation.md) ensures the data consistency during replication from DM to downstream. This serves as the basis for cutting over business traffic from the upstream database to TiDB. However, due to various factors such as replication delay and waiting for re-validation of inconsistent data, the continuous validation checkpoint must be refreshed every few minutes. This is unacceptable for some business scenarios where the cutover time is limited to tens of seconds. + + With the introduction of real-time updating of checkpoint for continuous data validation, you can now provide the binlog position from the upstream database. Once the continuous validation program detects this binlog position in memory, it immediately refreshes the checkpoint instead of refreshing it every few minutes. Therefore, you can quickly perform cut-off operations based on this immediately updated checkpoint. + + For more information, see [documentation](/dm/dm-continuous-data-validation.md#set-the-cutover-point-for-continuous-data-validation). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v7.4.0 to the current version (v7.5.0). If you are upgrading from v7.3.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_enable_fast_analyze`](/system-variables.md#tidb_enable_fast_analyze) | Deprecated | Controls whether to enable the statistics `Fast Analyze` feature. This feature is deprecated in v7.5.0. | +| [`tidb_analyze_partition_concurrency`](/system-variables.md#tidb_analyze_partition_concurrency) | Modified | Changes the default value from `1` to `2` after further tests. | +| [`tidb_build_stats_concurrency`](/system-variables.md#tidb_build_stats_concurrency) | Modified | Changes the default value from `4` to `2` after further tests. | +| [`tidb_merge_partition_stats_concurrency`](/system-variables.md#tidb_merge_partition_stats_concurrency) | Modified | This system variable takes effect starting from v7.5.0. It specifies the concurrency of merging statistics for a partitioned table when TiDB analyzes the partitioned table. | +| [`tidb_build_sampling_stats_concurrency`](/system-variables.md#tidb_build_sampling_stats_concurrency-new-in-v750) | Newly added | Controls the sampling concurrency of the `ANALYZE` process. | +| [`tidb_enable_async_merge_global_stats`](/system-variables.md#tidb_enable_async_merge_global_stats-new-in-v750) | Newly added | This variable is used by TiDB to merge statistics asynchronously to avoid OOM issues. | +| [`tidb_gogc_tuner_max_value`](/system-variables.md#tidb_gogc_tuner_max_value-new-in-v750) | Newly added | Controls the maximum value of GOGC that the GOGC Tuner can adjust. | +| [`tidb_gogc_tuner_min_value`](/system-variables.md#tidb_gogc_tuner_min_value-new-in-v750) | Newly added | Controls the minimum value of GOGC that the GOGC Tuner can adjust.| + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`tikv-client.copr-req-timeout`](/tidb-configuration-file.md#copr-req-timeout-new-in-v750) | Newly added | Sets the timeout of a single Coprocessor request. | +| TiKV | [`raftstore.inspect-interval`](/tikv-configuration-file.md#inspect-interval) | Modified | Changes the default value from `500ms` to `100ms` after optimizing the algorithm to improve the sensitivity of slow node detection. | +| TiKV | [`raftstore.region-compact-min-redundant-rows`](/tikv-configuration-file.md#region-compact-min-redundant-rows-new-in-v710) | Modified | Sets the number of redundant MVCC rows required to trigger RocksDB compaction. Starting from v7.5.0, this configuration item takes effect for the `"raft-kv"` storage engine. | +| TiKV | [`raftstore.region-compact-redundant-rows-percent`](/tikv-configuration-file.md#region-compact-redundant-rows-percent-new-in-v710) | Modified | Sets the percentage of redundant MVCC rows required to trigger RocksDB compaction. Starting from v7.5.0, this configuration item takes effect for the `"raft-kv"` storage engine. | +| TiKV | [`raftstore.evict-cache-on-memory-ratio`](/tikv-configuration-file.md#evict-cache-on-memory-ratio-new-in-v750) | Newly added | When the memory usage of TiKV exceeds 90% of the system available memory, and the memory occupied by Raft entry cache exceeds the `evict-cache-on-memory-ratio` of used memory, TiKV evicts the Raft entry cache. | +| TiKV | [`memory.enable-heap-profiling`](/tikv-configuration-file.md#enable-heap-profiling-new-in-v750) | Newly added | Controls whether to enable Heap Profiling to track the memory usage of TiKV. | +| TiKV | [`memory.profiling-sample-per-bytes`](/tikv-configuration-file.md#profiling-sample-per-bytes-new-in-v750) | Newly added | Specifies the amount of data sampled by Heap Profiling each time, rounding up to the nearest power of 2. | +| BR | [`--ignore-stats`](/br/br-snapshot-manual.md#back-up-statistics) | Newly added | Controls whether to back up and restore database statistics. When you set this parameter to `false`, the br command-line tool supports backing up and restoring statistics of columns, indexes, and tables. | +| TiCDC | [`case-sensitive`](/ticdc/ticdc-changefeed-config.md) | Modified | Changes the default value from `true` to `false` after further tests, which means that the table names and database names in the TiCDC configuration file are case-insensitive by default. | +| TiCDC | [`sink.dispatchers.partition`](/ticdc/ticdc-changefeed-config.md) | Modified | Controls how TiCDC dispatches incremental data to Kafka partitions. v7.5.0 introduces a new value option `columns`, which uses the explicitly specified column values to calculate the partition number. | +| TiCDC | [`changefeed-error-stuck-duration`](/ticdc/ticdc-changefeed-config.md) | Newly added | Controls the duration for which the changefeed is allowed to automatically retry when internal errors or exceptions occur. | +| TiCDC | [`encoding-worker-num`](/ticdc/ticdc-changefeed-config.md) | Newly added | Controls the number of encoding and decoding workers in the redo module. | +| TiCDC | [`flush-worker-num`](/ticdc/ticdc-changefeed-config.md) | Newly added | Controls the number of flushing workers in the redo module. | +| TiCDC | [`sink.column-selectors`](/ticdc/ticdc-changefeed-config.md) | Newly added | Controls the specified columns of data change events that TiCDC sends to Kafka when dispatching incremental data. | +| TiCDC | [`sql-mode`](/ticdc/ticdc-changefeed-config.md) | Newly added | Specifies the SQL mode used by TiCDC when parsing DDL statements. The default value is the same as the default SQL mode of TiDB. | +| TiDB Lightning | `--importer` | Deleted | Specifies the address of TiKV-importer, which is deprecated in v7.5.0. | + +## Offline package changes + +Starting from v7.5.0, the following contents are removed from the `TiDB-community-toolkit` [binary package](/binary-package.md): + +- `tikv-importer-{version}-linux-{arch}.tar.gz` +- `mydumper` +- `spark-{version}-any-any.tar.gz` +- `tispark-{version}-any-any.tar.gz` + +## Deprecated features + +* [Mydumper](https://docs.pingcap.com/tidb/v4.0/mydumper-overview) is deprecated in v7.5.0 and most of its features have been replaced by [Dumpling](/dumpling-overview.md). It is strongly recommended that you use Dumpling instead of Mydumper. + +* TiKV-importer is deprecated in v7.5.0. It is strongly recommended that you use the [Physical Import Mode of TiDB Lightning](/tidb-lightning/tidb-lightning-physical-import-mode.md) as an alternative. + +* Starting from TiDB v7.5.0, technical support for the data replication feature of [TiDB Binlog](/tidb-binlog/tidb-binlog-overview.md) is no longer provided. It is strongly recommended to use [TiCDC](/ticdc/ticdc-overview.md) as an alternative solution for data replication. Although TiDB Binlog v7.5.0 still supports the Point-in-Time Recovery (PITR) scenario, this component will be completely deprecated in future versions. It is recommended to use [PITR](/br/br-pitr-guide.md) as an alternative solution for data recovery. + +* The [`Fast Analyze`](/system-variables.md#tidb_enable_fast_analyze) feature (experimental) for statistics is deprecated in v7.5.0. + +* The [incremental collection](https://docs.pingcap.com/tidb/v7.4/statistics#incremental-collection) feature (experimental) for statistics is deprecated in v7.5.0. + +## Improvements + ++ TiDB + + - Optimize the concurrency model of merging GlobalStats: introduce [`tidb_enable_async_merge_global_stats`](/system-variables.md#tidb_enable_async_merge_global_stats-new-in-v750) to enable simultaneous loading and merging of statistics, which speeds up the generation of GlobalStats on partitioned tables. Optimize the memory usage of merging GlobalStats to avoid OOM and reduce memory allocations. [#47219](https://github.com/pingcap/tidb/issues/47219) @[hawkingrei](https://github.com/hawkingrei) + - Optimize the `ANALYZE` process: introduce [`tidb_build_sampling_stats_concurrency`](/system-variables.md#tidb_build_sampling_stats_concurrency-new-in-v750) to better control the `ANALYZE` concurrency to reduce resource consumption. Optimize the memory usage of `ANALYZE` to reduce memory allocation and avoid frequent GC by reusing some intermediate results. [#47275](https://github.com/pingcap/tidb/issues/47275) @[hawkingrei](https://github.com/hawkingrei) + - Optimize the use of placement policies: support configuring the range of a policy to global and improve the syntax support for common scenarios. [#45384](https://github.com/pingcap/tidb/issues/45384) @[nolouch](https://github.com/nolouch) + - Improve the performance of adding indexes with `tidb_ddl_enable_fast_reorg` enabled. In internal tests, v7.5.0 improves the performance by up to 62.5% compared with v6.5.0. [#47757](https://github.com/pingcap/tidb/issues/47757) @[tangenta](https://github.com/tangenta) + ++ TiKV + + - Avoid holding mutex when writing Titan manifest files to prevent affecting other threads [#15351](https://github.com/tikv/tikv/issues/15351) @[Connor1996](https://github.com/Connor1996) + ++ PD + + - Improve the stability and usability of the `evict-slow-trend` scheduler [#7156](https://github.com/tikv/pd/issues/7156) @[LykxSassinato](https://github.com/LykxSassinator) + ++ Tools + + + Backup & Restore (BR) + + - Add a new inter-table backup parameter `table-concurrency` for snapshot backups. This parameter is used to control the inter-table concurrency of meta information such as statistics backup and data validation [#48571](https://github.com/pingcap/tidb/issues/48571) @[3pointer](https://github.com/3pointer) + - During restoring a snapshot backup, BR retries when it encounters certain network errors [#48528](https://github.com/pingcap/tidb/issues/48528) @[Leavrth](https://github.com/Leavrth) + +## Bug fixes + ++ TiDB + + - Prohibit split table operations on non-integer clustered indexes [#47350](https://github.com/pingcap/tidb/issues/47350) @[tangenta](https://github.com/tangenta) + - Fix the issue of encoding time fields with incorrect timezone information [#46033](https://github.com/pingcap/tidb/issues/46033) @[tangenta](https://github.com/tangenta) + - Fix the issue that the Sort operator might cause TiDB to crash during the spill process [#47538](https://github.com/pingcap/tidb/issues/47538) @[windtalker](https://github.com/windtalker) + - Fix the issue that TiDB returns `Can't find column` for queries with `GROUP_CONCAT` [#41957](https://github.com/pingcap/tidb/issues/41957) @[AilinKid](https://github.com/AilinKid) + - Fix the panic issue of `batch-client` in `client-go` [#47691](https://github.com/pingcap/tidb/issues/47691) @[crazycs520](https://github.com/crazycs520) + - Fix the issue of incorrect memory usage estimation in `INDEX_LOOKUP_HASH_JOIN` [#47788](https://github.com/pingcap/tidb/issues/47788) @[SeaRise](https://github.com/SeaRise) + - Fix the issue of uneven workload caused by the rejoining of a TiFlash node that has been offline for a long time [#35418](https://github.com/pingcap/tidb/issues/35418) @[windtalker](https://github.com/windtalker) + - Fix the issue that the chunk cannot be reused when the HashJoin operator performs probe [#48082](https://github.com/pingcap/tidb/issues/48082) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `COALESCE()` function returns incorrect result type for `DATE` type parameters [#46475](https://github.com/pingcap/tidb/issues/46475) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that `UPDATE` statements with subqueries are incorrectly converted to PointGet [#48171](https://github.com/pingcap/tidb/issues/48171) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that incorrect results are returned when the cached execution plans contain the comparison between date types and `unix_timestamp` [#48165](https://github.com/pingcap/tidb/issues/48165) @[qw4990](https://github.com/qw4990) + - Fix the issue that an error is reported when default inline common table expressions (CTEs) with aggregate functions or window functions are referenced by recursive CTEs [#47881](https://github.com/pingcap/tidb/issues/47881) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that the optimizer mistakenly selects IndexFullScan to reduce sort introduced by window functions [#46177](https://github.com/pingcap/tidb/issues/46177) @[qw4990](https://github.com/qw4990) + - Fix the issue that multiple references to CTEs result in incorrect results due to condition pushdown of CTEs [#47881](https://github.com/pingcap/tidb/issues/47881) @[winoros](https://github.com/winoros) + - Fix the issue that the MySQL compression protocol cannot handle large loads of data (>=16M) [#47152](https://github.com/pingcap/tidb/issues/47152) [#47157](https://github.com/pingcap/tidb/issues/47157) [#47161](https://github.com/pingcap/tidb/issues/47161) @[dveeden](https://github.com/dveeden) + - Fix the issue that TiDB does not read `cgroup` resource limits when it is started with `systemd` [#47442](https://github.com/pingcap/tidb/issues/47442) @[hawkingrei](https://github.com/hawkingrei) + ++ TiKV + + - Fix the issue that retrying prewrite requests in the pessimistic transaction mode might cause the risk of data inconsistency in rare cases [#11187](https://github.com/tikv/tikv/issues/11187) @[MyonKeminta](https://github.com/MyonKeminta) + ++ PD + + - Fix the issue that `evict-leader-scheduler` might lose configuration [#6897](https://github.com/tikv/pd/issues/6897) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that after a store goes offline, the monitoring metric of its statistics is not deleted [#7180](https://github.com/tikv/pd/issues/7180) @[rleungx](https://github.com/rleungx) + - Fix the issue that `canSync` and `hasMajority` might be calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode when the configuration of Placement Rules is complex [#7201](https://github.com/tikv/pd/issues/7201) @[disksing](https://github.com/disksing) + - Fix the issue that the rule checker does not add Learners according to the configuration of Placement Rules [#7185](https://github.com/tikv/pd/issues/7185) @[nolouch](https://github.com/nolouch) + - Fix the issue that TiDB Dashboard cannot read PD `trace` data correctly [#7253](https://github.com/tikv/pd/issues/7253) @[nolouch](https://github.com/nolouch) + - Fix the issue that PD might panic due to empty Regions obtained internally [#7261](https://github.com/tikv/pd/issues/7261) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that `available_stores` is calculated incorrectly for clusters adopting the Data Replication Auto Synchronous (DR Auto-Sync) mode [#7221](https://github.com/tikv/pd/issues/7221) @[disksing](https://github.com/disksing) + - Fix the issue that PD might delete normal Peers when TiKV nodes are unavailable [#7249](https://github.com/tikv/pd/issues/7249) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that adding multiple TiKV nodes to a large cluster might cause TiKV heartbeat reporting to become slow or stuck [#7248](https://github.com/tikv/pd/issues/7248) @[rleungx](https://github.com/rleungx) + ++ TiFlash + + - Fix the issue that the `UPPER()` and `LOWER()` functions return inconsistent results between TiDB and TiFlash [#7695](https://github.com/pingcap/tiflash/issues/7695) @[windtalker](https://github.com/windtalker) + - Fix the issue that executing queries on empty partitions causes query failure [#8220](https://github.com/pingcap/tiflash/issues/8220) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the panic issue caused by table creation failure when replicating TiFlash replicas [#8217](https://github.com/pingcap/tiflash/issues/8217) @[hongyunyan](https://github.com/hongyunyan) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that PITR might skip restoring the `CREATE INDEX` DDL statement [#47482](https://github.com/pingcap/tidb/issues/47482) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the log backup might get stuck in some scenarios when backing up large wide tables [#15714](https://github.com/tikv/tikv/issues/15714) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the performance issue caused by accessing NFS directories when replicating data to an object store sink [#10041](https://github.com/pingcap/tiflow/issues/10041) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the storage path is misspelled when `claim-check` is enabled [#10036](https://github.com/pingcap/tiflow/issues/10036) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that TiCDC scheduling is not balanced in some cases [#9845](https://github.com/pingcap/tiflow/issues/9845) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that TiCDC might get stuck when replicating data to Kafka [#9855](https://github.com/pingcap/tiflow/issues/9855) @[hicqu](https://github.com/hicqu) + - Fix the issue that the TiCDC processor might panic in some cases [#9849](https://github.com/pingcap/tiflow/issues/9849) [#9915](https://github.com/pingcap/tiflow/issues/9915) @[hicqu](https://github.com/hicqu) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that enabling `kv-client.enable-multiplexing` causes replication tasks to get stuck [#9673](https://github.com/pingcap/tiflow/issues/9673) @[fubinzh](https://github.com/fubinzh) + - Fix the issue that an owner node gets stuck due to NFS failure when the redo log is enabled [#9886](https://github.com/pingcap/tiflow/issues/9886) @[3AceShowHand](https://github.com/3AceShowHand) + +## Performance test + +To learn about the performance of TiDB v7.5.0, you can refer to the [TPC-C performance test report](https://docs.pingcap.com/tidbcloud/v7.5.0-performance-benchmarking-with-tpcc) and [Sysbench performance test report](https://docs.pingcap.com/tidbcloud/v7.5.0-performance-benchmarking-with-sysbench) of the TiDB Dedicated cluster. + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [jgrande](https://github.com/jgrande) (First-time contributor) +- [shawn0915](https://github.com/shawn0915) diff --git a/releases/release-7.5.1.md b/releases/release-7.5.1.md new file mode 100644 index 0000000000000..e519214530e67 --- /dev/null +++ b/releases/release-7.5.1.md @@ -0,0 +1,232 @@ +--- +title: TiDB 7.5.1 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.5.1. +--- + +# TiDB 7.5.1 Release Notes + +Release date: February 29, 2024 + +TiDB version: 7.5.1 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.5/production-deployment-using-tiup) + +## Compatibility changes + +- Prohibit setting [`require_secure_transport`](https://docs.pingcap.com/tidb/v7.5/system-variables#require_secure_transport-new-in-v610) to `ON` in Security Enhanced Mode (SEM) to prevent potential connectivity issues for users [#47665](https://github.com/pingcap/tidb/issues/47665) @[tiancaiamao](https://github.com/tiancaiamao) +- To reduce the overhead of log printing, TiFlash changes the default value of `logger.level` from `"debug"` to `"info"` [#8641](https://github.com/pingcap/tiflash/issues/8641) @[JaySon-Huang](https://github.com/JaySon-Huang) +- Introduce the TiKV configuration item [`gc.num-threads`](https://docs.pingcap.com/tidb/v7.5/tikv-configuration-file#num-threads-new-in-v658-and-v751) to set the number of GC threads when `enable-compaction-filter` is `false` [#16101](https://github.com/tikv/tikv/issues/16101) @[tonyxuqqi](https://github.com/tonyxuqqi) +- TiCDC Changefeed introduces the following new configuration items: + - [`compression`](/ticdc/ticdc-changefeed-config.md): enables you to configure the compression behavior of redo log files [#10176](https://github.com/pingcap/tiflow/issues/10176) @[sdojjy](https://github.com/sdojjy) + - [`sink.cloud-storage-config`](/ticdc/ticdc-changefeed-config.md): enables you to set the automatic cleanup of historical data when replicating data to object storage [#10109](https://github.com/pingcap/tiflow/issues/10109) @[CharlesCheung96](https://github.com/CharlesCheung96) + - [`consistent.flush-concurrency`](/ticdc/ticdc-changefeed-config.md): enables you to set the concurrency for uploading a single redo file [#10226](https://github.com/pingcap/tiflow/issues/10226) @[sdojjy](https://github.com/sdojjy) + +## Improvements + ++ TiDB + + - Use `tikv_client_read_timeout` during the DDL schema reload process to reduce the impact of Meta Region Leader read unavailability on the cluster [#48124](https://github.com/pingcap/tidb/issues/48124) @[cfzjywxk](https://github.com/cfzjywxk) + - Enhance observability related to resource control [#49318](https://github.com/pingcap/tidb/issues/49318) @[glorv](https://github.com/glorv) @[bufferflies](https://github.com/bufferflies) @[nolouch](https://github.com/nolouch) + + As more and more users use resource groups to isolate application workloads, Resource Control provides enhanced data based on resource groups. This helps you monitor resource group workloads and settings, ensuring that you can quickly identify and accurately diagnose problems, including: + + - [Slow Queries](/identify-slow-queries.md): add the resource group name, resource unit (RU) consumption, and time for waiting for resources. + - [Statement Summary Tables](/statement-summary-tables.md): add the resource group name, RU consumption, and time for waiting for resources. + - In the system variable [`tidb_last_query_info`](/system-variables.md#tidb_last_query_info-new-in-v4014), add a new entry `ru_consumption` to indicate the consumed [RU](/tidb-resource-control.md#what-is-request-unit-ru) by SQL statements. You can use this variable to get the resource consumption of the last statement in the session. + - Add database metrics based on resource groups: QPS/TPS, execution time (P999/P99/P95), number of failures, and number of connections. + + - Modify the `CANCEL IMPORT JOB` statement to a synchronous statement [#48736](https://github.com/pingcap/tidb/issues/48736) @[D3Hunter](https://github.com/D3Hunter) + - Support the [`FLASHBACK CLUSTER TO TSO`](https://docs.pingcap.com/tidb/v7.5/sql-statement-flashback-cluster) syntax [#48372](https://github.com/pingcap/tidb/issues/48372) @[BornChanger](https://github.com/BornChanger) + - Optimize the TiDB implementation when handling some type conversions and fix related issues [#47945](https://github.com/pingcap/tidb/issues/47945) [#47864](https://github.com/pingcap/tidb/issues/47864) [#47829](https://github.com/pingcap/tidb/issues/47829) [#47816](https://github.com/pingcap/tidb/issues/47816) @[YangKeao](https://github.com/YangKeao) @[lcwangchao](https://github.com/lcwangchao) + - When a non-binary collation is set and the query includes `LIKE`, the optimizer generates an `IndexRangeScan` to improve the execution efficiency [#48181](https://github.com/pingcap/tidb/issues/48181) [#49138](https://github.com/pingcap/tidb/issues/49138) @[time-and-fate](https://github.com/time-and-fate) + - Enhance the ability to convert `OUTER JOIN` to `INNER JOIN` in specific scenarios [#49616](https://github.com/pingcap/tidb/issues/49616) @[qw4990](https://github.com/qw4990) + - Support multiple accelerated `ADD INDEX` DDL tasks to be queued for execution, instead of falling back to normal `ADD INDEX` tasks [#47758](https://github.com/pingcap/tidb/issues/47758) @[tangenta](https://github.com/tangenta) + - Improve the speed of adding indexes to empty tables [#49682](https://github.com/pingcap/tidb/issues/49682) @[zimulala](https://github.com/zimulala) + ++ TiKV + + - Enhance the slow store detection algorithm by improving its sensitivity and reducing the false-positive rate, especially in intensive read and write load scenarios [#15909](https://github.com/tikv/tikv/issues/15909) @[LykxSassinator](https://github.com/LykxSassinator) + ++ TiFlash + + - Improve the calculation method for [Request Unit (RU)](/tidb-resource-control.md#what-is-request-unit-ru) to make RU values more stable [#8391](https://github.com/pingcap/tiflash/issues/8391) @[guo-shaoge](https://github.com/guo-shaoge) + - Reduce the impact of disk performance jitter on read latency [#8583](https://github.com/pingcap/tiflash/issues/8583) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Reduce the impact of background GC tasks on read and write task latency [#8650](https://github.com/pingcap/tiflash/issues/8650) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + Backup & Restore (BR) + + - Improve the speed of merging SST files during data restore by using a more efficient algorithm [#50613](https://github.com/pingcap/tidb/issues/50613) @[Leavrth](https://github.com/Leavrth) + - Support creating databases in batch during data restore [#50767](https://github.com/pingcap/tidb/issues/50767) @[Leavrth](https://github.com/Leavrth) + - Support ingesting SST files in batch during data restore [#16267](https://github.com/tikv/tikv/issues/16267) @[3pointer](https://github.com/3pointer) + - Print the information of the slowest Region that affects global checkpoint advancement in logs and metrics during log backups [#51046](https://github.com/pingcap/tidb/issues/51046) @[YuJuncen](https://github.com/YuJuncen) + - Improve the table creation performance of the `RESTORE` statement in scenarios with large datasets [#48301](https://github.com/pingcap/tidb/issues/48301) @[Leavrth](https://github.com/Leavrth) + - BR can pause Region merging by setting the `merge-schedule-limit` configuration to `0` [#7148](https://github.com/tikv/pd/issues/7148) @[BornChanger](https://github.com/3pointer) + - Refactor the BR exception handling mechanism to increase tolerance for unknown errors [#47656](https://github.com/pingcap/tidb/issues/47656) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Support searching TiCDC logs in the TiDB Dashboard [#10263](https://github.com/pingcap/tiflow/issues/10263) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support [querying the downstream synchronization status of a changefeed](https://docs.pingcap.com/tidb/v7.5/ticdc-open-api-v2#query-whether-a-specific-replication-task-is-completed), which helps you determine whether the upstream data changes received by TiCDC have been synchronized to the downstream system completely [#10289](https://github.com/pingcap/tiflow/issues/10289) @[hongyunyan](https://github.com/hongyunyan) + - Improve the performance of TiCDC replicating data to object storage by increasing parallelism [#10098](https://github.com/pingcap/tiflow/issues/10098) @[CharlesCheung96](https://github.com/CharlesCheung96) + + + TiDB Lightning + + - Improve the performance of `ALTER TABLE` when importing a large number of small tables [#50105](https://github.com/pingcap/tidb/issues/50105) @[D3Hunter](https://github.com/D3Hunter) + +## Bug fixes + ++ TiDB + + - Fix the issue that setting the system variable `tidb_service_scope` does not take effect [#49245](https://github.com/pingcap/tidb/issues/49245) @[ywqzzy](https://github.com/ywqzzy) + - Fix the issue that the communication protocol cannot handle packets larger than or equal to 16 MB when compression is enabled [#47157](https://github.com/pingcap/tidb/issues/47157) [#47161](https://github.com/pingcap/tidb/issues/47161) @[dveeden](https://github.com/dveeden) + - Fix the issue that the `approx_percentile` function might cause TiDB panic [#40463](https://github.com/pingcap/tidb/issues/40463) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that TiDB might implicitly insert the `from_binary` function when the argument of a string function is a `NULL` constant, causing some expressions unable to be pushed down to TiFlash [#49526](https://github.com/pingcap/tidb/issues/49526) @[YangKeao](https://github.com/YangKeao) + - Fix the goroutine leak issue that might occur when the `HashJoin` operator fails to spill to disk [#50841](https://github.com/pingcap/tidb/issues/50841) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that `BIT` type columns might cause query errors due to decode failures when they are involved in calculations of some functions [#49566](https://github.com/pingcap/tidb/issues/49566) [#50850](https://github.com/pingcap/tidb/issues/50850) [#50855](https://github.com/pingcap/tidb/issues/50855) @[jiyfhust](https://github.com/jiyfhust) + - Fix the goroutine leak issue that occurs when the memory usage of CTE queries exceed limits [#50337](https://github.com/pingcap/tidb/issues/50337) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that wrong results might be returned when TiFlash late materialization processes associated columns [#49241](https://github.com/pingcap/tidb/issues/49241) [#51204](https://github.com/pingcap/tidb/issues/51204) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that the background job thread of TiDB might panic when TiDB records historical statistics [#49076](https://github.com/pingcap/tidb/issues/49076) @[hawkingrei](https://github.com/hawkingrei) + - Fix the error that might occur when TiDB merges histograms of global statistics for partitioned tables [#49023](https://github.com/pingcap/tidb/issues/49023) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the historical statistics of the `stats_meta` table are not updated after a partition is dropped [#49334](https://github.com/pingcap/tidb/issues/49334) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue of incorrect query results caused by multi-valued indexes mistakenly selected as the `Index Join` probe side [#50382](https://github.com/pingcap/tidb/issues/50382) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the `USE_INDEX_MERGE` hint does not take effect on multi-valued indexes [#50553](https://github.com/pingcap/tidb/issues/50553) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that users might get errors when querying the `INFORMATION_SCHEMA.ANALYZE_STATUS` system table [#48835](https://github.com/pingcap/tidb/issues/48835) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue of wrong query results due to TiDB incorrectly eliminating constant values in `group by` [#38756](https://github.com/pingcap/tidb/issues/38756) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `processed_rows` of the `ANALYZE` task on a table might exceed the total number of rows in that table [#50632](https://github.com/pingcap/tidb/issues/50632) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that TiDB might panic when using the `EXECUTE` statement to execute `PREPARE STMT` after the `tidb_enable_prepared_plan_cache` system variable is enabled and then disabled [#49344](https://github.com/pingcap/tidb/issues/49344) @[qw4990](https://github.com/qw4990) + - Fix the `Column ... in from clause is ambiguous` error that might occur when a query uses `NATURAL JOIN` [#32044](https://github.com/pingcap/tidb/issues/32044) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that using a multi-valued index to access an empty JSON array might return incorrect results [#50125](https://github.com/pingcap/tidb/issues/50125) @[YangKeao](https://github.com/YangKeao) + - Fix the `Can't find column ...` error that might occur when aggregate functions are used for group calculations [#50926](https://github.com/pingcap/tidb/issues/50926) @[qw4990](https://github.com/qw4990) + - Fix the issue that the control of `SET_VAR` for variables of the string type might become invalid [#50507](https://github.com/pingcap/tidb/issues/50507) @[qw4990](https://github.com/qw4990) + - Fix the issue that high CPU usage of TiDB occurs due to long-term memory pressure caused by `tidb_server_memory_limit` [#48741](https://github.com/pingcap/tidb/issues/48741) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that the completion times of two DDL tasks with dependencies are incorrectly sequenced [#49498](https://github.com/pingcap/tidb/issues/49498) @[tangenta](https://github.com/tangenta) + - Fix the issue that illegal optimizer hints might cause valid hints to be ineffective [#49308](https://github.com/pingcap/tidb/issues/49308) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that DDL statements with the `CHECK` constraint are stuck [#47632](https://github.com/pingcap/tidb/issues/47632) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the behavior of the `ENFORCED` option in the `CHECK` constraint is inconsistent with MySQL 8.0 [#47567](https://github.com/pingcap/tidb/issues/47567) [#47631](https://github.com/pingcap/tidb/issues/47631) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that CTE queries might report an error `type assertion for CTEStorageMap failed` during the retry process [#46522](https://github.com/pingcap/tidb/issues/46522) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `DELETE` and `UPDATE` statements using index lookup might report an error when `tidb_multi_statement_mode` mode is enabled [#50012](https://github.com/pingcap/tidb/issues/50012) @[tangenta](https://github.com/tangenta) + - Fix the issue that `UPDATE` or `DELETE` statements containing `WITH RECURSIVE` CTEs might produce incorrect results [#48969](https://github.com/pingcap/tidb/issues/48969) @[winoros](https://github.com/winoros) + - Fix the issue that the optimizer incorrectly converts TiFlash selection path to the DUAL table in specific scenarios [#49285](https://github.com/pingcap/tidb/issues/49285) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that the same query plan has different `PLAN_DIGEST` values in some cases [#47634](https://github.com/pingcap/tidb/issues/47634) @[King-Dylan](https://github.com/King-Dylan) + - Fix the issue that after the time window for automatic statistics updates is configured, statistics might still be updated outside that time window [#49552](https://github.com/pingcap/tidb/issues/49552) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the query result is incorrect when an `ENUM` type column is used as the join key [#48991](https://github.com/pingcap/tidb/issues/48991) @[winoros](https://github.com/winoros) + - Fix the issue that executing `UNIQUE` index lookup with an `ORDER BY` clause might cause an error [#49920](https://github.com/pingcap/tidb/issues/49920) @[jackysp](https://github.com/jackysp) + - Fix the issue that `LIMIT` in multi-level nested `UNION` queries might become ineffective [#49874](https://github.com/pingcap/tidb/issues/49874) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the result of `COUNT(INT)` calculated by MPP might be incorrect [#48643](https://github.com/pingcap/tidb/issues/48643) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that parsing invalid values of `ENUM` or `SET` types would directly cause SQL statement errors [#49487](https://github.com/pingcap/tidb/issues/49487) @[winoros](https://github.com/winoros) + - Fix the issue that TiDB panics and reports an error `invalid memory address or nil pointer dereference` [#42739](https://github.com/pingcap/tidb/issues/42739) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the issue that executing `UNION ALL` with the DUAL table as the first subnode might cause an error [#48755](https://github.com/pingcap/tidb/issues/48755) @[winoros](https://github.com/winoros) + - Fix the issue that common hints do not take effect in `UNION ALL` statements [#50068](https://github.com/pingcap/tidb/issues/50068) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that TiDB server might panic during graceful shutdown [#36793](https://github.com/pingcap/tidb/issues/36793) @[bb7133](https://github.com/bb7133) + - Fix the issue that Daylight Saving Time is displayed incorrectly in some time zones [#49586](https://github.com/pingcap/tidb/issues/49586) @[overvenus](https://github.com/overvenus) + - Fix the issue that static `CALIBRATE RESOURCE` relies on the Prometheus data [#49174](https://github.com/pingcap/tidb/issues/49174) @[glorv](https://github.com/glorv) + - Fix the issue that hints cannot be used in `REPLACE INTO` statements [#34325](https://github.com/pingcap/tidb/issues/34325) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that executing queries containing the `GROUP_CONCAT(ORDER BY)` syntax might return errors [#49986](https://github.com/pingcap/tidb/issues/49986) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that TiDB server might consume a significant amount of resources when the enterprise plugin for audit logging is used [#49273](https://github.com/pingcap/tidb/issues/49273) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that using old interfaces might cause inconsistent metadata for tables [#49751](https://github.com/pingcap/tidb/issues/49751) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that disabling `tidb_enable_collect_execution_info` causes the coprocessor cache to panic [#48212](https://github.com/pingcap/tidb/issues/48212) @[you06](https://github.com/you06) + - Fix the issue that executing `ALTER TABLE ... LAST PARTITION` fails when the partition column type is `DATETIME` [#48814](https://github.com/pingcap/tidb/issues/48814) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the `COMMIT` or `ROLLBACK` operation executed through `COM_STMT_EXECUTE` fails to terminate transactions that have timed out [#49151](https://github.com/pingcap/tidb/issues/49151) @[zyguan](https://github.com/zyguan) + - Fix the issue that histogram statistics might not be parsed into readable strings when the histogram boundary contains `NULL` [#49823](https://github.com/pingcap/tidb/issues/49823) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that queries containing common table expressions (CTEs) unexpectedly get stuck when the memory limit is exceeded [#49096](https://github.com/pingcap/tidb/issues/49096) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that data is inconsistent under the TiDB Distributed eXecution Framework (DXF) when executing `ADD INDEX` after the DDL Owner is network isolated [#49773](https://github.com/pingcap/tidb/issues/49773) @[tangenta](https://github.com/tangenta) + - Fix the issue that the auto-increment ID allocation reports an error due to concurrent conflicts when using an auto-increment column with `AUTO_ID_CACHE=1` [#50519](https://github.com/pingcap/tidb/issues/50519) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB might panic when a query contains the Apply operator and the `fatal error: concurrent map writes` error occurs [#50347](https://github.com/pingcap/tidb/issues/50347) @[SeaRise](https://github.com/SeaRise) + - Fix the TiDB node panic issue that occurs when DDL `jobID` is restored to 0 [#46296](https://github.com/pingcap/tidb/issues/46296) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that query results are incorrect due to `STREAM_AGG()` incorrectly handling CI [#49902](https://github.com/pingcap/tidb/issues/49902) @[wshwsh12](https://github.com/wshwsh12) + - Mitigate the issue that TiDB nodes might encounter OOM errors when dealing with a large number of tables or partitions [#50077](https://github.com/pingcap/tidb/issues/50077) @[zimulala](https://github.com/zimulala) + - Fix the issue that the `LEADING` hint does not take effect in `UNION ALL` statements [#50067](https://github.com/pingcap/tidb/issues/50067) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `LIMIT` and `OPRDERBY` might be invalid in nested `UNION` queries [#49377](https://github.com/pingcap/tidb/issues/49377) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that a query containing the IndexHashJoin operator gets stuck when memory exceeds `tidb_mem_quota_query` [#49033](https://github.com/pingcap/tidb/issues/49033) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that TiDB returns wrong query results when processing `ENUM` or `SET` types by constant propagation [#49440](https://github.com/pingcap/tidb/issues/49440) @[winoros](https://github.com/winoros) + - Fix the issue that executing `SELECT INTO OUTFILE` using the `PREPARE` method incorrectly returns a success message instead of an error [#49166](https://github.com/pingcap/tidb/issues/49166) @[qw4990](https://github.com/qw4990) + - Fix the issue that enforced sorting might become ineffective when a query uses optimizer hints (such as `STREAM_AGG()`) that enforce sorting and its execution plan contains `IndexMerge` [#49605](https://github.com/pingcap/tidb/issues/49605) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that tables with `AUTO_ID_CACHE=1` might lead to gRPC client leaks when there are a large number of tables [#48869](https://github.com/pingcap/tidb/issues/48869) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that in non-strict mode (`sql_mode = ''`), truncation during executing `INSERT` still reports an error [#49369](https://github.com/pingcap/tidb/issues/49369) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that using the `_` wildcard in `LIKE` when the data contains trailing spaces can result in incorrect query results [#48983](https://github.com/pingcap/tidb/issues/48983) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that executing `ADMIN CHECK` after updating the `tidb_mem_quota_query` system variable returns `ERROR 8175` [#49258](https://github.com/pingcap/tidb/issues/49258) @[tangenta](https://github.com/tangenta) + - Fix the issue of excessive statistical error in constructing statistics caused by Golang's implicit conversion algorithm [#49801](https://github.com/pingcap/tidb/issues/49801) @[qw4990](https://github.com/qw4990) + - Fix the issue that queries containing CTEs report `runtime error: index out of range [32] with length 32` when `tidb_max_chunk_size` is set to a small value [#48808](https://github.com/pingcap/tidb/issues/48808) @[guo-shaoge](https://github.com/guo-shaoge) + ++ TiKV + + - Fix the issue that enabling `tidb_enable_row_level_checksum` might cause TiKV to panic [#16371](https://github.com/tikv/tikv/issues/16371) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that TiKV might panic when gRPC threads are checking `is_shutdown` [#16236](https://github.com/tikv/tikv/issues/16236) @[pingyu](https://github.com/pingyu) + - Fix the issue that TiKV converts the time zone incorrectly for Brazil and Egypt [#16220](https://github.com/tikv/tikv/issues/16220) @[overvenus](https://github.com/overvenus) + - Fix the issue that `blob-run-mode` in Titan cannot be updated online [#15978](https://github.com/tikv/tikv/issues/15978) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that TiDB and TiKV might produce inconsistent results when processing `DECIMAL` arithmetic multiplication truncation [#16268](https://github.com/tikv/tikv/issues/16268) @[solotzg](https://github.com/solotzg) + - Fix the issue that Flashback might get stuck when encountering `notLeader` or `regionNotFound` [#15712](https://github.com/tikv/tikv/issues/15712) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that damaged SST files might be spread to other TiKV nodes [#15986](https://github.com/tikv/tikv/issues/15986) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that if TiKV runs extremely slowly, it might panic after Region merge [#16111](https://github.com/tikv/tikv/issues/16111) @[overvenus](https://github.com/overvenus) + - Fix the issue that the joint state of DR Auto-Sync might time out when scaling out [#15817](https://github.com/tikv/tikv/issues/15817) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that Resolved TS might be blocked for two hours [#11847](https://github.com/tikv/tikv/issues/11847) [#15520](https://github.com/tikv/tikv/issues/15520) [#39130](https://github.com/pingcap/tidb/issues/39130) @[overvenus](https://github.com/overvenus) + - Fix the issue that `cast_duration_as_time` might return incorrect results [#16211](https://github.com/tikv/tikv/issues/16211) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that TiKV hangs in corner cases (for example, when disk I/O operations are blocked), which affects availability [#16368](https://github.com/tikv/tikv/issues/16368) @[LykxSassinator](https://github.com/LykxSassinator) + ++ PD + + - Fix the issue that querying resource groups in batch might cause PD to panic [#7206](https://github.com/tikv/pd/issues/7206) @[nolouch](https://github.com/nolouch) + - Fix the issue that PD cannot read resource limitations when it is started with `systemd` [#7628](https://github.com/tikv/pd/issues/7628) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that continuous jitter in PD disk latency might cause PD to fail to select a new leader [#7251](https://github.com/tikv/pd/issues/7251) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that a network partition in PD might cause scheduling not to be started immediately [#7016](https://github.com/tikv/pd/issues/7016) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the PD monitoring item `learner-peer-count` does not synchronize the old value after a leader switch [#7728](https://github.com/tikv/pd/issues/7728) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that when PD leader is transferred and there is a network partition between the new leader and the PD client, the PD client fails to update the information of the leader [#7416](https://github.com/tikv/pd/issues/7416) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix some security issues by upgrading the version of Gin Web Framework from v1.8.1 to v1.9.1 [#7438](https://github.com/tikv/pd/issues/7438) @[niubell](https://github.com/niubell) + - Fix the issue that the orphan peer is deleted when the number of replicas does not meet the requirements [#7584](https://github.com/tikv/pd/issues/7584) @[bufferflies](https://github.com/bufferflies) + - Fix the issue that querying a Region without a leader using `pd-ctl` might cause PD to panic [#7630](https://github.com/tikv/pd/issues/7630) @[rleungx](https://github.com/rleungx) + ++ TiFlash + + - Fix the issue that TiFlash might panic due to unstable network connections with PD during replica migration [#8323](https://github.com/pingcap/tiflash/issues/8323) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that removing and then re-adding TiFlash replicas might lead to data corruption in TiFlash [#8695](https://github.com/pingcap/tiflash/issues/8695) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix a potential issue that `FLASHBACK TABLE` or `RECOVER TABLE` might fail to recover data of some TiFlash replicas if `DROP TABLE` is executed immediately after data insertion [#8395](https://github.com/pingcap/tiflash/issues/8395) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix incorrect display of maximum percentile time for some panels in Grafana [#8076](https://github.com/pingcap/tiflash/issues/8076) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might crash during remote reads [#8685](https://github.com/pingcap/tiflash/issues/8685) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiFlash incorrectly handles `ENUM` when the `ENUM` value is 0 [#8311](https://github.com/pingcap/tiflash/issues/8311) @[solotzg](https://github.com/solotzg) + - Fix the issue that short queries executed successfully print excessive info logs [#8592](https://github.com/pingcap/tiflash/issues/8592) @[windtalker](https://github.com/windtalker) + - Fix the issue that the memory usage increases significantly due to slow queries [#8564](https://github.com/pingcap/tiflash/issues/8564) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that the `lowerUTF8` and `upperUTF8` functions do not allow characters in different cases to occupy different bytes [#8484](https://github.com/pingcap/tiflash/issues/8484) @[gengliqi](https://github.com/gengliqi) + - Fix the potential OOM issue that might occur when scanning multiple partitioned tables during stream read [#8505](https://github.com/pingcap/tiflash/issues/8505) @[gengliqi](https://github.com/gengliqi) + - Fix the issue of memory leak when TiFlash encounters memory limitation during query [#8447](https://github.com/pingcap/tiflash/issues/8447) @[JinheLin](https://github.com/JinheLin) + - Fix the TiFlash panic issue when TiFlash encounters conflicts during concurrent DDL execution [#8578](https://github.com/pingcap/tiflash/issues/8578) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash panics after executing `ALTER TABLE ... MODIFY COLUMN ... NOT NULL`, which changes nullable columns to non-nullable [#8419](https://github.com/pingcap/tiflash/issues/8419) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that query results are incorrect when querying with filtering conditions like `ColumnRef in (Literal, Func...)` [#8631](https://github.com/pingcap/tiflash/issues/8631) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that data of TiFlash replicas would still be garbage collected after executing `FLASHBACK DATABASE` [#8450](https://github.com/pingcap/tiflash/issues/8450) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might not be able to select the GC owner of object storage data under the disaggregated storage and compute architecture [#8519](https://github.com/pingcap/tiflash/issues/8519) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the random invalid memory access issue that might occur with `GREATEST` or `LEAST` functions containing constant string parameters [#8604](https://github.com/pingcap/tiflash/issues/8604) @[windtalker](https://github.com/windtalker) + - Fix the issue that TiFlash replica data might be accidentally deleted after performing point-in-time recovery (PITR) or executing `FLASHBACK CLUSTER TO`, which might result in data anomalies [#8777](https://github.com/pingcap/tiflash/issues/8777) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash Anti Semi Join might return incorrect results when the join includes non-equivalent conditions [#8791](https://github.com/pingcap/tiflash/issues/8791) @[windtalker](https://github.com/windtalker) ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that data restore is slowed down due to absence of a leader on a TiKV node [#50566](https://github.com/pingcap/tidb/issues/50566) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that full restore still requires the target cluster to be empty after the `--filter` option is specified [#51009](https://github.com/pingcap/tidb/issues/51009) @[3pointer](https://github.com/3pointer) + - Fix the issue that when resuming from a checkpoint after data restore fails, an error `the target cluster is not fresh` occurs [#50232](https://github.com/pingcap/tidb/issues/50232) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that stopping a log backup task causes TiDB to crash [#50839](https://github.com/pingcap/tidb/issues/50839) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the `Unsupported collation` error is reported when you restore data from backups of an old version [#49466](https://github.com/pingcap/tidb/issues/49466) @[3pointer](https://github.com/3pointer) + - Fix the issue that the log backup task can start but does not work properly if failing to connect to PD during task initialization [#16056](https://github.com/tikv/tikv/issues/16056) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that BR generates incorrect URIs for external storage files [#48452](https://github.com/pingcap/tidb/issues/48452) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that log backup gets stuck after changing the TiKV IP address on the same node [#50445](https://github.com/pingcap/tidb/issues/50445) @[3pointer](https://github.com/3pointer) + - Fix the issue that BR cannot retry when encountering an error while reading file content from S3 [#49942](https://github.com/pingcap/tidb/issues/49942) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Fix the issue that the sink module fails to restart correctly after encountering an error when Syncpoint is enabled (`enable-sync-point = true`) [#10091](https://github.com/pingcap/tiflow/issues/10091) @[hicqu](https://github.com/hicqu) + - Fix the issue that the file sequence number generated by the storage service might not increment correctly when using the storage sink [#10352](https://github.com/pingcap/tiflow/issues/10352) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the Syncpoint table might be incorrectly replicated [#10576](https://github.com/pingcap/tiflow/issues/10576) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that OAuth2.0, TLS, and mTLS cannot be enabled properly when using Apache Pulsar as the downstream [#10602](https://github.com/pingcap/tiflow/issues/10602) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that TiCDC returns the `ErrChangeFeedAlreadyExists` error when concurrently creating multiple changefeeds [#10430](https://github.com/pingcap/tiflow/issues/10430) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the changefeed `resolved ts` does not advance in extreme cases [#10157](https://github.com/pingcap/tiflow/issues/10157) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC mistakenly closes the connection with TiKV in certain special scenarios [#10239](https://github.com/pingcap/tiflow/issues/10239) @[hicqu](https://github.com/hicqu) + - Fix the issue that the TiCDC server might panic when replicating data to an object storage service [#10137](https://github.com/pingcap/tiflow/issues/10137) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that the changefeed reports an error after `TRUNCATE PARTITION` is executed on the upstream table [#10522](https://github.com/pingcap/tiflow/issues/10522) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that after filtering out `add table partition` events is configured in `ignore-event`, TiCDC does not replicate other types of DML changes for related partitions to the downstream [#10524](https://github.com/pingcap/tiflow/issues/10524) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the potential data race issue during `kv-client` initialization [#10095](https://github.com/pingcap/tiflow/issues/10095) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Fix the issue that a migration task error occurs when the downstream table structure contains `shard_row_id_bits` [#10308](https://github.com/pingcap/tiflow/issues/10308) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that DM encounters "event type truncate not valid" error that causes the upgrade to fail [#10282](https://github.com/pingcap/tiflow/issues/10282) @[GMHDBJD](https://github.com/GMHDBJD) diff --git a/releases/release-7.5.2.md b/releases/release-7.5.2.md new file mode 100644 index 0000000000000..d9bb4885dfe03 --- /dev/null +++ b/releases/release-7.5.2.md @@ -0,0 +1,253 @@ +--- +title: TiDB 7.5.2 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.5.2. +--- + +# TiDB 7.5.2 Release Notes + +Release date: June 13, 2024 + +TiDB version: 7.5.2 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.5/production-deployment-using-tiup) + +## Compatibility changes + +- Add a TiKV configuration item [`track-and-verify-wals-in-manifest`](https://docs.pingcap.com/tidb/v7.5/tikv-configuration-file#track-and-verify-wals-in-manifest-new-in-v659-v715-and-v752) for RocksDB, which helps you investigate possible corruption of Write Ahead Log (WAL) [#16549](https://github.com/tikv/tikv/issues/16549) @[v01dstar](https://github.com/v01dstar) +- Must set the line terminator when using TiDB Lightning `strict-format` or `SPLIT_FILE` to import CSV files [#37338](https://github.com/pingcap/tidb/issues/37338) @[lance6716](https://github.com/lance6716) +- Add the `sink.open.output-old-value` configuration item for TiCDC Open Protocol to control whether to output the value before the update to the downstream [#10916](https://github.com/pingcap/tiflow/issues/10916) @[sdojjy](https://github.com/sdojjy) +- In earlier versions, when processing a transaction containing `UPDATE` changes, if the primary key or non-null unique index value is modified in an `UPDATE` event, TiCDC splits this event into `DELETE` and `INSERT` events. Starting from v7.5.2, when using the MySQL sink, TiCDC splits an `UPDATE` event into `DELETE` and `INSERT` events if the transaction `commitTS` for the `UPDATE` change is less than TiCDC `thresholdTS` (which is the current timestamp fetched from PD when TiCDC starts replicating the corresponding table to the downstream). This behavior change addresses the issue of downstream data inconsistencies caused by the potentially incorrect order of `UPDATE` events received by TiCDC, which can lead to an incorrect order of split `DELETE` and `INSERT` events. For more information, see [documentation](https://docs.pingcap.com/tidb/v7.5/ticdc-split-update-behavior#split-update-events-for-mysql-sinks). [#10918](https://github.com/pingcap/tiflow/issues/10918) @[lidezhu](https://github.com/lidezhu) + +## Improvements + ++ TiDB + + - Optimize the issue that the `ANALYZE` statement blocks the metadata lock [#47475](https://github.com/pingcap/tidb/issues/47475) @[wjhuang2016](https://github.com/wjhuang2016) + - Improve the MySQL compatibility of expression default values displayed in the output of `SHOW CREATE TABLE` [#52939](https://github.com/pingcap/tidb/issues/52939) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Enhance the handling of DNF items that are always `false` by directly ignoring such filter conditions, thus avoiding unnecessary full table scans [#40997](https://github.com/pingcap/tidb/issues/40997) @[hi-rustin](https://github.com/Rustin170506) + - Optimize the statistics for the execution process of the TiFlash `TableScan` operator in `EXPLAIN ANALYZE` [#51727](https://github.com/pingcap/tidb/issues/51727) @[JinheLin](https://github.com/JinheLin) + - Remove stores without Regions during MPP load balancing [#52313](https://github.com/pingcap/tidb/issues/52313) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Support loading Regions in batch from PD to speed up the conversion process from the KV range to Regions when querying large tables [#51326](https://github.com/pingcap/tidb/issues/51326) @[SeaRise](https://github.com/SeaRise) + - On the `Resource Control` monitoring page, add a new panel `RU(Max)` to show the maximum RU consumption rate for each resource group [#49318](https://github.com/pingcap/tidb/issues/49318) @[nolouch](https://github.com/nolouch) + - Improve sync load performance to reduce latency in loading statistics [#52994](https://github.com/pingcap/tidb/issues/52294) [hawkingrei](https://github.com/hawkingrei) + - Increase concurrency of statistics initialization to speed up startup [#52466](https://github.com/pingcap/tidb/issues/52466) [#52102](https://github.com/pingcap/tidb/issues/52102) [#52553](https://github.com/pingcap/tidb/issues/52553) [hawkingrei](https://github.com/hawkingrei) + ++ TiKV + + - Adjust the log level of coprocessor errors from `warn` to `debug` to reduce unnecessary logs of the cluster [#15881](https://github.com/tikv/tikv/issues/15881) @[cfzjywxk](https://github.com/cfzjywxk) + - Add monitoring metrics for the queue time for processing CDC events to facilitate troubleshooting downstream CDC event latency issues [#16282](https://github.com/tikv/tikv/issues/16282) @[hicqu](https://github.com/hicqu) + - Avoid performing IO operations on snapshot files in raftstore threads to improve TiKV stability [#16564](https://github.com/tikv/tikv/issues/16564) @[Connor1996](https://github.com/Connor1996) + - Add slow logs for peer and store messages [#16600](https://github.com/tikv/tikv/issues/16600) @[Connor1996](https://github.com/Connor1996) + - When TiKV detects the existence of corrupted SST files, it logs the specific reasons for the corruption [#16308](https://github.com/tikv/tikv/issues/16308) @[overvenus](https://github.com/overvenus) + - Remove unnecessary async blocks to reduce memory usage [#16540](https://github.com/tikv/tikv/issues/16540) @[overvenus](https://github.com/overvenus) + - Accelerate the shutdown speed of TiKV [#16680](https://github.com/tikv/tikv/issues/16680) @[LykxSassinator](https://github.com/LykxSassinator) + ++ PD + + - Upgrade the etcd version to v3.4.30 [#7904](https://github.com/tikv/pd/issues/7904) @[JmPotato](https://github.com/JmPotato) + - Add the monitoring metric for the maximum Request Unit (RU) per second [#7908](https://github.com/tikv/pd/issues/7908) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Mitigate the issue that TiFlash might panic due to updating certificates after TLS is enabled [#8535](https://github.com/pingcap/tiflash/issues/8535) @[windtalker](https://github.com/windtalker) + ++ Tools + + + Backup & Restore (BR) + + - BR cleans up empty SST files during data recovery [#16005](https://github.com/tikv/tikv/issues/16005) @[Leavrth](https://github.com/Leavrth) + - Add PITR integration test cases to cover compatibility testing for log backup and adding index acceleration [#51987](https://github.com/pingcap/tidb/issues/51987) @[Leavrth](https://github.com/Leavrth) + - Enhance the tolerance of log backup to merge operations. When encountering a reasonably long merge operation, log backup tasks are less likely to enter the error state [#16554](https://github.com/tikv/tikv/issues/16554) @[YuJuncen](https://github.com/YuJuncen) + - Improve the table creation performance of the `RESTORE` statement in scenarios with large datasets [#48301](https://github.com/pingcap/tidb/issues/48301) @[Leavrth](https://github.com/Leavrth) + - Support pre-allocating Table ID during the restore process to maximize the reuse of Table ID and improve restore performance [#51736](https://github.com/pingcap/tidb/issues/51736) @[Leavrth](https://github.com/Leavrth) + - Remove the invalid verification for active DDL jobs when log backup starts [#52733](https://github.com/pingcap/tidb/issues/52733) @[Leavrth](https://github.com/Leavrth) + - Remove an outdated compatibility check when using Google Cloud Storage (GCS) as the external storage [#50533](https://github.com/pingcap/tidb/issues/50533) @[lance6716](https://github.com/lance6716) + - Increase the number of retries for failures caused by DNS errors [#53029](https://github.com/pingcap/tidb/issues/53029) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Improve memory stability during data recovery using redo logs to reduce the probability of OOM [#10900](https://github.com/pingcap/tiflow/issues/10900) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Significantly improve the stability of data replication in transaction conflict scenarios, with up to 10 times performance improvement [#10896](https://github.com/pingcap/tiflow/issues/10896) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Enable the PD client forwarding function to make TiCDC more stable during network isolation between TiCDC and the PD leader [#10849](https://github.com/pingcap/tiflow/issues/10849) @[asddongmen](https://github.com/asddongmen) + - Improve the initialization speed of replication tasks [#11124](https://github.com/pingcap/tiflow/issues/11124) @[asddongmen](https://github.com/asddongmen) + - Initialize replication tasks asynchronously to reduce initialization time for the processor and owner [#10845](https://github.com/pingcap/tiflow/issues/10845) @[sdojjy](https://github.com/sdojjy) + - Detect the Kafka cluster version automatically to improve compatibility with Kafka [#10852](https://github.com/pingcap/tiflow/issues/10852) @[wk989898](https://github.com/wk989898) + +## Bug fixes + ++ TiDB + + - Fix the issue of inconsistent data indexes caused by concurrent DML operations when adding a unique index [#52914](https://github.com/pingcap/tidb/issues/52914) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue of inconsistent data indexes caused by adding indexes with multi-schema changes on partitioned tables [#52080](https://github.com/pingcap/tidb/issues/52080) @[tangenta](https://github.com/tangenta) + - Fix the issue of inconsistent data indexes caused by adding multi-valued indexes [#51162](https://github.com/pingcap/tidb/issues/51162) @[ywqzzy](https://github.com/ywqzzy) + - Fix the issue that DDL operations get stuck due to network problems [#47060](https://github.com/pingcap/tidb/issues/47060) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that TiDB might report an error due to GC when loading statistics at startup [#53592](https://github.com/pingcap/tidb/issues/53592) @[you06](https://github.com/you06) + - Fix the issue that TiDB might send requests to unready TiKV nodes [#50758](https://github.com/pingcap/tidb/issues/50758) @[zyguan](https://github.com/zyguan) + - Fix the issue that Stale Read might miss after a TiKV rolling restart [#52193](https://github.com/pingcap/tidb/issues/52193) @[zyguan](https://github.com/zyguan) + - Fix the issue that data race might occur during KV request retries, leading to TiDB panics [#51921](https://github.com/pingcap/tidb/issues/51921) @[zyguan](https://github.com/zyguan) + - Fix the issue that TiDB might panic when parsing index data [#47115](https://github.com/pingcap/tidb/issues/47115) @[zyguan](https://github.com/zyguan) + - Fix the issue that TiDB might panic when the JOIN condition contains an implicit type conversion [#46556](https://github.com/pingcap/tidb/issues/46556) @[qw4990](https://github.com/qw4990) + - Fix the issue that comparing a column of `YEAR` type with an unsigned integer that is out of range causes incorrect results [#50235](https://github.com/pingcap/tidb/issues/50235) @[qw4990](https://github.com/qw4990) + - Fix the issue that subqueries in an `UPDATE` list might cause TiDB to panic [#52687](https://github.com/pingcap/tidb/issues/52687) @[winoros](https://github.com/winoros) + - Fix the overflow issue of the `Longlong` type in predicates [#45783](https://github.com/pingcap/tidb/issues/45783) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `SELECT INTO OUTFILE` does not work when clustered indexes are used as predicates [#42093](https://github.com/pingcap/tidb/issues/42093) @[qw4990](https://github.com/qw4990) + - Fix the issue that the TopN operator might be pushed down incorrectly [#37986](https://github.com/pingcap/tidb/issues/37986) @[qw4990](https://github.com/qw4990) + - Fix the issue that an empty projection causes TiDB to panic [#49109](https://github.com/pingcap/tidb/issues/49109) @[winoros](https://github.com/winoros) + - Fix the issue that Index Merge incorrectly pushes partial limit down when index plans are kept ordered [#52947](https://github.com/pingcap/tidb/issues/52947) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that using a view does not work in recursive CTE [#49721](https://github.com/pingcap/tidb/issues/49721) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that unstable unique IDs of columns might cause the `UPDATE` statement to return errors [#53236](https://github.com/pingcap/tidb/issues/53236) @[winoros](https://github.com/winoros) + - Fix the issue that TiDB panics when executing the `SHOW ERRORS` statement with a predicate that is always `true` [#46962](https://github.com/pingcap/tidb/issues/46962) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that the `final` AggMode and the `non-final` AggMode cannot coexist in Massively Parallel Processing (MPP) [#51362](https://github.com/pingcap/tidb/issues/51362) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that a wrong TableDual plan causes empty query results [#50051](https://github.com/pingcap/tidb/issues/50051) @[onlyacat](https://github.com/onlyacat) + - Fix the issue that TiDB might panic when initializing statistics after enabling both `lite-init-stats` and `concurrently-init-stats` [#52223](https://github.com/pingcap/tidb/issues/52223) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `NO_JOIN` hints do not work with `CREATE BINDING` [#52813](https://github.com/pingcap/tidb/issues/52813) @[qw4990](https://github.com/qw4990) + - Fix the issue that subqueries included in the `ALL` function might cause incorrect results [#52755](https://github.com/pingcap/tidb/issues/52755) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `VAR_SAMP()` cannot be used as a window function [#52933](https://github.com/pingcap/tidb/issues/52933) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that column pruning without using shallow copies of slices might cause TiDB to panic [#52768](https://github.com/pingcap/tidb/issues/52768) @[winoros](https://github.com/winoros) + - Fix the issue that adding a unique index might cause TiDB to panic [#52312](https://github.com/pingcap/tidb/issues/52312) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the TiDB server is marked as health before the initialization is complete [#51596](https://github.com/pingcap/tidb/issues/51596) @[shenqidebaozi](https://github.com/shenqidebaozi) + - Fix the issue that the type returned by the `IFNULL` function is inconsistent with MySQL [#51765](https://github.com/pingcap/tidb/issues/51765) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that parallel `Apply` might generate incorrect results when the table has a clustered index [#51372](https://github.com/pingcap/tidb/issues/51372) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that query results might be incorrect when the `HAVING` clause in a subquery contains correlated columns [#51107](https://github.com/pingcap/tidb/issues/51107) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that querying the `TIDB_HOT_REGIONS` table might incorrectly return `INFORMATION_SCHEMA` tables [#50810](https://github.com/pingcap/tidb/issues/50810) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that automatic statistics collection is triggered before the initialization of statistics finishes [#52346](https://github.com/pingcap/tidb/issues/52346) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that AutoID Leader change might cause the value of the auto-increment column to decrease in the case of `AUTO_ID_CACHE=1` [#52600](https://github.com/pingcap/tidb/issues/52600) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that query results might be incorrect when you use Common Table Expressions (CTE) to access partitioned tables with missing statistics [#51873](https://github.com/pingcap/tidb/issues/51873) @[qw4990](https://github.com/qw4990) + - Fix the incorrect calculation and display of the number of connections (Connection Count) on the TiDB Dashboard Monitoring page [#51889](https://github.com/pingcap/tidb/issues/51889) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that DDL operations get stuck when restoring a table with the foreign key [#51838](https://github.com/pingcap/tidb/issues/51838) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that getting the default value of a column returns an error if the column default value is dropped [#50043](https://github.com/pingcap/tidb/issues/50043) [#51324](https://github.com/pingcap/tidb/issues/51324) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that TiDB does not listen to the corresponding port when `force-init-stats` is configured [#51473](https://github.com/pingcap/tidb/issues/51473) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the query result is incorrect when the `IN()` predicate contains `NULL` [#51560](https://github.com/pingcap/tidb/issues/51560) @[winoros](https://github.com/winoros) + - Fix the issue that the TiDB synchronously loading statistics mechanism retries to load empty statistics indefinitely and prints the `fail to get stats version for this histogram` log [#52657](https://github.com/pingcap/tidb/issues/52657) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `EXCHANGE PARTITION` incorrectly processes foreign keys [#51807](https://github.com/pingcap/tidb/issues/51807) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `LIMIT` might not be pushed down to the `OR` type `Index Merge` [#48588](https://github.com/pingcap/tidb/issues/48588) @[AilinKid](https://github.com/AilinKid) + - Fix the incorrect result of the TopN operator in correlated subqueries [#52777](https://github.com/pingcap/tidb/issues/52777) @[yibin87](https://github.com/yibin87) + - Fix the issue that the `CPS by type` metric displays incorrect values [#52605](https://github.com/pingcap/tidb/issues/52605) @[nolouch](https://github.com/nolouch) + - Fix the issue that the `EXPLAIN` statement might display incorrect column IDs in the result when statistics for certain columns are not fully loaded [#52207](https://github.com/pingcap/tidb/issues/52207) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that expressions containing different collations might cause the query to panic when the new framework for collations is disabled [#52772](https://github.com/pingcap/tidb/issues/52772) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that executing SQL statements containing tables with multi-valued indexes might return the `Can't find a proper physical plan for this query` error [#49438](https://github.com/pingcap/tidb/issues/49438) @[qw4990](https://github.com/qw4990) + - Fix the issue that TiDB cannot correctly convert the type of a system variable in an expression [#43527](https://github.com/pingcap/tidb/issues/43527) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that executing `INSERT IGNORE` might result in inconsistency between the unique index and the data [#51784](https://github.com/pingcap/tidb/issues/51784) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that automatic statistics collection gets stuck after an OOM error occurs [#51993](https://github.com/pingcap/tidb/issues/51993) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiDB might crash when `tidb_mem_quota_analyze` is enabled and the memory used by updating statistics exceeds the limit [#52601](https://github.com/pingcap/tidb/issues/52601) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `max_execute_time` settings at multiple levels interfere with each other [#50914](https://github.com/pingcap/tidb/issues/50914) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue of index inconsistency caused by adding multiple indexes using a single SQL statement [#51746](https://github.com/pingcap/tidb/issues/51746) @[tangenta](https://github.com/tangenta) + - Fix the issue that the Window function might panic when there is a related subquery in it [#42734](https://github.com/pingcap/tidb/issues/42734) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiDB crashes when `shuffleExec` quits unexpectedly [#48230](https://github.com/pingcap/tidb/issues/48230) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the status gets stuck when rolling back the partition DDL tasks [#51090](https://github.com/pingcap/tidb/issues/51090) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that querying JSON of `BINARY` type might cause an error in some cases [#51547](https://github.com/pingcap/tidb/issues/51547) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that adding indexes to large tables fails after enabling the Distributed eXecution Framework (DXF) [#52640](https://github.com/pingcap/tidb/issues/52640) @[tangenta](https://github.com/tangenta) + - Fix the issue that the TTL feature causes data hotspots due to incorrect data range splitting in some cases [#51527](https://github.com/pingcap/tidb/issues/51527) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that `ALTER TABLE ... COMPACT TIFLASH REPLICA` might incorrectly end when the primary key type is `VARCHAR` [#51810](https://github.com/pingcap/tidb/issues/51810) @[breezewish](https://github.com/breezewish) + - Fix the issue of inconsistent data indexes caused by cluster upgrade during adding indexes [#52411](https://github.com/pingcap/tidb/issues/52411) @[tangenta](https://github.com/tangenta) + - Fix the performance regression issue caused by disabling predicate pushdown in TableDual [#50614](https://github.com/pingcap/tidb/issues/50614) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that the TiDB server adds a label via the HTTP interface and returns success, but does not take effect [#51427](https://github.com/pingcap/tidb/issues/51427) @[you06](https://github.com/you06) + - Fix the issue that adding indexes in the ingest mode might cause inconsistent data index in some corner cases [#51954](https://github.com/pingcap/tidb/issues/51954) @[lance6716](https://github.com/lance6716) + - Fix the issue that the `init-stats` process might cause TiDB to panic and the `load stats` process to quit [#51581](https://github.com/pingcap/tidb/issues/51581) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the configuration file does not take effect when it contains an invalid configuration item [#51399](https://github.com/pingcap/tidb/issues/51399) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that query execution using MPP might lead to incorrect query results when a SQL statement contains `JOIN` and the `SELECT` list in the statement contains only constants [#50358](https://github.com/pingcap/tidb/issues/50358) @[yibin87](https://github.com/yibin87) + - Fix the issue that in `determinate` mode (`tidb_opt_objective='determinate'`), if a query does not contain predicates, statistics might not be loaded [#48257](https://github.com/pingcap/tidb/issues/48257) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that the `SURVIVAL_PREFERENCES` attribute might not appear in the output of the `SHOW CREATE PLACEMENT POLICY` statement under certain conditions [#51699](https://github.com/pingcap/tidb/issues/51699) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that IndexJoin produces duplicate rows when calculating hash values in the Left Outer Anti Semi type [#52902](https://github.com/pingcap/tidb/issues/52902) @[yibin87](https://github.com/yibin87) + - Fix the issue that the `TIMESTAMPADD()` function returns incorrect results [#41052](https://github.com/pingcap/tidb/issues/41052) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that data conversion from the `FLOAT` type to the `UNSIGNED` type returns incorrect results [#41736](https://github.com/pingcap/tidb/issues/41736) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the `TRUNCATE()` function returns incorrect results when its second argument is a large negative number [#52978](https://github.com/pingcap/tidb/issues/52978) @[yibin87](https://github.com/yibin87) + - Fix the issue that duplicated panel IDs in Grafana might cause abnormal display [#51556](https://github.com/pingcap/tidb/issues/51556) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that TiDB unexpectedly restarts when logging gRPC errors [#51301](https://github.com/pingcap/tidb/issues/51301) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiDB loading statistics during startup might cause OOM [#52219](https://github.com/pingcap/tidb/issues/52219) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the TTL job for a table does not stop after the table is deleted [#51540](https://github.com/pingcap/tidb/issues/51540) @[YangKeao](https://github.com/YangKeao) + ++ TiKV + + - Fix the issue that `thread_id` values are incorrectly displayed as `0x5` in TiKV logs [#16398](https://github.com/tikv/tikv/issues/16398) @[overvenus](https://github.com/overvenus) + - Fix the issue of unstable test cases, ensuring that each test uses an independent temporary directory to avoid online configuration changes affecting other test cases [#16871](https://github.com/tikv/tikv/issues/16871) @[glorv](https://github.com/glorv) + - Fix the issue that TiKV might panic during the conversion from Binary to JSON [#16616](https://github.com/tikv/tikv/issues/16616) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the output of the `raft region` command in tikv-ctl does not include the Region status information [#17037](https://github.com/tikv/tikv/issues/17037) @[glorv](https://github.com/glorv) + - Fix the issue that slow `check-leader` operations on one TiKV node cause `resolved-ts` on other TiKV nodes to fail to advance normally [#15999](https://github.com/tikv/tikv/issues/15999) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that after the process of destroying Peer is interrupted by applying snapshots, it does not resume even after applying snapshots is complete [#16561](https://github.com/tikv/tikv/issues/16561) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that the decimal part of the `DECIMAL` type is incorrect in some cases [#16913](https://github.com/tikv/tikv/issues/16913) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that the `CONV()` function in queries might overflow during numeric system conversion, leading to TiKV panic [#16969](https://github.com/tikv/tikv/issues/16969) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that TiKV converts the time zone incorrectly for Brazil and Egypt [#16220](https://github.com/tikv/tikv/issues/16220) @[overvenus](https://github.com/overvenus) + - Fix the issue that the monitoring metric `tikv_unified_read_pool_thread_count` has no data in some cases [#16629](https://github.com/tikv/tikv/issues/16629) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that inactive Write Ahead Logs (WALs) in RocksDB might corrupt data [#16705](https://github.com/tikv/tikv/issues/16705) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that resolve-ts is blocked when a stale Region peer ignores the GC message [#16504](https://github.com/tikv/tikv/issues/16504) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that during the execution of an optimistic transaction, if other transactions initiate the resolving lock operation on it, there is a small chance that the atomicity of the transaction might be broken if the transaction's primary key has data that was previously committed in Async Commit or 1PC mode [#16620](https://github.com/tikv/tikv/issues/16620) @[MyonKeminta](https://github.com/MyonKeminta) + ++ PD + + - Fix the issue of connection panic after fault recovery in the TiDB network partition [#7926](https://github.com/tikv/pd/issues/7926) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that scheduling might be incorrectly paused after online data recovery [#8095](https://github.com/tikv/pd/issues/8095) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the CPS By Type monitoring types display incorrectly after enabling resource groups [#52605](https://github.com/pingcap/tidb/issues/52605) @[nolouch](https://github.com/nolouch) + - Fix the issue that changing the log level via the configuration file does not take effect [#8117](https://github.com/tikv/pd/issues/8117) @[rleungx](https://github.com/rleungx) + - Fix the issue that a large number of retries occur when canceling resource groups queries [#8217](https://github.com/tikv/pd/issues/8217) @[nolouch](https://github.com/nolouch) + - Fix the issue that `ALTER PLACEMENT POLICY` cannot modify the placement policy [#52257](https://github.com/pingcap/tidb/issues/52257) [#51712](https://github.com/pingcap/tidb/issues/51712) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that down peers might not recover when using Placement Rules [#7808](https://github.com/tikv/pd/issues/7808) @[rleungx](https://github.com/rleungx) + - Fix the issue that manually transferring the PD leader might fail [#8225](https://github.com/tikv/pd/issues/8225) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the scheduling of write hotspots might break placement policy constraints [#7848](https://github.com/tikv/pd/issues/7848) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that slots are not fully deleted in a resource group client, which causes the number of the allocated tokens to be less than the specified value [#7346](https://github.com/tikv/pd/issues/7346) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the scaling progress is not correctly displayed [#7726](https://github.com/tikv/pd/issues/7726) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that the Leader fails to transfer when you switch it between two deployed data centers [#7992](https://github.com/tikv/pd/issues/7992) @[TonsnakeLin](https://github.com/TonsnakeLin) + - Fix the issue that the `Filter target` monitoring metric for PD does not provide scatter range information [#8125](https://github.com/tikv/pd/issues/8125) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the query result of `SHOW CONFIG` includes the deprecated configuration item `trace-region-flow` [#7917](https://github.com/tikv/pd/issues/7917) @[rleungx](https://github.com/rleungx) + ++ TiFlash + + - Fix the issue that in the disaggregated storage and compute architecture, null values might be incorrectly returned in queries after adding non-null columns in DDL operations [#9084](https://github.com/pingcap/tiflash/issues/9084) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue of query timeout when executing queries on partitioned tables that contain empty partitions [#9024](https://github.com/pingcap/tiflash/issues/9024) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that in the disaggregated storage and compute architecture, TiFlash might panic when the compute node process is stopped [#8860](https://github.com/pingcap/tiflash/issues/8860) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that querying generated columns returns an error [#8787](https://github.com/pingcap/tiflash/issues/8787) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiFlash metadata might become corrupted and cause the process to panic when upgrading a cluster from a version earlier than v6.5.0 to v6.5.0 or later [#9039](https://github.com/pingcap/tiflash/issues/9039) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that the `ENUM` column might cause TiFlash to crash during chunk encoding [#8674](https://github.com/pingcap/tiflash/issues/8674) @[yibin87](https://github.com/yibin87) + - Fix incorrect `local_region_num` values in logs [#8895](https://github.com/pingcap/tiflash/issues/8895) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that in the disaggregated storage and compute architecture, TiFlash might panic during shutdown [#8837](https://github.com/pingcap/tiflash/issues/8837) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might return transiently incorrect results in high-concurrency read scenarios [#8845](https://github.com/pingcap/tiflash/issues/8845) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that in the disaggregated storage and compute architecture, the disk `used_size` metric displayed in Grafana is incorrect after you modify the value of the `storage.remote.cache.capacity` configuration item for TiFlash compute nodes [#8920](https://github.com/pingcap/tiflash/issues/8920) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that in the disaggregated storage and compute architecture, queries might be permanently blocked after network isolation [#8806](https://github.com/pingcap/tiflash/issues/8806) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that TiFlash might panic when you insert data to columns with invalid default values in non-strict `sql_mode` [#8803](https://github.com/pingcap/tiflash/issues/8803) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + ++ Tools + + + Backup & Restore (BR) + + - Fix a rare issue that special event timing might cause the data loss in log backup [#16739](https://github.com/tikv/tikv/issues/16739) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that too many logs are printed when a full backup fails [#51572](https://github.com/pingcap/tidb/issues/51572) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that a PD connection failure could cause the TiDB instance where the log backup advancer owner is located to panic [#52597](https://github.com/pingcap/tidb/issues/52597) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the global checkpoint of log backup is advanced ahead of the actual backup file write point due to TiKV restart, which might cause a small amount of backup data loss [#16809](https://github.com/tikv/tikv/issues/16809) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV might panic when resuming a paused log backup task with unstable network connections to PD [#17020](https://github.com/tikv/tikv/issues/17020) @[YuJuncen](https://github.com/YuJuncen) + - Fix an unstable test case [#52547](https://github.com/pingcap/tidb/issues/52547) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the Region fetched from PD does not have a Leader when restoring data using BR or importing data using TiDB Lightning in physical import mode [#51124](https://github.com/pingcap/tidb/issues/51124) [#50501](https://github.com/pingcap/tidb/issues/50501) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that TiKV panics when a full backup fails to find a peer in some extreme cases [#16394](https://github.com/tikv/tikv/issues/16394) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that removing a log backup task after it is paused does not immediately restore the GC safepoint [#52082](https://github.com/pingcap/tidb/issues/52082) @[3pointer](https://github.com/3pointer) + - Fix the unstable test case `TestClearCache` [#50743](https://github.com/pingcap/tidb/issues/50743) @[3pointer](https://github.com/3pointer) + - Fix the issue that BR fails to restore a transactional KV cluster due to an empty `EndKey` [#52574](https://github.com/pingcap/tidb/issues/52574) @[3pointer](https://github.com/3pointer) + - Fix the issue that the transfer of PD leaders might cause BR to panic when restoring data [#53724](https://github.com/pingcap/tidb/issues/53724) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that BR could not back up the `AUTO_RANDOM` ID allocation progress in a union clustered index that contains an `AUTO_RANDOM` column [#52255](https://github.com/pingcap/tidb/issues/52255) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Fix the issue that high latency in the PD disk I/O causes severe latency in data replication [#9054](https://github.com/pingcap/tiflow/issues/9054) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that calling the API (`/api/v2/owner/resign`) that evicts the TiCDC owner node causes the TiCDC task to restart unexpectedly [#10781](https://github.com/pingcap/tiflow/issues/10781) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that data is written to a wrong CSV file due to wrong BarrierTS in scenarios where DDL statements are executed frequently [#10668](https://github.com/pingcap/tiflow/issues/10668) @[lidezhu](https://github.com/lidezhu) + - Fix the issue that TiCDC fails to validate `TIMESTAMP` type checksum due to time zone mismatch after data integrity validation for single-row data is enabled [#10573](https://github.com/pingcap/tiflow/issues/10573) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that a changefeed with eventual consistency enabled might fail when the object storage sink encounters a temporary failure [#10710](https://github.com/pingcap/tiflow/issues/10710) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that `DROP PRIMARY KEY` and `DROP UNIQUE KEY` statements are not replicated correctly [#10890](https://github.com/pingcap/tiflow/issues/10890) @[asddongmen](https://github.com/asddongmen) + - Fix the issue TiCDC panics when scheduling table replication tasks [#10613](https://github.com/pingcap/tiflow/issues/10613) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that when the downstream Pulsar is stopped, removing the changefeed causes the normal TiCDC process to get stuck, which causes other changefeed processes to get stuck [#10629](https://github.com/pingcap/tiflow/issues/10629) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that restarting PD might cause the TiCDC node to restart with an error [#10799](https://github.com/pingcap/tiflow/issues/10799) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the old value part of `open-protocol` incorrectly outputs the default value according to the `STRING` type instead of its actual type [#10803](https://github.com/pingcap/tiflow/issues/10803) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the default value of `TIMEZONE` type is not set according to the correct time zone [#10931](https://github.com/pingcap/tiflow/issues/10931) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that TiCDC fails to execute the `Exchange Partition ... With Validation` DDL downstream after it is written upstream, causing the changefeed to get stuck [#10859](https://github.com/pingcap/tiflow/issues/10859) @[hongyunyan](https://github.com/hongyunyan) + - Fix the issue that data race in the KV client causes TiCDC to panic [#10718](https://github.com/pingcap/tiflow/issues/10718) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that updating the primary key or the unique key in upstream might cause data inconsistency between upstream and downstream [#10918](https://github.com/pingcap/tiflow/issues/10918) @[lidezhu](https://github.com/lidezhu) + + + TiDB Data Migration (DM) + + - Fix the connection blocking issue by upgrading `go-mysql` [#11041](https://github.com/pingcap/tiflow/issues/11041) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that data is lost when the upstream primary key is of binary type [#10672](https://github.com/pingcap/tiflow/issues/10672) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning might fail to import data when EBS BR is running [#49517](https://github.com/pingcap/tidb/issues/49517) @[mittalrishabh](https://github.com/mittalrishabh) + - Fix the issue that TiDB Lightning reports `no database selected` during data import due to incompatible SQL statements in the source files [#51800](https://github.com/pingcap/tidb/issues/51800) @[lance6716](https://github.com/lance6716) + - Fix the issue that killing the PD Leader causes TiDB Lightning to report the `invalid store ID 0` error during data import [#50501](https://github.com/pingcap/tidb/issues/50501) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that TiDB Lightning panics when importing an empty table of Parquet format [#52518](https://github.com/pingcap/tidb/issues/52518) @[kennytm](https://github.com/kennytm) diff --git a/releases/release-7.5.3.md b/releases/release-7.5.3.md new file mode 100644 index 0000000000000..f635f9d5e0983 --- /dev/null +++ b/releases/release-7.5.3.md @@ -0,0 +1,130 @@ +--- +title: TiDB 7.5.3 Release Notes +summary: Learn about the compatibility changes, improvements, and bug fixes in TiDB 7.5.3. +--- + +# TiDB 7.5.3 Release Notes + +Release date: August 5, 2024 + +TiDB version: 7.5.3 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.5/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v7.5/production-deployment-using-tiup) + +## Compatibility changes + +- Add a new system table [`INFORMATION_SCHEMA.KEYWORDS`](/information-schema/information-schema-keywords.md) to display the information of all keywords supported by TiDB [#48801](https://github.com/pingcap/tidb/issues/48801) @[dveeden](https://github.com/dveeden) + +## Improvements + ++ TiDB + + - By batch deleting TiFlash placement rules, improve the processing speed of data GC after performing the `TRUNCATE` or `DROP` operation on partitioned tables [#54068](https://github.com/pingcap/tidb/issues/54068) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + ++ TiFlash + + - Mitigate the issue that TiFlash might panic due to updating certificates after TLS is enabled [#8535](https://github.com/pingcap/tiflash/issues/8535) @[windtalker](https://github.com/windtalker) + - Reduce lock conflicts under highly concurrent data read operations and optimize short query performance [#9125](https://github.com/pingcap/tiflash/issues/9125) @[JinheLin](https://github.com/JinheLin) + ++ Tools + + + Backup & Restore (BR) + + - Except for the `br log restore` subcommand, all other `br log` subcommands support skipping the loading of the TiDB `domain` data structure to reduce memory consumption [#52088](https://github.com/pingcap/tidb/issues/52088) @[Leavrth](https://github.com/Leavrth) + - Support automatically abandoning log backup tasks when encountering a large checkpoint lag, to avoid prolonged blocking GC and potential cluster issues [#50803](https://github.com/pingcap/tidb/issues/50803) @[RidRisR](https://github.com/RidRisR) + - Increase the number of retries for failures caused by DNS errors [#53029](https://github.com/pingcap/tidb/issues/53029) @[YuJuncen](https://github.com/YuJuncen) + - Add PITR integration test cases to cover compatibility testing for log backup and adding index acceleration [#51987](https://github.com/pingcap/tidb/issues/51987) @[Leavrth](https://github.com/Leavrth) + - Increase the number of retries for failures caused by the absence of a leader in a Region [#54017](https://github.com/pingcap/tidb/issues/54017) @[Leavrth](https://github.com/Leavrth) + - Support setting Alibaba Cloud access credentials through environment variables [#45551](https://github.com/pingcap/tidb/issues/45551) @[RidRisR](https://github.com/RidRisR) + + + TiCDC + + - Support directly outputting raw events when the downstream is a Message Queue (MQ) or cloud storage [#11211](https://github.com/pingcap/tiflow/issues/11211) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Bug fixes + ++ TiDB + + - Fix the issue that loading index statistics might cause memory leaks [#54022](https://github.com/pingcap/tidb/issues/54022) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `UPDATE` operation can cause TiDB OOM in multi-table scenarios [#53742](https://github.com/pingcap/tidb/issues/53742) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that indirect placeholder `?` references in a `GROUP BY` statement cannot find columns [#53872](https://github.com/pingcap/tidb/issues/53872) @[qw4990](https://github.com/qw4990) + - Fix the issue that the `LENGTH()` condition is unexpectedly removed when the collation is `utf8_bin` or `utf8mb4_bin` [#53730](https://github.com/pingcap/tidb/issues/53730) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that inserting an overlarge number in scientific notation returns a warning instead of an error, making it consistent with MySQL [#47787](https://github.com/pingcap/tidb/issues/47787) @[qw4990](https://github.com/qw4990) + - Fix the issue that recursive CTE queries might result in invalid pointers [#54449](https://github.com/pingcap/tidb/issues/54449) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that statistics collection does not update the `stats_history` table when encountering duplicate primary keys [#47539](https://github.com/pingcap/tidb/issues/47539) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that when queries contain non-correlated subqueries and `LIMIT` clauses, column pruning might be incomplete, resulting in a less optimal plan [#54213](https://github.com/pingcap/tidb/issues/54213) @[qw4990](https://github.com/qw4990) + - Fix the issue of abnormally high memory usage caused by `memTracker` not being detached when the `HashJoin` or `IndexLookUp` operator is the driven side sub-node of the `Apply` operator [#54005](https://github.com/pingcap/tidb/issues/54005) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that the recursive CTE operator incorrectly tracks memory usage [#54181](https://github.com/pingcap/tidb/issues/54181) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that the memory used by transactions might be tracked multiple times [#53984](https://github.com/pingcap/tidb/issues/53984) @[ekexium](https://github.com/ekexium) + - Fix the issue that using `SHOW WARNINGS;` to obtain warnings might cause a panic [#48756](https://github.com/pingcap/tidb/issues/48756) @[xhebox](https://github.com/xhebox) + - Fix the issue that updating an `UNSIGNED` type of field to `-1` returns `null` instead of `0` when `sql_mode=''` [#47816](https://github.com/pingcap/tidb/issues/47816) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the `TIMESTAMPADD()` function goes into an infinite loop when the first argument is `month` and the second argument is negative [#54908](https://github.com/pingcap/tidb/issues/54908) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that the Connection Count monitoring metric in Grafana is incorrect when some connections exit before the handshake is complete [#54428](https://github.com/pingcap/tidb/issues/54428) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the Connection Count of each resource group is incorrect when using TiProxy and resource groups [#54545](https://github.com/pingcap/tidb/issues/54545) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that executing `CREATE OR REPLACE VIEW` concurrently might result in the `table doesn't exist` error [#53673](https://github.com/pingcap/tidb/issues/53673) @[tangenta](https://github.com/tangenta) + - Fix the issue that TiDB might return incorrect query results when you query tables with virtual columns in transactions that involve data modification operations [#53951](https://github.com/pingcap/tidb/issues/53951) @[qw4990](https://github.com/qw4990) + - Fix the issue that executing the `SELECT DISTINCT CAST(col AS DECIMAL), CAST(col AS SIGNED) FROM ...` query might return incorrect results [#53726](https://github.com/pingcap/tidb/issues/53726) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue of incorrect WARNINGS information when using Optimizer Hints [#53767](https://github.com/pingcap/tidb/issues/53767) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the illegal column type `DECIMAL(0,0)` can be created in some cases [#53779](https://github.com/pingcap/tidb/issues/53779) @[tangenta](https://github.com/tangenta) + - Fix the issue that the `memory_quota` hint might not work in subqueries [#53834](https://github.com/pingcap/tidb/issues/53834) @[qw4990](https://github.com/qw4990) + - Fix the issue that JSON-related functions return errors inconsistent with MySQL in some cases [#53799](https://github.com/pingcap/tidb/issues/53799) @[dveeden](https://github.com/dveeden) + - Fix the issue that improper use of metadata locks might lead to writing anomalous data when using the plan cache under certain circumstances [#53634](https://github.com/pingcap/tidb/issues/53634) @[zimulala](https://github.com/zimulala) + - Fix the issue that certain filter conditions in queries might cause the planner module to report an `invalid memory address or nil pointer dereference` error [#53582](https://github.com/pingcap/tidb/issues/53582) [#53580](https://github.com/pingcap/tidb/issues/53580) [#53594](https://github.com/pingcap/tidb/issues/53594) [#53603](https://github.com/pingcap/tidb/issues/53603) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that after a statement within a transaction is killed by OOM, if TiDB continues to execute the next statement within the same transaction, you might get an error `Trying to start aggressive locking while it's already started` and a panic occurs [#53540](https://github.com/pingcap/tidb/issues/53540) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that executing `ALTER TABLE ... REMOVE PARTITIONING` might cause data loss [#53385](https://github.com/pingcap/tidb/issues/53385) @[mjonss](https://github.com/mjonss) + - Fix the issue that `PREPARE`/`EXECUTE` statements with the `CONV` expression containing a `?` argument might result in incorrect query results when executed multiple times [#53505](https://github.com/pingcap/tidb/issues/53505) @[qw4990](https://github.com/qw4990) + - Fix the issue that TiDB fails to reject unauthenticated user connections in some cases when using the `auth_socket` authentication plugin [#54031](https://github.com/pingcap/tidb/issues/54031) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the query latency of stale reads increases, caused by information schema cache misses [#53428](https://github.com/pingcap/tidb/issues/53428) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that the `STATE` field in the `INFORMATION_SCHEMA.TIDB_TRX` table is empty due to the `size` of the `STATE` field not being defined [#53026](https://github.com/pingcap/tidb/issues/53026) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that the `tidb_enable_async_merge_global_stats` and `tidb_analyze_partition_concurrency` system variables do not take effect during automatic statistics collection [#53972](https://github.com/pingcap/tidb/issues/53972) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that using `CURRENT_DATE()` as the default value for a column results in incorrect query results [#53746](https://github.com/pingcap/tidb/issues/53746) @[tangenta](https://github.com/tangenta) + - Fix the issue of reusing wrong point get plans for `SELECT ... FOR UPDATE` [#54652](https://github.com/pingcap/tidb/issues/54652) @[qw4990](https://github.com/qw4990) + ++ TiKV + + - Fix the issue that setting the gRPC message compression method via `grpc-compression-type` does not take effect on messages sent from TiKV to TiDB [#17176](https://github.com/tikv/tikv/issues/17176) @[ekexium](https://github.com/ekexium) + - Fix the issue that highly concurrent Coprocessor requests might cause TiKV OOM [#16653](https://github.com/tikv/tikv/issues/16653) @[overvenus](https://github.com/overvenus) + - Fix the issue that CDC and log-backup do not limit the timeout of `check_leader` using the `advance-ts-interval` configuration, causing the `resolved_ts` lag to be too large when TiKV restarts normally in some cases [#17107](https://github.com/tikv/tikv/issues/17107) @[MyonKeminta](https://github.com/MyonKeminta) + - Fix the issue that TiKV might repeatedly panic when applying a corrupted Raft data snapshot [#15292](https://github.com/tikv/tikv/issues/15292) @[LykxSassinator](https://github.com/LykxSassinator) + ++ PD + + - Fix the issue that slots are not fully deleted in a resource group client, which causes the number of the allocated tokens to be less than the specified value [#7346](https://github.com/tikv/pd/issues/7346) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that a resource group encounters quota limits when requesting tokens for more than 500 ms [#8349](https://github.com/tikv/pd/issues/8349) @[nolouch](https://github.com/nolouch) + - Fix the data race issue of resource groups [#8267](https://github.com/tikv/pd/issues/8267) @[HuSharp](https://github.com/HuSharp) + - Fix the data race issue that PD encounters during operator checks [#8263](https://github.com/tikv/pd/issues/8263) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that deleted nodes still appear in the candidate connection list in etcd client [#8286](https://github.com/tikv/pd/issues/8286) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that setting the TiKV configuration item [`coprocessor.region-split-size`](/tikv-configuration-file.md#region-split-size) to a value less than 1 MiB causes PD panic [#8323](https://github.com/tikv/pd/issues/8323) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the encryption manager is not initialized before use [#8384](https://github.com/tikv/pd/issues/8384) @[releungx](https://github.com/releungx) + - Fix the issue that PD logs are not fully redacted when the PD configuration item [`security.redact-info-log`](/pd-configuration-file.md#redact-info-log-new-in-v50) is enabled [#8419](https://github.com/tikv/pd/issues/8419) @[releungx](https://github.com/releungx) + - Fix the issue that no error is reported when binding a role to a resource group [#54417](https://github.com/pingcap/tidb/issues/54417) @[JmPotato](https://github.com/JmPotato) + ++ TiFlash + + - Fix the issue that a large number of duplicate rows might be read in FastScan mode after importing data via BR or TiDB Lightning [#9118](https://github.com/pingcap/tiflash/issues/9118) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that the `SUBSTRING_INDEX()` function might cause TiFlash to crash in some corner cases [#9116](https://github.com/pingcap/tiflash/issues/9116) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that setting the SSL certificate configuration to an empty string in TiFlash incorrectly enables TLS and causes TiFlash to fail to start [#9235](https://github.com/pingcap/tiflash/issues/9235) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that some queries might report a column type mismatch error after late materialization is enabled [#9175](https://github.com/pingcap/tiflash/issues/9175) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that queries with virtual generated columns might return incorrect results after late materialization is enabled [#9188](https://github.com/pingcap/tiflash/issues/9188) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that TiFlash might panic after executing `RENAME TABLE ... TO ...` on a partitioned table with empty partitions across databases [#9132](https://github.com/pingcap/tiflash/issues/9132) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might panic when a database is deleted shortly after creation [#9266](https://github.com/pingcap/tiflash/issues/9266) @[JaySon-Huang](https://github.com/JaySon-Huang) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that log backup might be paused after the advancer owner migration [#53561](https://github.com/pingcap/tidb/issues/53561) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that BR fails to correctly identify errors due to multiple nested retries during the restore process [#54053](https://github.com/pingcap/tidb/issues/54053) @[RidRisR](https://github.com/RidRisR) + - Fix the inefficiency issue in scanning DDL jobs during incremental backups [#54139](https://github.com/pingcap/tidb/issues/54139) @[3pointer](https://github.com/3pointer) + - Fix the issue that the backup performance during checkpoint backups is affected due to interruptions in seeking Region leaders [#17168](https://github.com/tikv/tikv/issues/17168) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that after pausing, stopping, and rebuilding the log backup task, the task status is normal, but the checkpoint does not advance [#53047](https://github.com/pingcap/tidb/issues/53047) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that DDLs requiring backfilling, such as `ADD INDEX` and `MODIFY COLUMN`, might not be correctly recovered during incremental restore [#54426](https://github.com/pingcap/tidb/issues/54426) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Fix the issue that the checksum is not correctly set to `0` after splitting `UPDATE` events [#11402](https://github.com/pingcap/tiflow/issues/11402) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the Processor module might get stuck when the downstream Kafka is inaccessible [#11340](https://github.com/pingcap/tiflow/issues/11340) @[asddongmen](https://github.com/asddongmen) + + + Dumpling + + - Fix the issue that Dumpling reports an error when exporting tables and views at the same time [#53682](https://github.com/pingcap/tidb/issues/53682) @[tangenta](https://github.com/tangenta) diff --git a/releases/release-7.6.0.md b/releases/release-7.6.0.md new file mode 100644 index 0000000000000..2085468ad58da --- /dev/null +++ b/releases/release-7.6.0.md @@ -0,0 +1,542 @@ +--- +title: TiDB 7.6.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 7.6.0. +--- + +# TiDB 7.6.0 Release Notes + +Release date: January 25, 2024 + +TiDB version: 7.6.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v7.6/quick-start-with-tidb) + +7.6.0 introduces the following key features and improvements: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeature/EnhancementDescription
Scalability and PerformanceCross-database SQL bindingWhen managing hundreds of databases with the same schema, it is often necessary to apply SQL bindings across these databases. For example, in SaaS or PaaS data platforms, each user typically operates separate databases with the same schema and runs similar SQL queries on them. In this case, it is impractical to bind SQL for each database one by one. TiDB v7.6.0 introduces cross-database SQL bindings that enable matching bindings across all schema-equivalent databases.
Achieve up to 10 times faster for snapshot restore (experimental)BR v7.6.0 introduces an experimental coarse-grained Region scatter algorithm to accelerate snapshot restores for clusters. In clusters with many TiKV nodes, this algorithm significantly improves cluster resource efficiency by more evenly distributing load across nodes and better utilizing per-node network bandwidth. In several real-world cases, this improvement accelerates restore process by about up to 10 times.
Achieve up to 10 times faster for creating tables in batch (experimental)With the implementation of the new DDL architecture in v7.6.0, the performance of batch table creation has witnessed a remarkable improvement, up to 10 times faster. This substantial enhancement drastically reduces the time needed for creating numerous tables. This acceleration is particularly noteworthy in SaaS scenarios, where the prevalence of high volumes of tables, ranging from tens to hundreds of thousands, is a common challenge.
Use Active PD Followers to enhance PD's Region information query service (experimental)TiDB v7.6.0 introduces an experimental feature "Active PD Follower", which allows PD followers to provide Region information query services. This feature improves the capability of the PD cluster to handle GetRegion and ScanRegions requests in clusters with a large number of TiDB nodes and Regions, thereby reducing the CPU pressure on the PD leader.
Reliability and AvailabilitySupport TiProxy (experimental)Full support for the TiProxy service, easily deployable via deployment tooling, to manage and maintain connections to TiDB so that they live through rolling restarts, upgrades, or scaling events.
Data Migration (DM) officially supports MySQL 8.0 (GA)Previously, using DM to migrate data from MySQL 8.0 is an experimental feature and is not available for production environments. TiDB v7.6.0 enhances the stability and compatibility of this feature to help you smoothly and quickly migrate data from MySQL 8.0 to TiDB in production environments. In v7.6.0, this feature becomes generally available (GA).
+ +## Feature details + +### Scalability + +* Use the Active PD Follower feature to enhance the scalability of PD's Region information query service (experimental) [#7431](https://github.com/tikv/pd/issues/7431) @[CabinfeverB](https://github.com/CabinfeverB) + + In a TiDB cluster with a large number of Regions, the PD leader might experience high CPU load due to the increased overhead of handling heartbeats and scheduling tasks. If the cluster has many TiDB instances, and there is a high concurrency of requests for Region information, the CPU pressure on the PD leader increases further and might cause PD services to become unavailable. + + To ensure high availability, TiDB v7.6.0 supports using the Active PD Follower feature to enhance the scalability of PD's Region information query service. You can enable the Active PD Follower feature by setting the system variable [`pd_enable_follower_handle_region`](/system-variables.md#pd_enable_follower_handle_region-new-in-v760) to `ON`. After this feature is enabled, TiDB evenly distributes Region information requests to all PD servers, and PD followers can also handle Region requests, thereby reducing the CPU pressure on the PD leader. + + For more information, see [documentation](/tune-region-performance.md#use-the-active-pd-follower-feature-to-enhance-the-scalability-of-pds-region-information-query-service). + +### Performance + +* BR improves snapshot restore speed by up to 10 times (experimental) [#33937](https://github.com/pingcap/tidb/issues/33937) [#49886](https://github.com/pingcap/tidb/issues/49886) @[3pointer](https://github.com/3pointer) + + As a TiDB cluster scales up, it becomes increasingly crucial to quickly restore the cluster from failures to minimize business downtime. Before v7.6.0, the Region scattering algorithm is a primary bottleneck in performance restoration. In v7.6.0, BR optimizes the Region scattering algorithm, which quickly splits the restore task into a large number of small tasks and scatters them to all TiKV nodes in batches. The new parallel recovery algorithm fully utilizes the resources of each TiKV node, thereby achieving a rapid parallel recovery. In several real-world cases, the snapshot restore speed of the cluster is improved by about 10 times in large-scale Region scenarios. + + The new coarse-grained Region scatter algorithm is experimental. To use it, you can configure the `--granularity="coarse-grained"` parameter in the `br` command. For example: + + ```bash + br restore full \ + --pd "${PDIP}:2379" \ + --storage "s3://${Bucket}/${Folder}" \ + --s3.region "${region}" \ + --granularity "coarse-grained" \ + --send-credentials-to-tikv=true \ + --log-file restorefull.log + ``` + + For more information, see [documentation](/br/br-snapshot-guide.md#restore-cluster-snapshots). + +* The Titan engine is enabled by default [#16245](https://github.com/tikv/tikv/issues/16245) @[Connor1996](https://github.com/Connor1996) @[v01dstar](https://github.com/v01dstar) @[tonyxuqqi](https://github.com/tonyxuqqi) + + To better support TiDB wide table write scenarios, especially with support for JSON, starting from TiDB v7.6.0, the Titan engine is enabled by default. The Titan engine automatically segregates large values exceeding 32 KB from RocksDB's LSM Tree, and stores them separately in Titan to optimize the handling of large values. The Titan engine is completely compatible with RocksDB features utilized by TiKV. This strategic shift not only diminishes write amplification effect, but also enhances performance in write, update, and point-query scenarios involving large values. Additionally, in Range Scan scenarios, the Titan engine's optimization has resulted in performance comparable to that of RocksDB in the default configuration. + + This configuration change remains compatible with earlier versions. For existing TiDB clusters, when upgrading to TiDB v7.6.0 or a later version, the Titan engine is disabled by default. You have the flexibility to manually enable or disable the Titan engine based on your specific requirements. + + For more information, see [documentation](/storage-engine/titan-overview.md). + +* Support pushing down the following string functions to TiKV [#48170](https://github.com/pingcap/tidb/issues/48170) @[gengliqi](https://github.com/gengliqi) + + * `LOWER()` + * `UPPER()` + + For more information, see [documentation](/functions-and-operators/expressions-pushed-down.md). + +* Support pushing down the following JSON functions to TiFlash [#48350](https://github.com/pingcap/tidb/issues/48350) [#48986](https://github.com/pingcap/tidb/issues/48986) [#48994](https://github.com/pingcap/tidb/issues/48994) [#49345](https://github.com/pingcap/tidb/issues/49345) [#49392](https://github.com/pingcap/tidb/issues/49392) @[SeaRise](https://github.com/SeaRise) @[yibin87](https://github.com/yibin87) + + * `JSON_UNQUOTE()` + * `JSON_ARRAY()` + * `JSON_DEPTH()` + * `JSON_VALID()` + * `JSON_KEYS()` + * `JSON_CONTAINS_PATH()` + + For more information, see [documentation](/tiflash/tiflash-supported-pushdown-calculations.md). + +* Improve the performance of creating tables by 10 times (experimental) [#49752](https://github.com/pingcap/tidb/issues/49752) @[gmhdbjd](https://github.com/gmhdbjd) + + In previous versions, when migrating tens of thousands of tables from the upstream database to TiDB, it is time-consuming and inefficient for TiDB to create these tables. Starting from v7.6.0, TiDB introduces a new TiDB DDL V2 architecture. You can enable it by configuring the system variable [`tidb_ddl_version`](https://docs.pingcap.com/tidb/v7.6/system-variables#tidb_ddl_version-new-in-v760). Compared with previous versions, the new version of the DDL improves the performance of creating batch tables by 10 times, and significantly reduces time for creating tables. + + For more information, see [documentation](https://docs.pingcap.com/tidb/v7.6/ddl-v2). + +* Support periodic full compaction (experimental) [#12729](https://github.com/tikv/tikv/issues/12729) [afeinberg](https://github.com/afeinberg) + + Starting from v7.6.0, TiDB supports periodic full compaction for TiKV. This feature serves as an enhancement to Garbage Collection (GC) to eliminate redundant data versions. In scenarios where application activity shows obvious peaks and valleys, you can use this feature to perform data compaction during idle periods to improve the performance during peak periods. + + You can set the specific times that TiKV initiates periodic full compaction by configuring the TiKV configuration item [`periodic-full-compact-start-times`](/tikv-configuration-file.md#periodic-full-compact-start-times-new-in-v760) and limit the maximum CPU usage rate for TiKV periodic full compaction by configuring [`periodic-full-compact-start-max-cpu`](/tikv-configuration-file.md#periodic-full-compact-start-max-cpu-new-in-v760). The default value of `periodic-full-compact-start-max-cpu` is 10%, which means that periodic full compaction is triggered only when the CPU utilization of TiKV is lower than 10%, thereby reducing the impact on application traffic. + + For more information, see [documentation](/tikv-configuration-file.md#periodic-full-compact-start-times-new-in-v760). + +### Reliability + +* Cross-database execution plan binding [#48875](https://github.com/pingcap/tidb/issues/48875) @[qw4990](https://github.com/qw4990) + + When running SaaS services on TiDB, it is common practice to store data for each tenant in separate databases for easier data maintenance and management. This results in hundreds of databases with the same table and index definitions, and similar SQL statements. In such scenario, when you create an execution plan binding for a SQL statement, this binding usually applies to the SQL statements in other databases as well. + + For this scenario, TiDB v7.6.0 introduces the cross-database binding feature, which supports binding the same execution plan to SQL statements with the same schema, even if they are in different databases. When creating a cross-database binding, you need to use the wildcard `*` to represent the database name, as shown in the following example. After the binding is created, regardless of which database the tables `t1` and `t2` are in, TiDB will try to use this binding to generate an execution plan for any SQL statement with the same schema, which saves your effort to create a binding for each database. + + ```sql + CREATE GLOBAL BINDING FOR + USING + SELECT /*+ merge_join(t1, t2) */ t1.id, t2.amount + FROM *.t1, *.t2 + WHERE t1.id = t2.id; + ``` + + In addition, cross-database binding can effectively mitigate SQL performance issues caused by uneven distribution and rapid changes in user data and workload. SaaS providers can use cross-database binding to fix execution plans validated by users with large data volumes, thereby fixing execution plans for all users. For SaaS providers, this feature provides significant convenience and experience improvements. + + Due to the system overhead (less than 1%) introduced by cross-database binding, TiDB disables this feature by default. To use cross-database binding, you need to first enable the [`tidb_opt_enable_fuzzy_binding`](/system-variables.md#tidb_opt_enable_fuzzy_binding-new-in-v760) system variable. + + For more information, see [documentation](/sql-plan-management.md#cross-database-binding). + +### Availability + +* Support the proxy component TiProxy (experimental) [#413](https://github.com/pingcap/tiproxy/issues/413) @[djshow832](https://github.com/djshow832) @[xhebox](https://github.com/xhebox) + + TiProxy is the official proxy component of TiDB, located between the client and TiDB server. It provides load balancing and connection persistence functions for TiDB, making the workload of the TiDB cluster more balanced and not affecting user access to the database during maintenance operations. + + - During maintenance operations such as rolling restarts, rolling upgrades, and scaling-in in a TiDB cluster, changes occur in the TiDB servers which result in interruptions in connections between clients and the TiDB servers. By using TiProxy, connections can be smoothly migrated to other TiDB servers during these maintenance operations so that clients are not affected. + - Client connections to a TiDB server cannot be dynamically migrated to other TiDB servers. When the workload of multiple TiDB servers is unbalanced, it might result in a situation where the overall cluster resources are sufficient, but certain TiDB servers experience resource exhaustion leading to a significant increase in latency. To address this issue, TiProxy provides dynamic migration for connection, which allows connections to be migrated from one TiDB server to another without any impact on the clients, thereby achieving load balancing for the TiDB cluster. + + TiProxy has been integrated into TiUP, TiDB Operator, and TiDB Dashboard, making it easy to configure, deploy and maintain. + + For more information, see [documentation](/tiproxy/tiproxy-overview.md). + +### SQL + +* `LOAD DATA` supports explicit transactions and rollbacks [#49079](https://github.com/pingcap/tidb/pull/49079) @[ekexium](https://github.com/ekexium) + + Compared with MySQL, the transactional behavior of the `LOAD DATA` statement varies in different TiDB versions before v7.6.0, so you might need to make additional adjustments when using this statement. Specifically, before v4.0.0, `LOAD DATA` commits every 20000 rows. From v4.0.0 to v6.6.0, TiDB commits all rows in one transaction by default and also supports committing every fixed number of rows by setting the [`tidb_dml_batch_size`](/system-variables.md#tidb_dml_batch_size) system variable. Starting from v7.0.0, `tidb_dml_batch_size` no longer takes effect on `LOAD DATA` and TiDB commits all rows in one transaction. + + Starting from v7.6.0, TiDB processes `LOAD DATA` in transactions in the same way as other DML statements, especially in the same way as MySQL. The `LOAD DATA` statement in a transaction no longer automatically commits the current transaction or starts a new transaction. Moreover, you can explicitly commit or roll back the `LOAD DATA` statement in a transaction. Additionally, the `LOAD DATA` statement is affected by the TiDB transaction mode setting (optimistic or pessimistic transaction). These improvements simplify the migration process from MySQL to TiDB and offer a more unified and controllable experience for data import. + + For more information, see [documentation](/sql-statements/sql-statement-load-data.md). + +### DB operations + +* `FLASHBACK CLUSTER` supports specifying a precise TSO [#48372](https://github.com/pingcap/tidb/issues/48372) @[BornChanger](https://github.com/BornChanger/BornChanger) + + In TiDB v7.6.0, the flashback feature is more powerful and precise. It not only supports rolling back a cluster to a specified historical timestamp but also enables you to specify a precise recovery [TSO](/tso.md) using `FLASHBACK CLUSTER TO TSO`, thereby increasing flexibility in data recovery. For example, you can use this feature with TiCDC. After pausing data replication and conducting pre-online read-write tests in your downstream TiDB cluster, this feature allows the cluster to gracefully and quickly roll back to the paused TSO and continue to replicate data using TiCDC. This streamlines the pre-online validation process and simplifies data management. + + ```sql + FLASHBACK CLUSTER TO TSO 445494839813079041; + ```` + + For more information, see [documentation](/sql-statements/sql-statement-flashback-cluster.md). + +* Support automatically terminating long-running idle transactions [#48714](https://github.com/pingcap/tidb/pull/48714) @[crazycs520](https://github.com/crazycs520) + + In scenarios where network disconnection or application failure occurs, `COMMIT`/`ROLLBACK` statements might fail to be transmitted to the database. This could lead to delayed release of database locks, causing transaction lock waits and a rapid increase in database connections. Such issues are common in test environments but can also occur occasionally in production environments, and they are sometimes difficult to diagnose promptly. To avoid these issues, TiDB v7.6.0 introduces the [`tidb_idle_transaction_timeout`](/system-variables.md#tidb_idle_transaction_timeout-new-in-v760) system variable, which automatically terminates long-running idle transactions. When a user session in a transactional state remains idle for a duration exceeding the value of this variable, TiDB will terminate the database connection of the transaction and roll back it. + + For more information, see [documentation](/system-variables.md#tidb_idle_transaction_timeout-new-in-v760). + +* Simplify the syntax for creating execution plan bindings [#48876](https://github.com/pingcap/tidb/issues/48876) @[qw4990](https://github.com/qw4990) + + TiDB v7.6.0 simplifies the syntax for creating execution plan bindings. When creating an execution plan binding, you no longer need to provide the original SQL statement. TiDB identifies the original SQL statement based on the statement with hints. This improvement enhances the convenience of creating execution plan bindings. For example: + + ```sql + CREATE GLOBAL BINDING + USING + SELECT /*+ merge_join(t1, t2) */ * FROM t1, t2 WHERE t1.id = t2.id; + ``` + + For more information, see [documentation](/sql-plan-management.md#create-a-binding-according-to-a-sql-statement). + +* Support dynamically modifying the size limit of a single row record in TiDB [#49237](https://github.com/pingcap/tidb/pull/49237) @[zyguan](https://github.com/zyguan) + + Before v7.6.0, the size of a single row record in a transaction is limited by the TiDB configuration item [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500). If the size limit is exceeded, TiDB returns the `entry too large` error. In this case, you need to manually modify the TiDB configuration file and restart TiDB to make the modification take effect. To reduce your management overhead, TiDB v7.6.0 introduces the system variable [`tidb_txn_entry_size_limit`](/system-variables.md#tidb_txn_entry_size_limit-new-in-v760), which supports dynamically modifying the value of the `txn-entry-size-limit` configuration item. The default value of this variable is `0`, which means that TiDB uses the value of the configuration item `txn-entry-size-limit` by default. When this variable is set to a non-zero value, TiDB limits the size of a row record in transactions to the value of this variable. This improvement enhances the flexibility for you to adjust system configurations without restarting TiDB. + + For more information, see [documentation](/system-variables.md#tidb_txn_entry_size_limit-new-in-v760). + +* BR restores system tables by default, such as user data [#48567](https://github.com/pingcap/tidb/issues/48567) @[BornChanger](https://github.com/BornChanger) [#49627](https://github.com/pingcap/tidb/issues/49627) @[Leavrth](https://github.com/Leavrth) + + Starting from v5.1.0, when you back up snapshots, BR automatically backs up system tables in the `mysql` schema, but does not restore these system tables by default. In v6.2.0, BR adds the parameter `--with-sys-table` to support restoring data in some system tables, providing more flexibility in operations. + + To further reduce your management overhead and provide more intuitive default behavior, starting from v7.6.0, BR enables the parameter `--with-sys-table` by default. This means that BR restores some system tables by default during restoration, especially user account and table statistics data. This improvement makes backup and restore operations more intuitive, thereby reducing the burden of manual configuration and improving the overall operation experience. + + For more information, see [documentation](/br/br-snapshot-guide.md). + +### Observability + +* Enhance observability related to resource control [#49318](https://github.com/pingcap/tidb/issues/49318) @[glorv](https://github.com/glorv) @[bufferflies](https://github.com/bufferflies) @[nolouch](https://github.com/nolouch) + + As more and more users use resource groups to isolate application workloads, Resource Control provides enhanced data based on resource groups. This helps you monitor resource group workloads and settings, ensuring that you can quickly identify and accurately diagnose problems, including: + + * [Slow Queries](/identify-slow-queries.md): add the resource group name, resource unit (RU) consumption, and time for waiting for resources. + * [Statement Summary Tables](/statement-summary-tables.md): add the resource group name, RU consumption, and time for waiting for resources. + * In the system variable [`tidb_last_query_info`](/system-variables.md#tidb_last_query_info-new-in-v4014), add a new entry `ru_consumption` to indicate the consumed [RU](/tidb-resource-control.md#what-is-request-unit-ru) by SQL statements. You can use this variable to get the resource consumption of the last statement in the session. + * Add database metrics based on resource groups: QPS/TPS, execution time (P999/P99/P95), number of failures, and number of connections. + * Add the system table [`request_unit_by_group`](/mysql-schema/mysql-schema.md#system-tables-related-to-resource-control) to record the history records of daily consumed RUs of all resource groups. + + For more information, see [Identify Slow Queries](/identify-slow-queries.md), [Statement Summary Tables](/statement-summary-tables.md), and [Key Monitoring Metrics of Resource Control](/grafana-resource-control-dashboard.md). + +### Data migration + +* Data Migration (DM) support for migrating MySQL 8.0 becomes generally available (GA) [#10405](https://github.com/pingcap/tiflow/issues/10405) @[lyzx2001](https://github.com/lyzx2001) + + Previously, using DM to migrate data from MySQL 8.0 is an experimental feature and is not available for production environments. TiDB v7.6.0 enhances the stability and compatibility of this feature to help you smoothly and quickly migrate data from MySQL 8.0 to TiDB in production environments. In v7.6.0, this feature becomes generally available (GA). + + For more information, see [documentation](/dm/dm-compatibility-catalog.md). + +* TiCDC supports replicating DDL statements in bi-directional replication (BDR) mode (experimental) [#10301](https://github.com/pingcap/tiflow/issues/10301) [#48519](https://github.com/pingcap/tidb/issues/48519) @[okJiang](https://github.com/okJiang) @[asddongmen](https://github.com/asddongmen) + + Starting from v7.6.0, TiCDC supports replication of DDL statements with bi-directional replication configured. Previously, replicating DDL statements was not supported by TiCDC, so users of TiCDC's bi-directional replication had to apply DDL statements to both TiDB clusters separately. With this feature, TiCDC allows for a cluster to be assigned the `PRIMARY` BDR role, and enables the replication of DDL statements from that cluster to the downstream cluster. + + For more information, see [documentation](/ticdc/ticdc-bidirectional-replication.md). + +* TiCDC supports querying the downstream synchronization status of a changefeed [#10289](https://github.com/pingcap/tiflow/issues/10289) @[hongyunyan](https://github.com/hongyunyan) + + Starting from v7.6.0, TiCDC introduces a new API `GET /api/v2/changefeed/{changefeed_id}/synced` to query the downstream synchronization status of a specified replication task (changefeed). By using this API, you can determine whether the upstream data received by TiCDC has been synchronized to the downstream system completely. + + For more information, see [documentation](/ticdc/ticdc-open-api-v2.md#query-whether-a-specific-replication-task-is-completed). + +* TiCDC adds support for three-character delimiters with CSV output protocol [#9969](https://github.com/pingcap/tiflow/issues/9969) @[zhangjinpeng87](https://github.com/zhangjinpeng87) + + Starting from v7.6.0, you can specify the CSV output protocol delimiters as 1 to 3 characters long. With this change, you can configure TiCDC to generate file output using two-character delimiters (such as `||` or `$^`) or three-character delimiters (such as `|@|`) to separate fields in the output. + + For more information, see [documentation](/ticdc/ticdc-csv.md). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v7.5.0 to the current version (v7.6.0). If you are upgrading from v7.4.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### MySQL compatibility + +* Before TiDB v7.6.0, the `LOAD DATA` operation commits all rows in a single transaction or commits transactions in a batch, which is slightly different from MySQL behaviors. Starting from v7.6.0, TiDB processes `LOAD DATA` in transactions in the same way as MySQL. The `LOAD DATA` statement in a transaction no longer automatically commits the current transaction or starts a new transaction. Moreover, you can explicitly commit or roll back the `LOAD DATA` statement in a transaction. Additionally, the `LOAD DATA` statement is affected by the TiDB transaction mode setting (optimistic or pessimistic transaction). [#49079](https://github.com/pingcap/tidb/pull/49079) @[ekexium](https://github.com/ekexium) + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_auto_analyze_partition_batch_size`](/system-variables.md#tidb_auto_analyze_partition_batch_size-new-in-v640) | Modified | Changes the default value from `1` to `128` after further tests. | +| [`tidb_sysproc_scan_concurrency`](/system-variables.md#tidb_sysproc_scan_concurrency-new-in-v650) | Modified | In a large-scale cluster, the concurrency of `scan` operations can be adjusted higher to meet the needs of `ANALYZE`. Therefore, change the maximum value from `256` to `4294967295`. | +| [`tidb_analyze_distsql_scan_concurrency`](/system-variables.md#tidb_analyze_distsql_scan_concurrency-new-in-v760) | Newly added | Sets the concurrency of the `scan` operation when executing the `ANALYZE` operation. The default value is `4`. | +| [`tidb_ddl_version`](https://docs.pingcap.com/tidb/v7.6/system-variables#tidb_ddl_version-new-in-v760) | Newly added | Controls whether to enable [TiDB DDL V2](https://docs.pingcap.com/tidb/v7.6/ddl-v2). Set the value to `2` to enable it and `1` to disable it. The default value is `1`. When TiDB DDL V2 is enabled, DDL statements will be executed using TiDB DDL V2. The execution speed of DDL statements for creating tables is increased by 10 times compared with TiDB DDL V1. | +| [`tidb_enable_global_index`](/system-variables.md#tidb_enable_global_index-new-in-v760) | Newly added | Controls whether to support creating `Global indexes` for partitioned tables. The default value is `OFF`. `Global index` is currently in the development stage. **It is not recommended to modify the value of this system variable**. | +| [`tidb_idle_transaction_timeout`](/system-variables.md#tidb_idle_transaction_timeout-new-in-v760) | Newly added | Controls the idle timeout for transactions in a user session. When a user session is in a transactional state and remains idle for a duration exceeding the value of this variable, TiDB will terminate the session. The default value `0` means unlimited. | +| [`tidb_opt_enable_fuzzy_binding`](/system-variables.md#tidb_opt_enable_fuzzy_binding-new-in-v760) | Newly added | Controls whether to enable the cross-database binding feature. The default value `OFF` means cross-database binding is disabled. | +| [`tidb_txn_entry_size_limit`](/system-variables.md#tidb_txn_entry_size_limit-new-in-v760) | Newly added | Dynamically modifies the TiDB configuration item [`performance.txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500). It limits the size of a single row of data in TiDB. The default value of this variable is `0`, which means that TiDB uses the value of the configuration item `txn-entry-size-limit` by default. When this variable is set to a non-zero value, `txn-entry-size-limit` is also set to the same value. | +| [`pd_enable_follower_handle_region`](/system-variables.md#pd_enable_follower_handle_region-new-in-v760) | Newly added | Controls whether to enable the [Active PD Follower](/tune-region-performance.md#use-the-active-pd-follower-feature-to-enhance-the-scalability-of-pds-region-information-query-service) feature (experimental). When the value is `OFF`, TiDB only obtains Region information from the PD leader. When the value is `ON`, TiDB evenly distributes requests for Region information to all PD servers, and PD followers can also handle Region requests, thereby reducing the CPU pressure on the PD leader. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`tls-version`](/tidb-configuration-file.md#tls-version) | Modified | The default value is "". The default supported TLS versions of TiDB are changed from `TLS1.1` or higher to `TLS1.2` or higher. | +| TiKV | [`blob-file-compression`](/tikv-configuration-file.md#blob-file-compression) | Modified | The algorithm used for compressing values in Titan, which takes value as the unit. Starting from TiDB v7.6.0, the default compression algorithm is `zstd`. | +| TiKV | [`rocksdb.defaultcf.titan.min-blob-size`](/tikv-configuration-file.md#min-blob-size) | Modified | Starting from TiDB v7.6.0, the default value for new clusters is `32KB`. For existing clusters upgrading to v7.6.0, the default value `1KB` remains unchanged. | +| TiKV | [`rocksdb.titan.enabled`](/tikv-configuration-file.md#enabled) | Modified | Enables or disables Titan. For v7.5.0 and earlier versions, the default value is `false`. Starting from v7.6.0, the default value is `true` for only new clusters. Existing clusters upgraded to v7.6.0 or later versions will retain the original configuration. | +| TiKV | [`gc.num-threads`](/tikv-configuration-file.md#num-threads-new-in-v658-v714-v751-and-v760) | Newly added | When `enable-compaction-filter` is set to `false`, this parameter controls the number of GC threads. The default value is `1`. | +| TiKV | [`raftstore.periodic-full-compact-start-times`](/tikv-configuration-file.md#periodic-full-compact-start-times-new-in-v760) | Newly added | Sets the specific times that TiKV initiates periodic full compaction. The default value `[]` means periodic full compaction is disabled. | +| TiKV | [`raftstore.periodic-full-compact-start-max-cpu`](/tikv-configuration-file.md#periodic-full-compact-start-max-cpu-new-in-v760) | Newly added | Limits the maximum CPU usage rate for TiKV periodic full compaction. The default value is `0.1`. | +| TiKV | [`zstd-dict-size`](/tikv-configuration-file.md#zstd-dict-size) | Newly added | Specifies the `zstd` dictionary compression size. The default value is `"0KB"`, which means to disable the `zstd` dictionary compression. | +| TiFlash | [`logger.level`](/tiflash/tiflash-configuration.md#configure-the-tiflashtoml-file) | Modified | Changes the default value from `"debug"` to `"INFO"` to reduce the cost of logging. | +| TiDB Lightning| [`tidb.pd-addr`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Modified | Configures the addresses of the PD Servers. Starting from v7.6.0, TiDB supports setting multiple PD addresses. | +| TiDB Lightning | [`block-size`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Newly added | Controls the I/O block size for sorting local files in Physical Import Mode (`backend='local'`). The default value is `16KiB`. When the disk IOPS is a bottleneck, you can increase this value to improve performance. | +| BR | [`--granularity`](/br/br-snapshot-guide.md#performance-and-impact-of-snapshot-restore) | Newly added | Uses the coarse-grained Region scatter algorithm (experimental) by specifying `--granularity="coarse-grained"`. This accelerates restore speed in large-scale Region scenarios. | +| TiCDC | [`compression`](/ticdc/ticdc-changefeed-config.md) | Newly added | Controls the behavior to compress redo log files. | +| TiCDC | [`sink.cloud-storage-config`](/ticdc/ticdc-changefeed-config.md) | Newly added | Sets the automatic cleanup of historical data when replicating data to object storage. | + +### System tables + +- Add a new system table [`INFORMATION_SCHEMA.KEYWORDS`](/information-schema/information-schema-keywords.md) to display the information of all keywords supported by TiDB. +- In the system table [`INFORMATION_SCHEMA.SLOW_QUERY`](/information-schema/information-schema-slow-query.md), add the following fields related to Resource Control: + - `Resource_group`: the resource group that the statement is bound to. + - `Request_unit_read`: the total read RUs consumed by the statement. + - `Request_unit_write`: the total write RUs consumed by the statement. + - `Time_queued_by_rc`: the total time that the statement waits for available resources. + +## Offline package changes + +Starting from v7.6.0, the `TiDB-community-server` [binary-package](/binary-package.md) now includes `tiproxy-{version}-linux-{arch}.tar.gz`, which is the installation package for the proxy component [TiProxy](/tiproxy/tiproxy-overview.md). + +## Deprecated features + +* Support for the TLSv1.0 and TLSv1.1 protocols is deprecated in TiDB v7.6.0 and will be removed in v8.0.0. Please upgrade to TLSv1.2 or TLSv1.3. +* The [baseline evolution](/sql-plan-management.md#baseline-evolution) feature for execution plans will be deprecated in TiDB v8.0.0. The equivalent functionality will be redesigned in the subsequent versions. +* The [`tidb_disable_txn_auto_retry`](/system-variables.md#tidb_disable_txn_auto_retry) system variable will be deprecated in TiDB v8.0.0. After that, TiDB will no longer support automatic retries of optimistic transactions. + +## Improvements + ++ TiDB + + - When a non-binary collation is set and the query includes `LIKE`, the optimizer generates an `IndexRangeScan` to improve the execution efficiency [#48181](https://github.com/pingcap/tidb/issues/48181) [#49138](https://github.com/pingcap/tidb/issues/49138) @[time-and-fate](https://github.com/time-and-fate) + - Enhance the ability to convert `OUTER JOIN` to `INNER JOIN` in specific scenarios [#49616](https://github.com/pingcap/tidb/issues/49616) @[qw4990](https://github.com/qw4990) + - Improve the balance of Distributed eXecution Framework (DXF) tasks in the scenario where nodes are restarted [#47298](https://github.com/pingcap/tidb/issues/47298) @[ywqzzy](https://github.com/ywqzzy) + - Support multiple accelerated `ADD INDEX` DDL tasks to be queued for execution, instead of falling back to normal `ADD INDEX` tasks [#47758](https://github.com/pingcap/tidb/issues/47758) @[tangenta](https://github.com/tangenta) + - Improve the compatibility of `ALTER TABLE ... ROW_FORMAT` [#48754](https://github.com/pingcap/tidb/issues/48754) @[hawkingrei](https://github.com/hawkingrei) + - Modify the `CANCEL IMPORT JOB` statement to a synchronous statement [#48736](https://github.com/pingcap/tidb/issues/48736) @[D3Hunter](https://github.com/D3Hunter) + - Improve the speed of adding indexes to empty tables [#49682](https://github.com/pingcap/tidb/issues/49682) @[zimulala](https://github.com/zimulala) + - When the columns of a correlated subquery are not referenced by the upper-level operator, the correlated subquery can be eliminated directly [#45822](https://github.com/pingcap/tidb/issues/45822) @[King-Dylan](https://github.com/King-Dylan) + - `EXCHANGE PARTITION` operations now trigger maintenance updates of statistics [#47354](https://github.com/pingcap/tidb/issues/47354) @[hi-rustin](https://github.com/Rustin170506) + - TiDB supports building binary files that meet the requirements of Federal Information Processing Standards (FIPS) [#47948](https://github.com/pingcap/tidb/issues/47948) @[tiancaiamao](https://github.com/tiancaiamao) + - Optimize the TiDB implementation when handling some type conversions and fix related issues [#47945](https://github.com/pingcap/tidb/issues/47945) [#47864](https://github.com/pingcap/tidb/issues/47864) [#47829](https://github.com/pingcap/tidb/issues/47829) [#47816](https://github.com/pingcap/tidb/issues/47816) @[YangKeao](https://github.com/YangKeao) @[lcwangchao](https://github.com/lcwangchao) + - When obtaining the schema version, TiDB uses the KV timeout feature to read by default, reducing the impact of slow meta Region leader reads on schema version updates [#48125](https://github.com/pingcap/tidb/pull/48125) @[cfzjywxk](https://github.com/cfzjywxk) + ++ TiKV + + - Add an API endpoint `/async_tasks` for querying asynchronous tasks [#15759](https://github.com/tikv/tikv/issues/15759) @[YuJuncen](https://github.com/YuJuncen) + - Add priority labels to gRPC monitoring to display resource group data of different priorities [#49318](https://github.com/pingcap/tidb/issues/49318) @[bufferflies](https://github.com/bufferflies) + - Support dynamically adjusting the value of `readpool.unified.max-tasks-per-worker`, which can calculate the number of running tasks separately based on priority [#16026](https://github.com/tikv/tikv/issues/16026) @[glorv](https://github.com/glorv) + - Support dynamically adjusting the number of GC threads, with a default value of `1` [#16101](https://github.com/tikv/tikv/issues/16101) @[tonyxuqqi](https://github.com/tonyxuqqi) + ++ PD + + - Improve the availability of PD TSO during disk jitter [#7377](https://github.com/tikv/pd/issues/7377) @[HuSharp](https://github.com/HuSharp) + ++ TiFlash + + - Reduce the impact of disk performance jitter on read latency [#8583](https://github.com/pingcap/tiflash/issues/8583) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Reduce the impact of background GC tasks on read and write task latency [#8650](https://github.com/pingcap/tiflash/issues/8650) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Support merging identical data reading operations in a storage-compute separation architecture to improve data scanning performance under high concurrency [#6834](https://github.com/pingcap/tiflash/issues/6834) @[JinheLin](https://github.com/JinheLin) + - Optimize the execution performance of `SEMI JOIN` and `LEFT OUTER SEMIJOIN` when only JOIN KEY equality conditions are included in `JOIN ON` [#47424](https://github.com/pingcap/tidb/issues/47424) @[gengliqi](https://github.com/gengliqi) + ++ Tools + + + Backup & Restore (BR) + + - Support authentication using Amazon S3 `session-token` and `assume-role` during full backup recovery phase [#39832](https://github.com/pingcap/tidb/issues/39832) @[3pointer](https://github.com/3pointer) + - Introduce a new integration test for Point-In-Time Recovery (PITR) in the `delete range` scenario, enhancing PITR stability [#47738](https://github.com/pingcap/tidb/issues/47738) @[Leavrth](https://github.com/Leavrth) + - Improve the table creation performance of the `RESTORE` statement in scenarios with large datasets [#48301](https://github.com/pingcap/tidb/issues/48301) @[Leavrth](https://github.com/Leavrth) + - Refactor the BR exception handling mechanism to increase tolerance for unknown errors [#47656](https://github.com/pingcap/tidb/issues/47656) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Improve the performance of TiCDC replicating data to object storage by increasing parallelism [#10098](https://github.com/pingcap/tiflow/issues/10098) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Support making TiCDC Canal-JSON content format [compatible with the content format of the official Canal output](/ticdc/ticdc-canal-json.md#compatibility-with-the-official-canal) by setting `content-compatible=true` in the `sink-uri` configuration [#10106](https://github.com/pingcap/tiflow/issues/10106) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - Add configurations for full data physical import to DM OpenAPI [#10193](https://github.com/pingcap/tiflow/issues/10193) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Support configuring multiple PD addresses to enhance stability [#49515](https://github.com/pingcap/tidb/issues/49515) @[mittalrishabh](https://github.com/mittalrishabh) + - Support configuring the `block-size` parameter to control the I/O block size for sorting local files to improve performance [#45037](https://github.com/pingcap/tidb/issues/45037) @[mittalrishabh](https://github.com/mittalrishabh) + +## Bug fixes + ++ TiDB + + - Fix the issue that TiDB panics and reports an error `invalid memory address or nil pointer dereference` [#42739](https://github.com/pingcap/tidb/issues/42739) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Fix the TiDB node panic issue that occurs when DDL `jobID` is restored to 0 [#46296](https://github.com/pingcap/tidb/issues/46296) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the same query plan has different `PLAN_DIGEST` values in some cases [#47634](https://github.com/pingcap/tidb/issues/47634) @[King-Dylan](https://github.com/King-Dylan) + - Fix the issue that executing `UNION ALL` with the DUAL table as the first subnode might cause an error [#48755](https://github.com/pingcap/tidb/issues/48755) @[winoros](https://github.com/winoros) + - Fix the issue that queries containing common table expressions (CTEs) report `runtime error: index out of range [32] with length 32` when `tidb_max_chunk_size` is set to a small value [#48808](https://github.com/pingcap/tidb/issues/48808) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue of Goroutine leak when using `AUTO_ID_CACHE=1` [#46324](https://github.com/pingcap/tidb/issues/46324) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the result of `COUNT(INT)` calculated by MPP might be incorrect [#48643](https://github.com/pingcap/tidb/issues/48643) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that executing `ALTER TABLE ... LAST PARTITION` fails when the partition column type is `DATETIME` [#48814](https://github.com/pingcap/tidb/issues/48814) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that using the `_` wildcard in `LIKE` when the data contains trailing spaces can result in incorrect query results [#48983](https://github.com/pingcap/tidb/issues/48983) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that high CPU usage of TiDB occurs due to long-term memory pressure caused by `tidb_server_memory_limit` [#48741](https://github.com/pingcap/tidb/issues/48741) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that the query result is incorrect when an `ENUM` type column is used as the join key [#48991](https://github.com/pingcap/tidb/issues/48991) @[winoros](https://github.com/winoros) + - Fix the issue that queries containing CTEs unexpectedly get stuck when the memory limit is exceeded [#49096](https://github.com/pingcap/tidb/issues/49096) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that TiDB server might consume a significant amount of resources when the enterprise plugin for audit logging is used [#49273](https://github.com/pingcap/tidb/issues/49273) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the optimizer incorrectly converts TiFlash selection path to the DUAL table in specific scenarios [#49285](https://github.com/pingcap/tidb/issues/49285) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `UPDATE` or `DELETE` statements containing `WITH RECURSIVE` CTEs might produce incorrect results [#48969](https://github.com/pingcap/tidb/issues/48969) @[winoros](https://github.com/winoros) + - Fix the issue that a query containing the IndexHashJoin operator gets stuck when memory exceeds `tidb_mem_quota_query` [#49033](https://github.com/pingcap/tidb/issues/49033) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that in non-strict mode (`sql_mode = ''`), truncation during executing `INSERT` still reports an error [#49369](https://github.com/pingcap/tidb/issues/49369) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that CTE queries might report an error `type assertion for CTEStorageMap failed` during the retry process [#46522](https://github.com/pingcap/tidb/issues/46522) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that `LIMIT` and `ORDER BY` might be invalid in nested `UNION` queries [#49377](https://github.com/pingcap/tidb/issues/49377) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that parsing invalid values of `ENUM` or `SET` types would directly cause SQL statement errors [#49487](https://github.com/pingcap/tidb/issues/49487) @[winoros](https://github.com/winoros) + - Fix the issue of excessive statistical error in constructing statistics caused by Golang's implicit conversion algorithm [#49801](https://github.com/pingcap/tidb/issues/49801) @[qw4990](https://github.com/qw4990) + - Fix the issue that Daylight Saving Time is displayed incorrectly in some time zones [#49586](https://github.com/pingcap/tidb/issues/49586) @[overvenus](https://github.com/overvenus) + - Fix the issue that tables with `AUTO_ID_CACHE=1` might lead to gRPC client leaks when there are a large number of tables [#48869](https://github.com/pingcap/tidb/issues/48869) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that TiDB server might panic during graceful shutdown [#36793](https://github.com/pingcap/tidb/issues/36793) @[bb7133](https://github.com/bb7133) + - Fix the issue that `ADMIN RECOVER INDEX` reports `ERROR 1105` when processing a table containing `CommonHandle` [#47687](https://github.com/pingcap/tidb/issues/47687) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that specifying placement rules when executing `ALTER TABLE t PARTITION BY` reports the error `ERROR 8239` [#48630](https://github.com/pingcap/tidb/issues/48630) @[mjonss](https://github.com/mjonss) + - Fix the issue that the `START_TIME` column type in `INFORMATION_SCHEMA.CLUSTER_INFO` is not valid [#45221](https://github.com/pingcap/tidb/issues/45221) @[dveeden](https://github.com/dveeden) + - Fix the issue that invalid `EXTRA` column type in `INFORMATION_SCHEMA.COLUMNS` leads to the error `Data Too Long, field len 30, data len 45` [#42030](https://github.com/pingcap/tidb/issues/42030) @[tangenta](https://github.com/tangenta) + - Fix the issue that `IN (...)` causes different plan digests in `INFORMATION_SCHEMA.STATEMENTS_SUMMARY` [#33559](https://github.com/pingcap/tidb/issues/33559) @[King-Dylan](https://github.com/King-Dylan) + - Fix the issue that when converting the `TIME` type to the `YEAR` type, the returned result mixes `TIME` and the year [#48557](https://github.com/pingcap/tidb/issues/48557) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that disabling `tidb_enable_collect_execution_info` causes the coprocessor cache to panic [#48212](https://github.com/pingcap/tidb/issues/48212) @[you06](https://github.com/you06) + - Fix the issue that TiDB crashes when `shuffleExec` quits unexpectedly [#48230](https://github.com/pingcap/tidb/issues/48230) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that static `CALIBRATE RESOURCE` relies on the Prometheus data [#49174](https://github.com/pingcap/tidb/issues/49174) @[glorv](https://github.com/glorv) + - Fix the issue that when adding a large interval to a date, it returns an incorrect result. After the fix, an interval with an invalid prefix or the string `true` is treated as zero, which is consistent with MySQL 8.0 [#49227](https://github.com/pingcap/tidb/issues/49227) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the `ROW` function incorrectly infers the `null` type and causes an unexpected error [#49015](https://github.com/pingcap/tidb/issues/49015) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the `ILIKE` function might cause data race in some scenarios [#49677](https://github.com/pingcap/tidb/issues/49677) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that query results are incorrect due to `STREAM_AGG()` incorrectly handling CI [#49902](https://github.com/pingcap/tidb/issues/49902) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that encoding fails when converting bytes to `TIME` [#47346](https://github.com/pingcap/tidb/issues/47346) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the behavior of the `ENFORCED` option in the `CHECK` constraint is inconsistent with MySQL 8.0 [#47567](https://github.com/pingcap/tidb/issues/47567) [#47631](https://github.com/pingcap/tidb/issues/47631) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that DDL statements with the `CHECK` constraint are stuck [#47632](https://github.com/pingcap/tidb/issues/47632) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that adding index fails for DDL statements due to out of memory [#47862](https://github.com/pingcap/tidb/issues/47862) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the issue that upgrading the cluster during executing `ADD INDEX` might cause the data to be inconsistent with the indexes [#46306](https://github.com/pingcap/tidb/issues/46306) @[zimulala](https://github.com/zimulala) + - Fix the issue that executing `ADMIN CHECK` after updating the `tidb_mem_quota_query` system variable returns `ERROR 8175` [#49258](https://github.com/pingcap/tidb/issues/49258) @[tangenta](https://github.com/tangenta) + - Fix the issue that when `ALTER TABLE` modifies the type of a column referenced by a foreign key, the change in `DECIMAL` precision is not reported as an error [#49836](https://github.com/pingcap/tidb/issues/49836) @[yoshikipom](https://github.com/yoshikipom) + - Fix the issue that when `ALTER TABLE` modifies the type of a column referenced by a foreign key, the change in `INTEGER` length is reported as an error by mistake [#47702](https://github.com/pingcap/tidb/issues/47702) @[yoshikipom](https://github.com/yoshikipom) + - Fix the issue that in some scenarios the expression index does not detect that the divisor is 0 [#50053](https://github.com/pingcap/tidb/issues/50053) @[lcwangchao](https://github.com/lcwangchao) + - Mitigate the issue that TiDB nodes might encounter OOM errors when dealing with a large number of tables [#50077](https://github.com/pingcap/tidb/issues/50077) @[zimulala](https://github.com/zimulala) + - Fix the issue that DDL gets stuck in the running state during cluster rolling restart [#50073](https://github.com/pingcap/tidb/issues/50073) @[tangenta](https://github.com/tangenta) + - Fix the issue that results might be incorrect when accessing global indexes of partitioned tables using `PointGet` or `BatchPointGet` operators [#47539](https://github.com/pingcap/tidb/issues/47539) @[L-maple](https://github.com/L-maple) + - Fix the issue that MPP plans might not be selected when indexes on generated columns are set as visible [#47766](https://github.com/pingcap/tidb/issues/47766) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `LIMIT` might not be pushed down to the `OR` type `Index Merge` [#48588](https://github.com/pingcap/tidb/issues/48588) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that duplicate built-in rows might exist in the `mysql.bind_info` table after BR import [#46527](https://github.com/pingcap/tidb/issues/46527) @[qw4990](https://github.com/qw4990) + - Fix the issue that statistics for partitioned tables are not updated as expected after partitions are dropped [#48182](https://github.com/pingcap/tidb/issues/48182) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that errors might be returned during the concurrent merging of global statistics for partitioned tables [#48713](https://github.com/pingcap/tidb/issues/48713) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that query results might be incorrect when the `LIKE` operator is used for index range scans on a column with PADDING SPACE [#48821](https://github.com/pingcap/tidb/issues/48821) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that generated columns might trigger concurrent read and write on memory and result in data race [#44919](https://github.com/pingcap/tidb/issues/44919) @[tangenta](https://github.com/tangenta) + - Fix the issue that `ANALYZE TABLE` might still collect Top1 statistics even when `WITH 0 TOPN` (indicating not collecting topN statistics) is specified [#49080](https://github.com/pingcap/tidb/issues/49080) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that illegal optimizer hints might cause valid hints to be ineffective [#49308](https://github.com/pingcap/tidb/issues/49308) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that statistics for Hash partitioned tables are not correspondingly updated when you add, drop, reorganize, or `TRUNCATE` partitions [#48235](https://github.com/pingcap/tidb/issues/48235) [#48233](https://github.com/pingcap/tidb/issues/48233) [#48226](https://github.com/pingcap/tidb/issues/48226) [#48231](https://github.com/pingcap/tidb/issues/48231) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that after the time window for automatic statistics updates is configured, statistics might still be updated outside that time window [#49552](https://github.com/pingcap/tidb/issues/49552) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that old statistics are not automatically deleted when a partitioned table is converted to a non-partitioned table [#49547](https://github.com/pingcap/tidb/issues/49547) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that old statistics are not automatically deleted when you clear data from a non-partitioned table using `TRUNCATE TABLE` [#49663](https://github.com/pingcap/tidb/issues/49663) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that enforced sorting might become ineffective when a query uses optimizer hints (such as `STREAM_AGG()`) that enforce sorting and its execution plan contains `IndexMerge` [#49605](https://github.com/pingcap/tidb/issues/49605) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that histogram statistics might not be parsed into readable strings when the histogram boundary contains `NULL` [#49823](https://github.com/pingcap/tidb/issues/49823) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that executing queries containing the `GROUP_CONCAT(ORDER BY)` syntax might return errors [#49986](https://github.com/pingcap/tidb/issues/49986) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `UPDATE`, `DELETE`, and `INSERT` statements return overflow errors instead of warnings when the `SQL_MODE` is not strict [#49137](https://github.com/pingcap/tidb/issues/49137) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that data cannot be inserted when a table has a composite index consisting of multi-valued indexes and non-binary type strings [#49680](https://github.com/pingcap/tidb/issues/49680) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `LIMIT` in multi-level nested `UNION` queries might become ineffective [#49874](https://github.com/pingcap/tidb/issues/49874) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that querying partitioned tables with the `BETWEEN ... AND ...` condition returns incorrect results [#49842](https://github.com/pingcap/tidb/issues/49842) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that hints cannot be used in `REPLACE INTO` statements [#34325](https://github.com/pingcap/tidb/issues/34325) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that TiDB might select the wrong partition when querying Hash partitioned tables [#50044](https://github.com/pingcap/tidb/issues/50044) @[Defined2014](https://github.com/Defined2014) + - Fix the connection error that occurs when you use MariaDB Connector/J with compression enabled [#49845](https://github.com/pingcap/tidb/issues/49845) @[onlyacat](https://github.com/onlyacat) + ++ TiKV + + - Fix the issue that the damaged SST files might spread to other TiKV nodes and cause TiKV to panic [#15986](https://github.com/tikv/tikv/issues/15986) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that Online Unsafe Recovery cannot handle merge abort [#15580](https://github.com/tikv/tikv/issues/15580) @[v01dstar](https://github.com/v01dstar) + - Fix the issue that the joint state of DR Auto-Sync might time out when scaling out [#15817](https://github.com/tikv/tikv/issues/15817) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that `blob-run-mode` in Titan cannot be updated online [#15978](https://github.com/tikv/tikv/issues/15978) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that Resolved TS might be blocked for two hours [#11847](https://github.com/tikv/tikv/issues/11847) [#15520](https://github.com/tikv/tikv/issues/15520) [#39130](https://github.com/pingcap/tidb/issues/39130) @[overvenus](https://github.com/overvenus) + - Fix the issue that Flashback might get stuck when encountering `notLeader` or `regionNotFound` [#15712](https://github.com/tikv/tikv/issues/15712) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that if TiKV runs extremely slowly, it might panic after Region merge [#16111](https://github.com/tikv/tikv/issues/16111) @[overvenus](https://github.com/overvenus) + - Fix the issue that TiKV cannot read in-memory pessimistic locks when GC scans expired locks [#15066](https://github.com/tikv/tikv/issues/15066) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that the blob file size in Titan monitoring is incorrect [#15971](https://github.com/tikv/tikv/issues/15971) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that replicating large tables using TiCDC might cause TiKV to OOM [#16035](https://github.com/tikv/tikv/issues/16035) @[overvenus](https://github.com/overvenus) + - Fix the issue that TiDB and TiKV might produce inconsistent results when processing `DECIMAL` arithmetic multiplication truncation [#16268](https://github.com/tikv/tikv/issues/16268) @[solotzg](https://github.com/solotzg) + - Fix the issue that `cast_duration_as_time` might return incorrect results [#16211](https://github.com/tikv/tikv/issues/16211) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that TiKV converts the time zone incorrectly for Brazil and Egypt [#16220](https://github.com/tikv/tikv/issues/16220) @[overvenus](https://github.com/overvenus) + - Fix the issue that TiKV might panic when gRPC threads are checking `is_shutdown` [#16236](https://github.com/tikv/tikv/issues/16236) @[pingyu](https://github.com/pingyu) + ++ PD + + - Fix the issue that the etcd health check in PD does not remove expired addresses [#7226](https://github.com/tikv/pd/issues/7226) @[iosmanthus](https://github.com/iosmanthus) + - Fix the issue that when PD leader is transferred and there is a network partition between the new leader and the PD client, the PD client fails to update the information of the leader [#7416](https://github.com/tikv/pd/issues/7416) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix some security issues by upgrading the version of Gin Web Framework from v1.8.1 to v1.9.1 [#7438](https://github.com/tikv/pd/issues/7438) @[niubell](https://github.com/niubell) + - Fix the issue that the orphan peer is deleted when the number of replicas does not meet the requirements [#7584](https://github.com/tikv/pd/issues/7584) @[bufferflies](https://github.com/bufferflies) + ++ TiFlash + + - Fix the issue of memory leak when TiFlash encounters memory limitation during query [#8447](https://github.com/pingcap/tiflash/issues/8447) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that data of TiFlash replicas would still be garbage collected after executing `FLASHBACK DATABASE` [#8450](https://github.com/pingcap/tiflash/issues/8450) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that the memory usage increases significantly due to slow queries [#8564](https://github.com/pingcap/tiflash/issues/8564) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that some TiFlash replica data cannot be recovered through `RECOVER TABLE` or `FLASHBACK TABLE` in scenarios with frequent execution of `CREATE TABLE` and `DROP TABLE` [#1664](https://github.com/pingcap/tiflash/issues/1664) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that query results are incorrect when querying with filtering conditions like `ColumnRef in (Literal, Func...)` [#8631](https://github.com/pingcap/tiflash/issues/8631) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the TiFlash panic issue when TiFlash encounters conflicts during concurrent DDL execution [#8578](https://github.com/pingcap/tiflash/issues/8578) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might not be able to select the GC owner of object storage data under the disaggregated storage and compute architecture [#8519](https://github.com/pingcap/tiflash/issues/8519) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that the `lowerUTF8` and `upperUTF8` functions do not allow characters in different cases to occupy different bytes [#8484](https://github.com/pingcap/tiflash/issues/8484) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that TiFlash incorrectly handles `ENUM` when the `ENUM` value is 0 [#8311](https://github.com/pingcap/tiflash/issues/8311) @[solotzg](https://github.com/solotzg) + - Fix the incompatibility issue in the `INET_NTOA()` expression [#8211](https://github.com/pingcap/tiflash/issues/8211) @[solotzg](https://github.com/solotzg) + - Fix the potential OOM issue that might occur when scanning multiple partitioned tables during stream read [#8505](https://github.com/pingcap/tiflash/issues/8505) @[gengliqi](https://github.com/gengliqi) + - Fix the issue that short queries executed successfully print excessive info logs [#8592](https://github.com/pingcap/tiflash/issues/8592) @[windtalker](https://github.com/windtalker) + - Fix the issue that TiFlash might crash when it is stopped [#8550](https://github.com/pingcap/tiflash/issues/8550) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the random invalid memory access issue that might occur with `GREATEST` or `LEAST` functions containing constant string parameters [#8604](https://github.com/pingcap/tiflash/issues/8604) @[windtalker](https://github.com/windtalker) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that BR generates incorrect URIs for external storage files [#48452](https://github.com/pingcap/tidb/issues/48452) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the log backup task can start but does not work properly if failing to connect to PD during task initialization [#16056](https://github.com/tikv/tikv/issues/16056) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the log backup task might encounter memory leak and fail to run properly after startup [#16070](https://github.com/tikv/tikv/issues/16070) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that inserting data into the system table `mysql.gc_delete_range` during the PITR process returns an error [#49346](https://github.com/pingcap/tidb/issues/49346) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the `Unsupported collation` error is reported when you restore data from backups of an old version [#49466](https://github.com/pingcap/tidb/issues/49466) @[3pointer](https://github.com/3pointer) + - Fix the issue that permissions are not updated timely after user tables are recovered through snapshots in certain scenarios [#49394](https://github.com/pingcap/tidb/issues/49394) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Fix the issue that the `WHERE` clause does not use the primary key as a condition when replicating `DELETE` statements in certain scenarios [#9812](https://github.com/pingcap/tiflow/issues/9812) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the TiCDC server might panic when replicating data to an object storage service [#10137](https://github.com/pingcap/tiflow/issues/10137) @[sdojjy](https://github.com/sdojjy) + - Fix the potential data race issue during `kv-client` initialization [#10095](https://github.com/pingcap/tiflow/issues/10095) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that TiCDC mistakenly closes the connection with TiKV in certain special scenarios [#10239](https://github.com/pingcap/tiflow/issues/10239) @[hicqu](https://github.com/hicqu) + - Fix the issue that TiCDC server might panic when executing lossy DDL statements in upstream [#9739](https://github.com/pingcap/tiflow/issues/9739) @[hicqu](https://github.com/hicqu) + - Fix the issue that `checkpoint-ts` might get stuck when TiCDC replicates data to downstream MySQL [#10334](https://github.com/pingcap/tiflow/issues/10334) @[zhangjinpeng87](https://github.com/zhangjinpeng87) + + + TiDB Data Migration (DM) + + - Fix the issue that DM encounters "event type truncate not valid" error that causes the upgrade to fail [#10282](https://github.com/pingcap/tiflow/issues/10282) @[GMHDBJD](https://github.com/GMHDBJD) + - Fix the performance degradation issue when replicating data in GTID mode [#9676](https://github.com/pingcap/tiflow/issues/9676) @[feran-morgan-pingcap](https://github.com/feran-morgan-pingcap) + - Fix the issue that a migration task error occurs when the downstream table structure contains `shard_row_id_bits` [#10308](https://github.com/pingcap/tiflow/issues/10308) @[GMHDBJD](https://github.com/GMHDBJD) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [0o001](https://github.com/0o001) (First-time contributor) +- [bagechengzi](https://github.com/bagechengzi) (First-time contributor) +- [feran-morgan-pingcap](https://github.com/feran-morgan-pingcap) (First-time contributor) +- [highpon](https://github.com/highpon) +- [jiyfhust](https://github.com/jiyfhust) +- [L-maple](https://github.com/L-maple) +- [lkshminarayanan](https://github.com/lkshminarayanan) (First-time contributor) +- [lyang24](https://github.com/lyang24) (First-time contributor) +- [mittalrishabh](https://github.com/mittalrishabh) +- [morgo](https://github.com/morgo) +- [nkg-](https://github.com/nkg-) (First-time contributor) +- [onlyacat](https://github.com/onlyacat) +- [shawn0915](https://github.com/shawn0915) +- [Smityz](https://github.com/Smityz) +- [szpnygo](https://github.com/szpnygo) (First-time contributor) +- [ub-3](https://github.com/ub-3) (First-time contributor) +- [xiaoyawei](https://github.com/xiaoyawei) (First-time contributor) +- [yorkhellen](https://github.com/yorkhellen) +- [yoshikipom](https://github.com/yoshikipom) (First-time contributor) +- [Zheaoli](https://github.com/Zheaoli) diff --git a/releases/release-8.0.0.md b/releases/release-8.0.0.md new file mode 100644 index 0000000000000..c3abf2af61c31 --- /dev/null +++ b/releases/release-8.0.0.md @@ -0,0 +1,601 @@ +--- +title: TiDB 8.0.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 8.0.0. +--- + +# TiDB 8.0.0 Release Notes + +Release date: March 29, 2024 + +TiDB version: 8.0.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v8.0/quick-start-with-tidb) + +8.0.0 introduces the following key features and improvements: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeature/EnhancementDescription
Scalability and PerformanceDisaggregation of PD to improve scalability (experimental) Placement Driver (PD) contains multiple critical modules to ensure the normal operation of TiDB clusters. As the workload of a cluster increases, the resource consumption of each module in PD also increases, causing mutual interference between these modules and ultimately affecting the overall service quality of the cluster. Starting from v8.0.0, TiDB addresses this issue by splitting the TSO and scheduling modules in PD into independently deployable microservices. This can significantly reduce the mutual interference between modules as the cluster scales. With this architecture, much larger clusters with much larger workloads are now possible.
Bulk DML for much larger transactions (experimental)Large batch DML jobs, such as extensive cleanup jobs, joins, or aggregations, can consume a significant amount of memory and have previously been limited at very large scales. Bulk DML (tidb_dml_type = "bulk") is a new DML type for handling large batch DML tasks more efficiently while providing transaction guarantees and mitigating OOM issues. This feature differs from import, load, and restore operations when used for data loading.
Acceleration of cluster snapshot restore speed (GA) With this feature, BR can fully leverage the scale advantage of a cluster, enabling all TiKV nodes in the cluster to participate in the preparation step of data restores. This feature can significantly improve the restore speed of large datasets in large-scale clusters. Real-world tests show that this feature can saturate the download bandwidth, with the download speed improving by 8 to 10 times, and the end-to-end restore speed improving by approximately 1.5 to 3 times.
Enhance the stability of caching the schema information when there is a massive number of tables (experimental)SaaS companies using TiDB as the system of record for their multi-tenant applications often need to store a substantial number of tables. In previous versions, handling table counts in the order of a million or more was feasible, but it had the potential to degrade the overall user experience. TiDB v8.0.0 improves the situation by implementing a priority queue for auto analyze, making the process less rigid and enhancing stability across a wider array of tables.
DB Operations and ObservabilitySupport monitoring index usage statistics Proper index design is a crucial prerequisite to maintaining database performance. TiDB v8.0.0 introduces the INFORMATION_SCHEMA.TIDB_INDEX_USAGE table and the sys.schema_unused_indexes view to provide usage statistics of indexes. This feature helps you assess the efficiency of indexes in the database and optimize the index design.
Data MigrationTiCDC adds support for the Simple protocol TiCDC introduces a new protocol, the Simple protocol. This protocol provides in-band schema tracking capabilities by embedding table schema information in DDL and BOOTSTRAP events.
TiCDC adds support for the Debezium format protocol TiCDC introduces a new protocol, the Debezium protocol. TiCDC can now publish data change events to a Kafka sink using a protocol that generates Debezium style messages.
+ +## Feature details + +### Scalability + +- PD supports the microservice mode (experimental) [#5766](https://github.com/tikv/pd/issues/5766) @[binshi-bing](https://github.com/binshi-bing) + + Starting from v8.0.0, PD supports the microservice mode. This mode splits the timestamp allocation and cluster scheduling functions of PD into separate microservices that can be deployed independently, thereby enhancing performance scalability for PD and addressing performance bottlenecks of PD in large-scale clusters. + + - `tso` microservice: provides monotonically increasing timestamp allocation for the entire cluster. + - `scheduling` microservice: provides scheduling functions for the entire cluster, including but not limited to load balancing, hot spot handling, replica repair, and replica placement. + + Each microservice is deployed as an independent process. If you configure more than one replica for a microservice, the microservice automatically implements a primary-secondary fault-tolerant mode to ensure high availability and reliability of the service. + + Currently, PD microservices can only be deployed using TiDB Operator. It is recommended to consider this mode when PD becomes a significant performance bottleneck that cannot be resolved by scaling up. + + For more information, see [documentation](/pd-microservices.md). + +* Enhance the usability of the Titan engine [#16245](https://github.com/tikv/tikv/issues/16245) @[Connor1996](https://github.com/Connor1996) + + - Enable the shared cache for Titan blob files and RocksDB block files by default ([`shared-blob-cache`](/tikv-configuration-file.md#shared-blob-cache-new-in-v800) defaults to `true`), eliminating the need to configure [`blob-cache-size`](/tikv-configuration-file.md#blob-cache-size) separately. + - Support dynamically modifying [`min-blob-size`](/tikv-configuration-file.md#min-blob-size), [`blob-file-compression`](/tikv-configuration-file.md#blob-file-compression), and [`discardable-ratio`](/tikv-configuration-file.md#min-blob-size) to improve performance and flexibility when using the Titan engine. + + For more information, see [documentation](/storage-engine/titan-configuration.md). + +### Performance + +* BR improves snapshot restore speed (GA) [#50701](https://github.com/pingcap/tidb/issues/50701) @[3pointer](https://github.com/3pointer) @[Leavrth](https://github.com/Leavrth) + + Starting from TiDB v8.0.0, the acceleration of snapshot restore speed is now generally available (GA) and enabled by default. BR improves the snapshot restore speed significantly by implementing various optimizations such as adopting the coarse-grained Region scattering algorithm, creating databases and tables in batches, reducing the mutual impact between SST file downloads and ingest operations, and accelerating the restore of table statistics. According to test results from real-world cases, the data restore speed of a single TiKV node stabilizes at 1.2 GiB/s, and 100 TiB of data can be restored within one hour. + + This means that even in high-load environments, BR can fully utilize the resources of each TiKV node, significantly reducing database restore time, enhancing the availability and reliability of databases, and reducing downtime and business losses caused by data loss or system failures. Note that the increase in restore speed is attributed to the parallel execution of a large number of goroutines, which can result in significant memory consumption, especially when there are many tables or Regions. It is recommended to use machines with higher memory capacity to run the BR client. If the memory capacity of the machine is limited, it is recommended to use a finer-grained Region scattering algorithm. In addition, because the coarse-grained Region scattering algorithm might consume a significant amount of external storage bandwidth, you need to avoid any impact on other applications due to insufficient external bandwidth. + + For more information, see [documentation](/br/br-snapshot-guide.md#restore-cluster-snapshots). + +* Support pushing down the following functions to TiFlash [#50975](https://github.com/pingcap/tidb/issues/50975) [#50485](https://github.com/pingcap/tidb/issues/50485) @[yibin87](https://github.com/yibin87) @[windtalker](https://github.com/windtalker) + + * `CAST(DECIMAL AS DOUBLE)` + * `POWER()` + + For more information, see [documentation](/tiflash/tiflash-supported-pushdown-calculations.md). + +* The parallel HashAgg algorithm of TiDB supports disk spill (experimental) [#35637](https://github.com/pingcap/tidb/issues/35637) @[xzhangxian1008](https://github.com/xzhangxian1008) + + In earlier versions of TiDB, the concurrency algorithm of the HashAgg operator does not support disk spill. If the execution plan of a SQL statement contains the parallel HashAgg operator, all the data for that SQL statement can only be processed in memory. Consequently, TiDB has to process a large amount of data in memory. When the data size exceeds the memory limit, TiDB can only choose the non-parallel algorithm, which does not leverage concurrency for performance improvement. + + In v8.0.0, the parallel HashAgg algorithm of TiDB supports disk spill. Under any parallel conditions, the HashAgg operator can automatically trigger data spill based on memory usage, thus balancing performance and data throughput. Currently, as an experimental feature, TiDB introduces the `tidb_enable_parallel_hashagg_spill` variable to control whether to enable the parallel HashAgg algorithm that supports disk spill. When this variable is `ON`, it means enabled. This variable will be deprecated after the feature is generally available in a future release. + + For more information, see [documentation](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800). + +* Introduce the priority queue for automatic statistics collection [#50132](https://github.com/pingcap/tidb/issues/50132) @[hi-rustin](https://github.com/Rustin170506) + + Maintaining optimizer statistics up-to-date is the key to stabilizing database performance. Most users rely on the [automatic statistics collection](/statistics.md#automatic-update) provided by TiDB to collect the latest statistics. Automatic statistics collection checks the status of statistics for all objects, and adds unhealthy objects to a queue for sequential collections. In previous versions, the order is random, which could result in excessive waits for more worthy candidates to be updated, causing potential performance regressions. + + Starting from v8.0.0, automatic statistics collection dynamically sets priorities for objects in combination with a variety of conditions to ensure that more deserving candidates are processed in priority, such as newly created indexes and partitioned tables with definition changes. Additionally, TiDB prioritizes tables with lower health scores, placing them at the top of the queue. This enhancement makes the order of collection more reasonable, and reduces performance problems caused by outdated statistics, therefore improving database stability. + + For more information, see [documentation](/system-variables.md#tidb_enable_auto_analyze_priority_queue-new-in-v800). + +* Remove some limitations on execution plan cache [#49161](https://github.com/pingcap/tidb/pull/49161) @[mjonss](https://github.com/mjonss) @[qw4990](https://github.com/qw4990) + + TiDB supports [plan cache](/sql-prepared-plan-cache.md), which can effectively reduce the latency of OLTP systems and is important for performance. In v8.0.0, TiDB removes several limitations on plan cache. Execution plans with the following items can be cached now: + + - [Partitioned tables](/partitioned-table.md) + - [Generated columns](/generated-columns.md), including objects that depend on generated columns (such as [multi-valued indexes](/choose-index.md#multi-valued-indexes-and-plan-cache)) + + This enhancement extends the use cases of plan cache and improves the overall database performance in complex scenarios. + + For more information, see [documentation](/sql-prepared-plan-cache.md). + +* Optimizer enhances support for multi-valued indexes [#47759](https://github.com/pingcap/tidb/issues/47759) [#46539](https://github.com/pingcap/tidb/issues/46539) @[Arenatlx](https://github.com/Arenatlx) @[time-and-fate](https://github.com/time-and-fate) + + TiDB v6.6.0 introduces [multi-value indexes](/sql-statements/sql-statement-create-index.md#multi-valued-indexes) to improve query performance for JSON data types. In v8.0.0, the optimizer enhances its support for multi-valued indexes and can correctly identify and utilize them to optimize queries in complex scenarios. + + * The optimizer collects statistics on multi-valued indexes and decides execution plans with the statistics. If several multi-value indexes can be selected by a SQL statement, the optimizer can identify the one with lower cost. + * When using `OR` to connect multiple `member of` conditions, the optimizer can match an effective index partial path for each DNF item (a `member of` condition) and combine these paths using Union to form an `Index Merge`. This achieves more efficient condition filtering and data fetch. + + For more information, see [documentation](/sql-statements/sql-statement-create-index.md#multi-valued-indexes). + +* Support configuring the update interval for low-precision TSO [#51081](https://github.com/pingcap/tidb/issues/51081) @[Tema](https://github.com/Tema) + + The [low-precision TSO feature](/system-variables.md#tidb_low_resolution_tso) in TiDB uses regularly updated TSO as the transaction timestamp. In scenarios where reading outdated data is acceptable, this feature reduces the overhead of obtaining TSO for small read-only transactions by sacrificing real-time performance and improves the ability of high-concurrency reads. + + Before v8.0.0, the TSO update interval of low-precision TSO feature is fixed and cannot be adjusted according to actual application requirements. In v8.0.0, TiDB introduces the system variable `tidb_low_resolution_tso_update_interval` to control the TSO update interval. This feature takes effect only when the low-precision TSO feature is enabled. + + For more information, see [documentation](/system-variables.md#tidb_low_resolution_tso_update_interval-new-in-v800). + +### Availability + +* The proxy component TiProxy becomes generally available (GA) [#413](https://github.com/pingcap/tiproxy/issues/413) @[djshow832](https://github.com/djshow832) @[xhebox](https://github.com/xhebox) + + TiDB v7.6.0 introduces the proxy component TiProxy as an experimental feature. TiProxy is the official proxy component of TiDB, located between the client and TiDB server. It provides load balancing and connection persistence functions for TiDB, making the workload of the TiDB cluster more balanced and not affecting user access to the database during maintenance operations. + + In v8.0.0, TiProxy becomes generally available and enhances the automatic generation of signature certificates and monitoring functions. + + The usage scenarios of TiProxy are as follows: + + - During maintenance operations such as rolling restarts, rolling upgrades, and scaling-in in a TiDB cluster, changes occur in the TiDB servers which result in interruptions in connections between clients and the TiDB servers. By using TiProxy, connections can be smoothly migrated to other TiDB servers during these maintenance operations so that clients are not affected. + - Client connections to a TiDB server cannot be dynamically migrated to other TiDB servers. When the workload of multiple TiDB servers is unbalanced, it might result in a situation where the overall cluster resources are sufficient, but certain TiDB servers experience resource exhaustion leading to a significant increase in latency. To address this issue, TiProxy provides dynamic migration for connection, which allows connections to be migrated from one TiDB server to another without any impact on the clients, thereby achieving load balancing for the TiDB cluster. + + TiProxy has been integrated into TiUP, TiDB Operator, and TiDB Dashboard, making it easy to configure, deploy, and maintain. + + For more information, see [documentation](/tiproxy/tiproxy-overview.md). + +### SQL + +* Support a new DML type for handling a large amount of data (experimental) [#50215](https://github.com/pingcap/tidb/issues/50215) @[ekexium](https://github.com/ekexium) + + Before v8.0.0, TiDB stores all transaction data in memory before committing. When processing a large amount of data, the memory required for transactions becomes a bottleneck that limits the transaction size that TiDB can handle. Although TiDB introduces non-transactional DML to attempt to solve the transaction size limitation by splitting SQL statements, this feature has various limitations and does not provide an ideal experience in actual scenarios. + + Starting from v8.0.0, TiDB supports a DML type for handling a large amount of data. This DML type writes data to TiKV in a timely manner during execution, avoiding the continuous storage of all transaction data in memory, and thus supports handling a large amount of data that exceeds the memory limit. This DML type ensures transaction integrity and uses the same syntax as standard DML. `INSERT`, `UPDATE`, `REPLACE`, and `DELETE` statements can use this new DML type to execute large-scale DML operations. + + This DML type is implemented by the [Pipelined DML](https://github.com/pingcap/tidb/blob/master/docs/design/2024-01-09-pipelined-DML.md) feature and only takes effect on statements with auto-commit enabled. You can control whether to enable this DML type by setting the system variable [`tidb_dml_type`](/system-variables.md#tidb_dml_type-new-in-v800). + + For more information, see [documentation](/system-variables.md#tidb_dml_type-new-in-v800). + +* Support using some expressions to set default column values when creating a table (experimental) [#50936](https://github.com/pingcap/tidb/issues/50936) @[zimulala](https://github.com/zimulala) + + Before v8.0.0, when you create a table, the default value of a column is limited to strings, numbers, and dates. Starting from v8.0.0, you can use some expressions as the default column values. For example, you can set the default value of a column to `UUID()`. This feature helps you meet more diverse requirements. + + For more information, see [documentation](/data-type-default-values.md#specify-expressions-as-default-values). + +* Support the `div_precision_increment` system variable [#51501](https://github.com/pingcap/tidb/issues/51501) @[yibin87](https://github.com/yibin87) + + MySQL 8.0 supports the variable `div_precision_increment`, which specifies the number of digits by which to increase the scale of the result of a division operation performed using the `/` operator. Before v8.0.0, TiDB does not support this variable, and division is performed to 4 decimal places. Starting from v8.0.0, TiDB supports this variable. You can specify the number of digits by which to increase the scale of the result of a division operation as desired. + + For more information, see [documentation](/system-variables.md#div_precision_increment-new-in-v800). + +### DB operations + +* PITR supports Amazon S3 Object Lock [#51184](https://github.com/pingcap/tidb/issues/51184) @[RidRisR](https://github.com/RidRisR) + + Amazon S3 Object Lock can help prevent backup data from accidental or intentional deletion during a specified retention period, enhancing the security and integrity of data. Starting from v6.3.0, BR supports Amazon S3 Object Lock for snapshot backups, adding an additional layer of security for full backups. Starting from v8.0.0, PITR also supports Amazon S3 Object Lock. Whether for full backups or log data backups, the Object Lock feature ensures more reliable data protection, further strengthening the security of data backup and recovery and meeting regulatory requirements. + + For more information, see [documentation](/br/backup-and-restore-storages.md#other-features-supported-by-the-storage-service). + +* Support making invisible indexes visible at the session level [#50653](https://github.com/pingcap/tidb/issues/50653) @[hawkingrei](https://github.com/hawkingrei) + + By default, the optimizer does not select [invisible indexes](/sql-statements/sql-statement-create-index.md#invisible-index). This mechanism is usually used to evaluate whether to delete an index. If there is uncertainty about the potential performance impact of deleting an index, you have the option to set the index to invisible temporarily and promptly restore it to visible when needed. + + Starting from v8.0.0, you can set the session-level system variable [`tidb_opt_use_invisible_indexes`](/system-variables.md#tidb_opt_use_invisible_indexes-new-in-v800) to `ON` to make the current session aware of invisible indexes. With this feature, you can create a new index and test its performance by making the index visible first, and then modifying the system variable in the current session for testing without affecting other sessions. This improvement enhances the safety of SQL tuning and helps to improve the stability of production databases. + + For more information, see [documentation](/sql-statements/sql-statement-create-index.md#invisible-index). + +* Support writing general logs to a separate file [#51248](https://github.com/pingcap/tidb/issues/51248) @[Defined2014](https://github.com/Defined2014) + + The general log is a MySQL-compatible feature that logs all executed SQL statements to help diagnose issues. TiDB also supports this feature. You can enable it by setting the variable [`tidb_general_log`](/system-variables.md#tidb_general_log). However, in previous versions, the content of general logs can only be written to the TiDB instance log along with other information, which is inconvenient for users who need to keep logs for a long time. + + Starting from v8.0.0, you can write the general log to a specified file by setting the configuration item [`log.general-log-file`](/tidb-configuration-file.md#general-log-file-new-in-v800) to a valid filename. The general log follows the same rotation and retention policies as the instance log. + + In addition, to reduce the disk space occupied by historical log files, TiDB v8.0.0 introduces a native log compression option. You can set the configuration item [`log.file.compression`](/tidb-configuration-file.md#compression-new-in-v800) to `gzip` to automatically compress rotated logs using the [`gzip`](https://www.gzip.org/) format. + + For more information, see [documentation](/tidb-configuration-file.md#general-log-file-new-in-v800). + +### Observability + +* Support monitoring index usage statistics [#49830](https://github.com/pingcap/tidb/issues/49830) @[YangKeao](https://github.com/YangKeao) + + Proper index design is a crucial prerequisite to maintaining database performance. TiDB v8.0.0 introduces the [`INFORMATION_SCHEMA.TIDB_INDEX_USAGE`](/information-schema/information-schema-tidb-index-usage.md) table, which records the statistics of all indexes on the current TiDB node, including the following information: + + * The cumulative execution count of statements that scan the index + * The total number of rows scanned when accessing the index + * The selectivity distribution when scanning the index + * The time of the most recent access to the index + + With this information, you can identify indexes that are not used by the optimizer and indexes with poor selectivity, thereby optimizing index design to improve database performance. + + Additionally, TiDB v8.0.0 introduces a view [`sys.schema_unused_indexes`](/sys-schema/sys-schema-unused-indexes.md), which is compatible with MySQL. This view shows indexes that have not been used since the last start of TiDB instances. For clusters upgraded from versions earlier than v8.0.0, the `sys` schema and the views are not created automatically. You can manually create them by referring to [`sys.schema_unused_indexes`](/sys-schema/sys-schema-unused-indexes.md#manually-create-the-schema_unused_indexes-view). + + For more information, see [documentation](/information-schema/information-schema-tidb-index-usage.md). + +### Security + +* TiKV encryption at rest supports Google [Key Management Service (Cloud KMS)](https://cloud.google.com/docs/security/key-management-deep-dive?hl) (experimental) [#8906](https://github.com/tikv/tikv/issues/8906) @[glorv](https://github.com/glorv) + + TiKV ensures data security by encrypting stored data using the encryption at rest technique. The core of encryption at rest for security is key management. Starting from v8.0.0, you can manage the master key of TiKV using Google Cloud KMS to establish encryption-at-rest capabilities based on Cloud KMS, thereby enhancing the security of user data. + + To enable encryption at rest based on Google Cloud KMS, you need to create a key on Google Cloud and then configure the `[security.encryption.master-key]` section in the TiKV configuration file. + + For more information, see [documentation](/encryption-at-rest.md#tikv-encryption-at-rest). + +* Enhance TiDB log desensitization [#51306](https://github.com/pingcap/tidb/issues/51306) @[xhebox](https://github.com/xhebox) + + The enhancement of TiDB log desensitization is based on marking SQL text information in log files, facilitating the safe display of sensitive data when users view the logs. You can control whether to desensitize log information to enable secure use of TiDB logs in different scenarios, enhancing the security and flexibility of using log desensitization. To use this feature, set the system variable `tidb_redact_log` to `MARKER`. This marks the SQL text in TiDB logs. When you view the logs, sensitive data is securely displayed based on the markers, thus protecting the log information. + + For more information, see [documentation](/system-variables.md#tidb_redact_log). + +### Data migration + +* TiCDC adds support for the Simple protocol [#9898](https://github.com/pingcap/tiflow/issues/9898) @[3AceShowHand](https://github.com/3AceShowHand) + + TiCDC introduces a new protocol, the Simple protocol. This protocol provides in-band schema tracking capabilities by embedding table schema information in DDL and BOOTSTRAP events. + + For more information, see [documentation](/ticdc/ticdc-simple-protocol.md). + +* TiCDC adds support for the Debezium format protocol [#1799](https://github.com/pingcap/tiflow/issues/1799) @[breezewish](https://github.com/breezewish) + + TiCDC can now publish data change events to a Kafka sink using a protocol that generates event messages in a Debezium style format. This helps to simplify the migration from MySQL to TiDB for users who are currently using Debezium to pull data from MySQL for downstream processing. + + For more information, see [documentation](/ticdc/ticdc-debezium.md). + +* DM supports using a user-provided secret key to encrypt and decrypt passwords of source and target databases [#9492](https://github.com/pingcap/tiflow/issues/9492) @[D3Hunter](https://github.com/D3Hunter) + + In earlier versions, DM uses a built-in fixed secret key with relatively low security. Starting from v8.0.0, you can upload and specify a secret key file for encrypting and decrypting passwords of upstream and downstream databases. In addition, you can replace the secret key file as needed to enhance data security. + + For more information, see [documentation](/dm/dm-customized-secret-key.md). + +* Supports the `IMPORT INTO ... FROM SELECT` syntax to enhance the `IMPORT INTO` functionality (experimental) [#49883](https://github.com/pingcap/tidb/issues/49883) @[D3Hunter](https://github.com/D3Hunter) + + In earlier TiDB versions, importing query results into a target table could only be done using the `INSERT INTO ... SELECT` statement, which is relatively inefficient in some large dataset scenarios. Starting from v8.0.0, TiDB enables you to use `IMPORT INTO ... FROM SELECT` to import the results of a `SELECT` query into an empty TiDB target table, which achieves up to 8 times the performance of `INSERT INTO ... SELECT` and significantly reduces the import time. + + In addition, you can use `IMPORT INTO ... FROM SELECT` to import historical data queried with [`AS OF TIMESTAMP`](/as-of-timestamp.md). + + For more information, see [documentation](/sql-statements/sql-statement-import-into.md). + +* TiDB Lightning simplifies conflict resolution strategies and supports handling conflicting data using the `replace` strategy (experimental) [#51036](https://github.com/pingcap/tidb/issues/51036) @[lyzx2001](https://github.com/lyzx2001) + + In earlier versions, TiDB Lightning has [one data conflict resolution strategy](/tidb-lightning/tidb-lightning-logical-import-mode-usage.md#conflict-detection) for the logical import mode and [two data conflict resolution strategies](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#conflict-detection) for the physical import mode, which are not easy to understand and configure. + + Starting from v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md) parameter, and simplifies the configuration of this parameter. In addition, in the physical import mode, the `replace` strategy now supports retaining the latest data and overwriting the old data when the import detects data with primary key or unique key conflicts. + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md). + +* Global Sort becomes generally available (GA), improving the performance and stability of `IMPORT INTO` significantly [#45719](https://github.com/pingcap/tidb/issues/45719) @[lance6716](https://github.com/lance6716) + + Before v7.4.0, when executing `IMPORT INTO` tasks using the [Distributed eXecution Framework (DXF)](/tidb-distributed-execution-framework.md), TiDB only locally sorts part of the data before importing it into TiKV due to limited local storage space. This results in significant overlap of the imported data in TiKV, requiring TiKV to perform additional compaction operations during import and affecting the TiKV performance and stability. + + With the Global Sort experimental feature introduced in v7.4.0, TiDB can temporarily store the data to be imported in an external storage (such as Amazon S3) for global sorting before importing it into TiKV, which eliminates the need for TiKV compaction operations during import. In v8.0.0, Global Sort becomes GA. This feature reduces the resource consumption of TiKV and significantly improves the performance and stability of `IMPORT INTO`. If you enable the Global Sort, each `IMPORT INTO` task supports importing data within 40 TiB. + + For more information, see [documentation](/tidb-global-sort.md). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v7.6.0 to the current version (v8.0.0). If you are upgrading from v7.5.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +- Upgrade the default Prometheus version deployed by TiUP from 2.27.1 to 2.49.1. +- Upgrade the default Grafana version deployed by TiUP from 7.5.11 to 7.5.17. +- Remove witness-related schedulers that are not GA but are enabled by default [#7765](https://github.com/tikv/pd/pull/7765) @[rleungx](https://github.com/rleungx) + +### Behavior changes + +* Prohibit setting [`require_secure_transport`](/system-variables.md#require_secure_transport-new-in-v610) to `ON` in Security Enhanced Mode (SEM) to prevent potential connectivity issues for users. [#47665](https://github.com/pingcap/tidb/issues/47665) @[tiancaiamao](https://github.com/tiancaiamao) +* DM removes the fixed secret key for encryption and decryption and enables you to customize a secret key for encryption and decryption. If encrypted passwords are used in [data source configurations](/dm/dm-source-configuration-file.md) and [migration task configurations](/dm/task-configuration-file-full.md) before the upgrade, you need to refer to the upgrade steps in [Customize a Secret Key for DM Encryption and Decryption](/dm/dm-customized-secret-key.md) for additional operations. [#9492](https://github.com/pingcap/tiflow/issues/9492) @[D3Hunter](https://github.com/D3Hunter) +* Before v8.0.0, after enabling the acceleration of `ADD INDEX` and `CREATE INDEX` (`tidb_ddl_enable_fast_reorg = ON`), the encoded index key ingests data to TiKV with a fixed concurrency of `16`, which cannot be dynamically adjusted according to the downstream TiKV capacity. Starting from v8.0.0, you can adjust the concurrency using the [`tidb_ddl_reorg_worker_cnt`](/system-variables.md#tidb_ddl_reorg_worker_cnt) system variable. The default value is `4`. Compared with the previous default value of `16`, the new default value reduces performance when ingesting indexed key-value pairs. You can adjust this system variable based on the workload of your cluster. + +### MySQL compatibility + +* The `KEY` partition type supports statements with an empty list of partition fields, which is consistent with the behavior of MySQL. + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_disable_txn_auto_retry`](/system-variables.md#tidb_disable_txn_auto_retry) | Deprecated | Starting from v8.0.0, this system variable is deprecated, and TiDB no longer supports automatic retries of optimistic transactions. It is recommended to use the [Pessimistic transaction mode](/pessimistic-transaction.md). If you encounter optimistic transaction conflicts, you can capture the error and retry transactions in your application. | +| `tidb_ddl_version` | Renamed | Controls whether to enable TiDB DDL V2. Starting from v8.0.0, this variable is renamed to [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800) to better reflect its purpose. | +| [`tidb_enable_collect_execution_info`](/system-variables.md#tidb_enable_collect_execution_info) | Modified | Adds a control to whether to record the [usage statistics of indexes](/information-schema/information-schema-tidb-index-usage.md). The default value is `ON`. | +| [`tidb_redact_log`](/system-variables.md#tidb_redact_log) | Modified | Controls how to handle user information in SAL text when logging TiDB logs and slow logs. The value options are `OFF` (indicating not processing user information in the log) and `ON` (indicating hiding user information in the log). To provide a richer way of processing user information in the log, the `MARKER` option is added in v8.0.0 to support marking log information. | +| [`div_precision_increment`](/system-variables.md#div_precision_increment-new-in-v800) | Newly added | Controls the number of digits by which to increase the scale of the result of a division operation performed using the `/` operator. This variable is the same as MySQL. | +| [`tidb_dml_type`](/system-variables.md#tidb_dml_type-new-in-v800) | Newly added | Controls the execution mode of DML statements. The value options are `"standard"` and `"bulk"`. | +| [`tidb_enable_auto_analyze_priority_queue`](/system-variables.md#tidb_enable_auto_analyze_priority_queue-new-in-v800) | Newly added | Controls whether to enable the priority queue to schedule the tasks of automatically collecting statistics. When this variable is enabled, TiDB prioritizes collecting statistics for the tables that most need statistics. | +| [`tidb_enable_parallel_hashagg_spill`](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800) | Newly added | Controls whether TiDB supports disk spill for the parallel HashAgg algorithm. When it is `ON`, disk spill can be triggered for the parallel HashAgg algorithm. This variable will be deprecated when this feature is generally available in a future release. | +| [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800) | Newly added | Controls whether to enable [TiDB Accerates Table Creation](/accelerated-table-creation.md). Set the value to `ON` to enable it and `OFF` to disable it. The default value is `ON`. When this variable is enabled, TiDB accelerates table creation by using [`CREATE TABLE`](/sql-statements/sql-statement-create-table.md). | +| [`tidb_load_binding_timeout`](/system-variables.md#tidb_load_binding_timeout-new-in-v800) | Newly added | Controls the timeout of loading bindings. If the execution time of loading bindings exceeds this value, the loading will stop. | +| [`tidb_low_resolution_tso_update_interval`](/system-variables.md#tidb_low_resolution_tso_update_interval-new-in-v800) | Newly added | Controls the interval for updating TiDB [cache timestamp](/system-variables.md#tidb_low_resolution_tso). | +| [`tidb_opt_ordering_index_selectivity_ratio`](/system-variables.md#tidb_opt_ordering_index_selectivity_ratio-new-in-v800) | Newly added | Controls the estimated number of rows for an index that matches the SQL statement `ORDER BY` when there are `ORDER BY` and `LIMIT` clauses in a SQL statement, but some filter conditions not covered by the index. The default value is `-1`, which means to disable this system variable. | +| [`tidb_opt_use_invisible_indexes`](/system-variables.md#tidb_opt_use_invisible_indexes-new-in-v800) | Newly added | Controls whether the optimizer can select [invisible indexes](/sql-statements/sql-statement-create-index.md#invisible-index) for query optimization in the current session. When the variable is set to `ON`, the optimizer can select invisible indexes for query optimization in the session. | +| [`tidb_schema_cache_size`](/system-variables.md#tidb_schema_cache_size-new-in-v800) | Newly added | Controls the upper limit of memory that can be used for caching the schema information to avoid occupying too much memory. When this feature is enabled, the LRU algorithm is used to cache the required tables, effectively reducing the memory occupied by the schema information. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`instance.tidb_enable_collect_execution_info`](/tidb-configuration-file.md#tidb_enable_collect_execution_info) | Modified | Adds a control to whether to record the [usage statistics of indexes](/information-schema/information-schema-tidb-index-usage.md). The default value is `true`. | +| TiDB | [`tls-version`](/tidb-configuration-file.md#tls-version) | Modified | This parameter no longer supports `"TLSv1.0"` and `"TLSv1.1"`. Now it only supports `"TLSv1.2"` and `"TLSv1.3"`. | +| TiDB | [`log.file.compression`](/tidb-configuration-file.md#compression-new-in-v800) | Newly added | Specifies the compression format of the polling log. The default value is null, which means that the polling log is not compressed. | +| TiDB | [`log.general-log-file`](/tidb-configuration-file.md#general-log-file-new-in-v800) | Newly added | Specifies the file to save the general log to. The default is null, which means that the general log will be written to the instance file. | +| TiDB | [`tikv-client.enable-replica-selector-v2`](/tidb-configuration-file.md#enable-replica-selector-v2-new-in-v800) | Newly added | Controls whether to use the new version of the Region replica selector when sending RPC requests to TiKV. The default value is `true`. | +| TiKV | [`log-backup.initial-scan-rate-limit`](/tikv-configuration-file.md#initial-scan-rate-limit-new-in-v620) | Modified | Adds a limit of `1MiB` as the minimum value. | +| TiKV | [`raftstore.store-io-pool-size`](/tikv-configuration-file.md#store-io-pool-size-new-in-v530) | Modified | Changes the default value from `0` to `1` to improve TiKV performance, meaning that the size of the StoreWriter thread pool now defaults to `1`. | +| TiKV | [`rocksdb.defaultcf.titan.blob-cache-size`](/tikv-configuration-file.md#blob-cache-size) | Modified | Starting from v8.0.0, TiKV introduces the `shared-blob-cache` configuration item and enables it by default, so there is no need to set `blob-cache-size` separately. The configuration of `blob-cache-size` only takes effect when `shared-blob-cache` is set to `false`. | +| TiKV | [`security.encryption.master-key.vendor`](/encryption-at-rest.md#specify-a-master-key-via-kms) | Modified | Adds `gcp` as an available type for the service provider. | +| TiKV | [`rocksdb.defaultcf.titan.shared-blob-cache`](/tikv-configuration-file.md#shared-blob-cache-new-in-v800) | Newly added | Controls whether to enable the shared cache for Titan blob files and RocksDB block files. The default value is `true`. | +| TiKV | [`security.encryption.master-key.gcp.credential-file-path`](/encryption-at-rest.md#specify-a-master-key-via-kms) | Newly added | Specifies the path to the Google Cloud authentication credentials file when `security.encryption.master-key.vendor` is `gcp`. | +| TiDB Lightning | [`tikv-importer.duplicate-resolution`](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) | Deprecated | Controls whether to detect and resolve unique key conflicts in physical import mode. Starting from v8.0.0, it is replaced by [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task). | +| TiDB Lightning | [`conflict.precheck-conflict-before-import`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Newly added | Controls whether to enable pre-import conflict detection, which checks conflicts in data before importing it to TiDB. The default value of this parameter is `false`, which means that TiDB Lightning only checks conflicts after the data import. This parameter can be used only in the physical import mode (`tikv-importer.backend = "local"`). | +| TiDB Lightning | [`logical-import-batch-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Newly added | Controls the maximum number of rows inserted per transaction in the logical import mode. The default value is `65536` rows. | +| TiDB Lightning | [`logical-import-batch-size`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Newly added | Controls the maximum size of each SQL query executed on the downstream TiDB server in the logical import mode. The default value is `"96KiB"`. The unit can be KB, KiB, MB, or MiB. | +| Data Migration | [`secret-key-path`](/dm/dm-master-configuration-file.md) | Newly added | Specifies the file path of the secret key, which is used to encrypt and decrypt upstream and downstream passwords. The file must contain a 64-character hexadecimal AES-256 secret key. | +| TiCDC | [`tls-certificate-file`](/ticdc/ticdc-sink-to-pulsar.md) | Newly added | Specifies the path to the encrypted certificate file on the client, which is required when Pulsar enables TLS encrypted transmission. | +| TiCDC | [`tls-key-file-path`](/ticdc/ticdc-sink-to-pulsar.md) | Newly added | Specifies the path to the encrypted private key on the client, which is required when Pulsar enables TLS encrypted transmission. | + +### System tables + +* Add new system tables [`INFORMATION_SCHEMA.TIDB_INDEX_USAGE`](/information-schema/information-schema-tidb-index-usage.md) and [`INFORMATION_SCHEMA.CLUSTER_TIDB_INDEX_USAGE`](/information-schema/information-schema-tidb-index-usage.md#cluster_tidb_index_usage) to record index usage statistics on TiDB nodes. +* Add a new system schema [`sys`](/sys-schema/sys-schema.md) and a new view [`sys.schema_unused_indexes`](/sys-schema/sys-schema-unused-indexes.md), which records indexes that have not been used since the last start of TiDB. + +## Deprecated features + +- Starting from v8.0.0, the [`tidb_disable_txn_auto_retry`](/system-variables.md#tidb_disable_txn_auto_retry) system variable is deprecated, and TiDB no longer supports automatic retries of optimistic transactions. As an alternative, when encountering optimistic transaction conflicts, you can capture the error and retry transactions in your application, or use the [Pessimistic transaction mode](/pessimistic-transaction.md) instead. +- Starting from v8.0.0, TiDB no longer supports the TLSv1.0 and TLSv1.1 protocols. You must upgrade TLS to TLSv1.2 or TLSv1.3. +- Starting from v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, and enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md) parameter. The [`duplicate-resolution`](/tidb-lightning/tidb-lightning-configuration.md) parameter for the old version of conflict detection will be removed in a future release. +- It is planned to redesign [the auto-evolution of execution plan bindings](/sql-plan-management.md#baseline-evolution) in subsequent releases, and the related variables and behavior will change. + +## Improvements + ++ TiDB + + - Improve the performance of executing the `CREATE TABLE` DDL statement by 10 times and support linear scalability [#50052](https://github.com/pingcap/tidb/issues/50052) @[GMHDBJD](https://github.com/GMHDBJD) + - Support submitting 16 `IMPORT INTO ... FROM FILE` tasks simultaneously, facilitating bulk data import into target tables and significantly improving the efficiency and performance of importing data files [#49008](https://github.com/pingcap/tidb/issues/49008) @[D3Hunter](https://github.com/D3Hunter) + - Improve the performance of spilling data to disk for the `Sort` operator [#47733](https://github.com/pingcap/tidb/issues/47733) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Support canceling queries during spilling data to disk, which optimizes the exit mechanism of the data spill feature [#50511](https://github.com/pingcap/tidb/issues/50511) @[wshwsh12](https://github.com/wshwsh12) + - Support using an index that matches partial conditions to construct Index Join when processing table join queries with multiple equal conditions [#47233](https://github.com/pingcap/tidb/issues/47233) @[winoros](https://github.com/winoros) + - Enhance the capability of Index Merge to identify sorting requirements in queries and select indexes that meet the sorting requirements [#48359](https://github.com/pingcap/tidb/issues/48359) @[AilinKid](https://github.com/AilinKid) + - When the `Apply` operator is not executed concurrently, TiDB enables you to view the name of the operator that blocks the concurrency by executing `SHOW WARNINGS` [#50256](https://github.com/pingcap/tidb/issues/50256) @[hawkingrei](https://github.com/hawkingrei) + - Optimize the index selection for `point get` queries by selecting the most optimal index for queries when all indexes support `point get` queries [#50184](https://github.com/pingcap/tidb/issues/50184) @[elsa0520](https://github.com/elsa0520) + - Temporarily adjust the priority of statistics synchronously loading tasks to high to avoid widespread timeouts during TiKV high loads, as these timeouts might result in statistics not being loaded [#50332](https://github.com/pingcap/tidb/issues/50332) @[winoros](https://github.com/winoros) + - When the `PREPARE` statement fails to hit the execution plan cache, TiDB enables you to view the reason by executing `SHOW WARNINGS` [#50407](https://github.com/pingcap/tidb/issues/50407) @[hawkingrei](https://github.com/hawkingrei) + - Improve the accuracy of query estimation information when the same row of data is updated multiple times [#47523](https://github.com/pingcap/tidb/issues/47523) @[terry1purcell](https://github.com/terry1purcell) + - Index Merge supports embedding multi-value indexes and `OR` operators in `AND` predicates [#51778](https://github.com/pingcap/tidb/issues/51778) @[time-and-fate](https://github.com/time-and-fate) + - When `force-init-stats` is set to `true`, TiDB waits for statistics initialization to finish before providing services during TiDB startup. This setting no longer blocks the startup of HTTP servers, which enables users to continue monitoring [#50854](https://github.com/pingcap/tidb/issues/50854) @[hawkingrei](https://github.com/hawkingrei) + - MemoryTracker can track the memory usage of the `IndexLookup` operator [#45901](https://github.com/pingcap/tidb/issues/45901) @[solotzg](https://github.com/solotzg) + - MemoryTracker can track the memory usage of the `MemTableReaderExec` operator [#51456](https://github.com/pingcap/tidb/issues/51456) @[wshwsh12](https://github.com/wshwsh12) + - Support loading Regions in batch from PD to speed up the conversion process from the KV range to Regions when querying large tables [#51326](https://github.com/pingcap/tidb/issues/51326) @[SeaRise](https://github.com/SeaRise) + - Optimize the query performance of the system tables `INFORMATION_SCHEMA.TABLES`, `INFORMATION_SCHEMA.STATISTICS`, `INFORMATION_SCHEMA.KEY_COLUMN_USAGE`, and `INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS`. Compared with earlier versions, the performance has been improved by up to 100 times. [#50305](https://github.com/pingcap/tidb/issues/50305) @[ywqzzy](https://github.com/ywqzzy) + ++ TiKV + + - Enhance TSO verification and detection to improve the robustness of the cluster TSO when the configuration or operation is improper [#16545](https://github.com/tikv/tikv/issues/16545) @[cfzjywxk](https://github.com/cfzjywxk) + - Optimize the logic of cleaning up pessimistic locks to improve the processing performance of uncommitted transactions [#16158](https://github.com/tikv/tikv/issues/16158) @[cfzjywxk](https://github.com/cfzjywxk) + - Introduce unified health control for TiKV to reduce the impact of abnormal single TiKV node on cluster access performance. You can disable this optimization by setting [`tikv-client.enable-replica-selector-v2`](/tidb-configuration-file.md#enable-replica-selector-v2-new-in-v800) to `false`. [#16297](https://github.com/tikv/tikv/issues/16297) [#1104](https://github.com/tikv/client-go/issues/1104) [#1167](https://github.com/tikv/client-go/issues/1167) @[MyonKeminta](https://github.com/MyonKeminta) @[zyguan](https://github.com/zyguan) @[crazycs520](https://github.com/crazycs520) + - The PD client uses the metadata storage interface to replace the previous global configuration interface [#14484](https://github.com/tikv/tikv/issues/14484) @[HuSharp](https://github.com/HuSharp) + - Enhance the scanning performance by determining the data loading behavior through write cf stats [#16245](https://github.com/tikv/tikv/issues/16245) @[Connor1996](https://github.com/Connor1996) + - Check the latest heartbeat for nodes being deleted and voters being demoted during the Raft conf change process to ensure that this behavior does not make the Region inaccessible [#15799](https://github.com/tikv/tikv/issues/15799) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Add Flush and BufferBatchGet interfaces for Pipelined DML [#16291](https://github.com/tikv/tikv/issues/16291) @[ekexium](https://github.com/ekexium) + - Add monitoring and alerting for cgroup CPU and memory limits [#16392](https://github.com/tikv/tikv/issues/16392) @[pingandb](https://github.com/pingandb) + - Add CPU monitoring for Region workers and snapshot generation workers [#16562](https://github.com/tikv/tikv/issues/16562) @[Connor1996](https://github.com/Connor1996) + - Add slow logs for peer and store messages [#16600](https://github.com/tikv/tikv/issues/16600) @[Connor1996](https://github.com/Connor1996) + ++ PD + + - Enhance the service discovery capability of the PD client to improve its high availability and load balancing [#7576](https://github.com/tikv/pd/issues/7576) @[CabinfeverB](https://github.com/CabinfeverB) + - Enhance the retry mechanism of the PD client [#7673](https://github.com/tikv/pd/issues/7673) @[JmPotato](https://github.com/JmPotato) + - Add monitoring and alerting for cgroup CPU and memory limits [#7716](https://github.com/tikv/pd/issues/7716) [#7918](https://github.com/tikv/pd/issues/7918) @[pingandb](https://github.com/pingandb) @[rleungx](https://github.com/rleungx) + - Improve the performance and high availability when using etcd watch [#7738](https://github.com/tikv/pd/issues/7738) [#7724](https://github.com/tikv/pd/issues/7724) [#7689](https://github.com/tikv/pd/issues/7689) @[lhy1024](https://github.com/lhy1024) + - Add more monitoring metrics for heartbeat to better analyze performance bottlenecks [#7868](https://github.com/tikv/pd/issues/7868) @[nolouch](https://github.com/nolouch) + - Reduce the impact of the etcd leader on the PD leader [#7499](https://github.com/tikv/pd/issues/7499) @[JmPotato](https://github.com/JmPotato) @[HuSharp](https://github.com/HuSharp) + - Enhance the detection mechanism for unhealthy etcd nodes [#7730](https://github.com/tikv/pd/issues/7730) @[JmPotato](https://github.com/JmPotato) @[HuSharp](https://github.com/HuSharp) + - Optimize the output of GC safepoint in pd-ctl [#7767](https://github.com/tikv/pd/issues/7767) @[nolouch](https://github.com/nolouch) + - Support dynamic modification of the historical window configuration in the hotspot scheduler [#7877](https://github.com/tikv/pd/issues/7877) @[lhy1024](https://github.com/lhy1024) + - Reduce the lock contention issue in creating operators [#7837](https://github.com/tikv/pd/issues/7837) @[Leavrth](https://github.com/Leavrth) + - Adjust GRPC configurations to improve availability [#7821](https://github.com/tikv/pd/issues/7821) @[rleungx](https://github.com/rleungx) + ++ TiFlash + + - Support using non-constant values for the `json_path` argument in the `JSON_EXTRACT()` function [#8510](https://github.com/pingcap/tiflash/issues/8510) @[SeaRise](https://github.com/SeaRise) + - Support the `JSON_LENGTH(json, path)` function [#8711](https://github.com/pingcap/tiflash/issues/8711) @[SeaRise](https://github.com/SeaRise) + ++ Tools + + + Backup & Restore (BR) + + - Introduce a new restore parameter `--load-stats` for the `br` command-line tool, which controls whether to restore statistics [#50568](https://github.com/pingcap/tidb/issues/50568) @[Leavrth](https://github.com/Leavrth) + - Introduce a new restore parameter `--tikv-max-restore-concurrency` for the `br` command-line tool, which controls the maximum number of download and ingest files for each TiKV node. This parameter also controls the memory consumption of a BR node by controlling the maximum length of the job queue. [#51621](https://github.com/pingcap/tidb/issues/51621) @[3pointer](https://github.com/3pointer) + - Enhance restore performance by enabling the coarse-grained Region scatter algorithm to adaptively obtain concurrent parameters [#50701](https://github.com/pingcap/tidb/issues/50701) @[3pointer](https://github.com/3pointer) + - Display the `log` command in the command-line help information of `br` [#50927](https://github.com/pingcap/tidb/issues/50927) @[RidRisR](https://github.com/RidRisR) + - Support pre-allocating Table ID during the restore process to maximize the reuse of Table ID and improve restore performance [#51736](https://github.com/pingcap/tidb/issues/51736) @[Leavrth](https://github.com/Leavrth) + - Disable the GC memory limit tuner feature within TiDB when using BR to avoid OOM issues [#51078](https://github.com/pingcap/tidb/issues/51078) @[Leavrth](https://github.com/Leavrth) + - Improve the speed of merging SST files during data restore by using a more efficient algorithm [#50613](https://github.com/pingcap/tidb/issues/50613) @[Leavrth](https://github.com/Leavrth) + - Support creating databases in batch during data restore [#50767](https://github.com/pingcap/tidb/issues/50767) @[Leavrth](https://github.com/Leavrth) + - Print the information of the slowest Region that affects global checkpoint advancement in logs and metrics during log backups [#51046](https://github.com/pingcap/tidb/issues/51046) @[YuJuncen](https://github.com/YuJuncen) + - Improve the table creation performance of the `RESTORE` statement in scenarios with large datasets [#48301](https://github.com/pingcap/tidb/issues/48301) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Optimize the memory consumption of `RowChangedEvent` to reduce memory consumption when TiCDC replicates data [#10386](https://github.com/pingcap/tiflow/issues/10386) @[lidezhu](https://github.com/lidezhu) + - Verify that the start-ts parameter is valid when creating and resuming a changefeed task [#10499](https://github.com/pingcap/tiflow/issues/10499) @[3AceShowHand](https://github.com/3AceShowHand) + + + TiDB Data Migration (DM) + + - In a MariaDB primary-secondary replication scenario, where the migration path is: MariaDB primary instance -> MariaDB secondary instance -> DM -> TiDB, when `gtid_strict_mode = off` and the GTID of the MariaDB secondary instance is not strictly incrementing (for example, there is data writing to the MariaDB secondary instance), the DM task will report an error `less than global checkpoint position`. Starting from v8.0.0, TiDB is compatible with this scenario and data can be migrated downstream normally. [#10741](https://github.com/pingcap/tiflow/issues/10741) @[okJiang](https://github.com/okJiang) + + + TiDB Lightning + + - Support configuring the maximum number of rows in a batch in logical import mode using [`logical-import-batch-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) [#46607](https://github.com/pingcap/tidb/issues/46607) @[kennytm](https://github.com/kennytm) + - TiDB Lightning reports an error when the space of TiFlash is insufficient [#50324](https://github.com/pingcap/tidb/issues/50324) @[okJiang](https://github.com/okJiang) + +## Bug fixes + ++ TiDB + + - Fix the issue that `auto analyze` is triggered multiple times when there is no data change [#51775](https://github.com/pingcap/tidb/issues/51775) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `auto analyze` concurrency is set incorrectly [#51749](https://github.com/pingcap/tidb/issues/51749) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue of index inconsistency caused by adding multiple indexes using a single SQL statement [#51746](https://github.com/pingcap/tidb/issues/51746) @[tangenta](https://github.com/tangenta) + - Fix the `Column ... in from clause is ambiguous` error that might occur when a query uses `NATURAL JOIN` [#32044](https://github.com/pingcap/tidb/issues/32044) @[AilinKid](https://github.com/AilinKid) + - Fix the issue of wrong query results due to TiDB incorrectly eliminating constant values in `group by` [#38756](https://github.com/pingcap/tidb/issues/38756) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `LEADING` hint does not take effect in `UNION ALL` statements [#50067](https://github.com/pingcap/tidb/issues/50067) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that `BIT` type columns might cause query errors due to decode failures when they are involved in calculations of some functions [#49566](https://github.com/pingcap/tidb/issues/49566) [#50850](https://github.com/pingcap/tidb/issues/50850) [#50855](https://github.com/pingcap/tidb/issues/50855) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that TiDB might panic when performing a rolling upgrade using `tiup cluster upgrade/start` due to an interaction issue with PD [#50152](https://github.com/pingcap/tidb/issues/50152) @[zimulala](https://github.com/zimulala) + - Fix the issue that executing `UNIQUE` index lookup with an `ORDER BY` clause might cause an error [#49920](https://github.com/pingcap/tidb/issues/49920) @[jackysp](https://github.com/jackysp) + - Fix the issue that TiDB returns wrong query results when processing `ENUM` or `SET` types by constant propagation [#49440](https://github.com/pingcap/tidb/issues/49440) @[winoros](https://github.com/winoros) + - Fix the issue that TiDB might panic when a query contains the Apply operator and the `fatal error: concurrent map writes` error occurs [#50347](https://github.com/pingcap/tidb/issues/50347) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that the control of `SET_VAR` for variables of the string type might become invalid [#50507](https://github.com/pingcap/tidb/issues/50507) @[qw4990](https://github.com/qw4990) + - Fix the issue that the `SYSDATE()` function incorrectly uses the time in the plan cache when `tidb_sysdate_is_now` is set to `1` [#49299](https://github.com/pingcap/tidb/issues/49299) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that when executing the `CREATE GLOBAL BINDING` statement, if the schema name is in uppercase, the binding does not take effect [#50646](https://github.com/pingcap/tidb/issues/50646) @[qw4990](https://github.com/qw4990) + - Fix the issue that `Index Path` selects duplicated indexes [#50496](https://github.com/pingcap/tidb/issues/50496) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `PLAN REPLAYER` fails to load bindings when the `CREATE GLOBAL BINDING` statement contains `IN()` [#43192](https://github.com/pingcap/tidb/issues/43192) @[King-Dylan](https://github.com/King-Dylan) + - Fix the issue that when multiple `analyze` tasks fail, the failure reasons are not recorded correctly [#50481](https://github.com/pingcap/tidb/issues/50481) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that `tidb_stats_load_sync_wait` does not take effect [#50872](https://github.com/pingcap/tidb/issues/50872) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that `max_execute_time` settings at multiple levels interfere with each other [#50914](https://github.com/pingcap/tidb/issues/50914) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue of thread safety caused by concurrent updating of statistics [#50835](https://github.com/pingcap/tidb/issues/50835) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that executing `auto analyze` on a partition table might cause TiDB to panic [#51187](https://github.com/pingcap/tidb/issues/51187) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that SQL bindings might not work when `IN()` in a SQL statement contains a different number of values [#51222](https://github.com/pingcap/tidb/issues/51222) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that TiDB cannot correctly convert the type of a system variable in an expression [#43527](https://github.com/pingcap/tidb/issues/43527) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiDB does not listen to the corresponding port when `force-init-stats` is configured [#51473](https://github.com/pingcap/tidb/issues/51473) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that in `determinate` mode (`tidb_opt_objective='determinate'`), if a query does not contain predicates, statistics might not be loaded [#48257](https://github.com/pingcap/tidb/issues/48257) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that the `init-stats` process might cause TiDB to panic and the `load stats` process to quit [#51581](https://github.com/pingcap/tidb/issues/51581) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the query result is incorrect when the `IN()` predicate contains `NULL` [#51560](https://github.com/pingcap/tidb/issues/51560) @[winoros](https://github.com/winoros) + - Fix the issue that blocked DDL statements are not displayed in the MDL View when a DDL task involves multiple tables [#47743](https://github.com/pingcap/tidb/issues/47743) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the `processed_rows` of the `ANALYZE` task on a table might exceed the total number of rows in that table [#50632](https://github.com/pingcap/tidb/issues/50632) @[hawkingrei](https://github.com/hawkingrei) + - Fix the goroutine leak issue that might occur when the `HashJoin` operator fails to spill to disk [#50841](https://github.com/pingcap/tidb/issues/50841) @[wshwsh12](https://github.com/wshwsh12) + - Fix the goroutine leak issue that occurs when the memory usage of CTE queries exceed limits [#50337](https://github.com/pingcap/tidb/issues/50337) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the `Can't find column ...` error that might occur when aggregate functions are used for group calculations [#50926](https://github.com/pingcap/tidb/issues/50926) @[qw4990](https://github.com/qw4990) + - Fix the issue that DDL operations such as renaming tables are stuck when the `CREATE TABLE` statement contains specific partitions or constraints [#50972](https://github.com/pingcap/tidb/issues/50972) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the monitoring metric `tidb_statistics_auto_analyze_total` on Grafana is not displayed as an integer [#51051](https://github.com/pingcap/tidb/issues/51051) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `tidb_gogc_tuner_threshold` system variable is not adjusted accordingly after the `tidb_server_memory_limit` variable is modified [#48180](https://github.com/pingcap/tidb/issues/48180) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `index out of range` error might occur when a query involves JOIN operations [#42588](https://github.com/pingcap/tidb/issues/42588) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that getting the default value of a column returns an error if the column default value is dropped [#50043](https://github.com/pingcap/tidb/issues/50043) [#51324](https://github.com/pingcap/tidb/issues/51324) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that wrong results might be returned when TiFlash late materialization processes associated columns [#49241](https://github.com/pingcap/tidb/issues/49241) [#51204](https://github.com/pingcap/tidb/issues/51204) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that the `LIKE()` function might return wrong results when processing binary collation inputs [#50393](https://github.com/pingcap/tidb/issues/50393) @[yibin87](https://github.com/yibin87) + - Fix the issue that the `JSON_LENGTH()` function returns wrong results when the second parameter is `NULL` [#50931](https://github.com/pingcap/tidb/issues/50931) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that `CAST(AS DATETIME)` might lose time precision under certain circumstances [#49555](https://github.com/pingcap/tidb/issues/49555) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that parallel `Apply` might generate incorrect results when the table has a clustered index [#51372](https://github.com/pingcap/tidb/issues/51372) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that `ALTER TABLE ... COMPACT TIFLASH REPLICA` might incorrectly end when the primary key type is `VARCHAR` [#51810](https://github.com/pingcap/tidb/issues/51810) @[breezewish](https://github.com/breezewish) + - Fix the issue that the check on the `NULL` value of the `DEFAULT NULL` attribute is incorrect when exchanging partitioned tables using the `EXCHANGE PARTITION` statement [#47167](https://github.com/pingcap/tidb/issues/47167) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the partition table definition might cause wrong behavior when using a non-UTF8 character set [#49251](https://github.com/pingcap/tidb/issues/49251) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that incorrect default values are displayed in the `INFORMATION_SCHEMA.VARIABLES_INFO` table for some system variables [#49461](https://github.com/pingcap/tidb/issues/49461) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that no error is reported when empty strings are used as database names in some cases [#45873](https://github.com/pingcap/tidb/issues/45873) @[yoshikipom](https://github.com/yoshikipom) + - Fix the issue that the `SPLIT TABLE ... INDEX` statement might cause TiDB to panic [#50177](https://github.com/pingcap/tidb/issues/50177) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that querying a partitioned table of `KeyPartition` type might cause an error [#50206](https://github.com/pingcap/tidb/issues/50206) [#51313](https://github.com/pingcap/tidb/issues/51313) [#51196](https://github.com/pingcap/tidb/issues/51196) @[time-and-fate](https://github.com/time-and-fate) @[jiyfhust](https://github.com/jiyfhust) @[mjonss](https://github.com/mjonss) + - Fix the issue that querying a Hash partitioned table might produce incorrect results [#50427](https://github.com/pingcap/tidb/issues/50427) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that opentracing does not work correctly [#50508](https://github.com/pingcap/tidb/issues/50508) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the error message is not complete when `ALTER INSTANCE RELOAD TLS` reports an error [#50699](https://github.com/pingcap/tidb/issues/50699) @[dveeden](https://github.com/dveeden) + - Fix the issue that the `AUTO_INCREMENT` attribute causes non-consecutive IDs due to unnecessary transaction conflicts when assigning auto-increment IDs [#50819](https://github.com/pingcap/tidb/issues/50819) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue of incomplete stack information in TiDB logs for some errors [#50849](https://github.com/pingcap/tidb/issues/50849) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue of excessive memory usage in some queries when the number in the `LIMIT` clause is too large [#51188](https://github.com/pingcap/tidb/issues/51188) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the TTL feature causes data hotspots due to incorrect data range splitting in some cases [#51527](https://github.com/pingcap/tidb/issues/51527) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the `SET` statement does not take effect when it appears on the first line of an explicit transaction [#51387](https://github.com/pingcap/tidb/issues/51387) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that querying JSON of `BINARY` type might cause an error in some cases [#51547](https://github.com/pingcap/tidb/issues/51547) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that TTL does not handle the transition for daylight saving time adjustments correctly when calculating expiration times [#51675](https://github.com/pingcap/tidb/issues/51675) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the `SURVIVAL_PREFERENCES` attribute might not appear in the output of the `SHOW CREATE PLACEMENT POLICY` statement under certain conditions [#51699](https://github.com/pingcap/tidb/issues/51699) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the configuration file does not take effect when it contains an invalid configuration item [#51399](https://github.com/pingcap/tidb/issues/51399) @[Defined2014](https://github.com/Defined2014) + ++ TiKV + + - Fix the issue that enabling `tidb_enable_row_level_checksum` might cause TiKV to panic [#16371](https://github.com/tikv/tikv/issues/16371) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that hibernated Regions are not promptly awakened in exceptional circumstances [#16368](https://github.com/tikv/tikv/issues/16368) @[LykxSassinator](https://github.com/LykxSassinator) + - Fix the issue that the entire Region becomes unavailable when one replica is offline, by checking the last heartbeat time of all replicas of the Region before taking a node offline [#16465](https://github.com/tikv/tikv/issues/16465) @[tonyxuqqi](https://github.com/tonyxuqqi) + - Fix the issue that JSON integers greater than the maximum `INT64` value but less than the maximum `UINT64` value are parsed as `FLOAT64` by TiKV, resulting in inconsistency with TiDB [#16512](https://github.com/tikv/tikv/issues/16512) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the monitoring metric `tikv_unified_read_pool_thread_count` has no data in some cases [#16629](https://github.com/tikv/tikv/issues/16629) @[YuJuncen](https://github.com/YuJuncen) + ++ PD + + - Fix the issue that data race occurs when the `MergeLabels` function is called [#7535](https://github.com/tikv/pd/issues/7535) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that there is no output when the `evict-leader-scheduler` interface is called [#7672](https://github.com/tikv/pd/issues/7672) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that the PD monitoring item `learner-peer-count` does not synchronize the old value after a leader switch [#7728](https://github.com/tikv/pd/issues/7728) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the memory leak issue that occurs when `watch etcd` is not turned off correctly [#7807](https://github.com/tikv/pd/issues/7807) @[rleungx](https://github.com/rleungx) + - Fix the issue that some TSO logs do not print the error cause [#7496](https://github.com/tikv/pd/issues/7496) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that there are unexpected negative monitoring metrics after restart [#4489](https://github.com/tikv/pd/issues/4489) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that the Leader lease expires later than the log time [#7700](https://github.com/tikv/pd/issues/7700) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that TiDB panics when TLS switches between TiDB (the PD client) and PD are inconsistent [#7900](https://github.com/tikv/pd/issues/7900) [#7902](https://github.com/tikv/pd/issues/7902) [#7916](https://github.com/tikv/pd/issues/7916) @[CabinfeverB](https://github.com/CabinfeverB) + - Fix the issue that Goroutine leaks when it is not closed properly [#7782](https://github.com/tikv/pd/issues/7782) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that pd-ctl cannot remove a scheduler that contains special characters [#7798](https://github.com/tikv/pd/issues/7798) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the PD client might be blocked when obtaining TSO [#7864](https://github.com/tikv/pd/issues/7864) @[CabinfeverB](https://github.com/CabinfeverB) + ++ TiFlash + + - Fix the issue that TiFlash might panic due to unstable network connections with PD during replica migration [#8323](https://github.com/pingcap/tiflash/issues/8323) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that the memory usage increases significantly due to slow queries [#8564](https://github.com/pingcap/tiflash/issues/8564) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that removing and then re-adding TiFlash replicas might lead to data corruption in TiFlash [#8695](https://github.com/pingcap/tiflash/issues/8695) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash replica data might be accidentally deleted after performing point-in-time recovery (PITR) or executing `FLASHBACK CLUSTER TO`, which might result in data anomalies [#8777](https://github.com/pingcap/tiflash/issues/8777) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash panics after executing `ALTER TABLE ... MODIFY COLUMN ... NOT NULL`, which changes nullable columns to non-nullable [#8419](https://github.com/pingcap/tiflash/issues/8419) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that in the disaggregated storage and compute architecture, queries might be permanently blocked after network isolation [#8806](https://github.com/pingcap/tiflash/issues/8806) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that in the disaggregated storage and compute architecture, TiFlash might panic during shutdown [#8837](https://github.com/pingcap/tiflash/issues/8837) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might crash due to data race in case of remote reads [#8685](https://github.com/pingcap/tiflash/issues/8685) @[solotzg](https://github.com/solotzg) + - Fix the issue that the `CAST(AS JSON)` function does not de-duplicate the JSON object key [#8712](https://github.com/pingcap/tiflash/issues/8712) @[SeaRise](https://github.com/SeaRise) + - Fix the issue that the `ENUM` column might cause TiFlash to crash during chunk encoding [#8674](https://github.com/pingcap/tiflash/issues/8674) @[yibin87](https://github.com/yibin87) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that the log backup checkpoint gets stuck when a Region is split or merged immediately after it becomes a leader [#16469](https://github.com/tikv/tikv/issues/16469) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiKV panics when a full backup fails to find a peer in some extreme cases [#16394](https://github.com/tikv/tikv/issues/16394) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that log backup gets stuck after changing the TiKV IP address on the same node [#50445](https://github.com/pingcap/tidb/issues/50445) @[3pointer](https://github.com/3pointer) + - Fix the issue that BR cannot retry when encountering an error while reading file content from S3 [#49942](https://github.com/pingcap/tidb/issues/49942) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that when resuming from a checkpoint after data restore fails, an error `the target cluster is not fresh` occurs [#50232](https://github.com/pingcap/tidb/issues/50232) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that stopping a log backup task causes TiDB to crash [#50839](https://github.com/pingcap/tidb/issues/50839) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that data restore is slowed down due to absence of a leader on a TiKV node [#50566](https://github.com/pingcap/tidb/issues/50566) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that full restore still requires the target cluster to be empty after the `--filter` option is specified [#51009](https://github.com/pingcap/tidb/issues/51009) @[3pointer](https://github.com/3pointer) + + + TiCDC + + - Fix the issue that the file sequence number generated by the storage service might not increment correctly when using the storage sink [#10352](https://github.com/pingcap/tiflow/issues/10352) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that TiCDC returns the `ErrChangeFeedAlreadyExists` error when concurrently creating multiple changefeeds [#10430](https://github.com/pingcap/tiflow/issues/10430) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that after filtering out `add table partition` events is configured in `ignore-event`, TiCDC does not replicate other types of DML changes for related partitions to the downstream [#10524](https://github.com/pingcap/tiflow/issues/10524) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Fix the issue that the changefeed reports an error after `TRUNCATE PARTITION` is executed on the upstream table [#10522](https://github.com/pingcap/tiflow/issues/10522) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that `snapshot lost caused by GC` is not reported in time when resuming a changefeed and the `checkpoint-ts` of the changefeed is smaller than the GC safepoint of TiDB [#10463](https://github.com/pingcap/tiflow/issues/10463) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that TiCDC fails to validate `TIMESTAMP` type checksum due to time zone mismatch after data integrity validation for single-row data is enabled [#10573](https://github.com/pingcap/tiflow/issues/10573) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that the Syncpoint table might be incorrectly replicated [#10576](https://github.com/pingcap/tiflow/issues/10576) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that OAuth2.0, TLS, and mTLS cannot be enabled properly when using Apache Pulsar as the downstream [#10602](https://github.com/pingcap/tiflow/issues/10602) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that a changefeed might get stuck when TiKV upgrades, restarts, or evicts a leader [#10584](https://github.com/pingcap/tiflow/issues/10584) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that data is written to a wrong CSV file due to wrong BarrierTS in scenarios where DDL statements are executed frequently [#10668](https://github.com/pingcap/tiflow/issues/10668) @[lidezhu](https://github.com/lidezhu) + - Fix the issue that data race in the KV client causes TiCDC to panic [#10718](https://github.com/pingcap/tiflow/issues/10718) @[asddongmen](https://github.com/asddongmen) + - Fix the issue TiCDC panics when scheduling table replication tasks [#10613](https://github.com/pingcap/tiflow/issues/10613) @[CharlesCheung96](https://github.com/CharlesCheung96) + + + TiDB Data Migration (DM) + + - Fix the issue that data is lost when the upstream primary key is of binary type [#10672](https://github.com/pingcap/tiflow/issues/10672) @[GMHDBJD](https://github.com/GMHDBJD) + + + TiDB Lightning + + - Fix the performance regression issue caused by checking TiKV space [#43636](https://github.com/pingcap/tidb/issues/43636) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB Lightning reports an error when encountering invalid symbolic link files during file scanning [#49423](https://github.com/pingcap/tidb/issues/49423) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB Lightning fails to correctly parse date values containing `0` when `NO_ZERO_IN_DATE` is not included in `sql_mode` [#50757](https://github.com/pingcap/tidb/issues/50757) @[GMHDBJD](https://github.com/GMHDBJD) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [Aoang](https://github.com/Aoang) +- [bufferflies](https://github.com/bufferflies) +- [daemon365](https://github.com/daemon365) +- [eltociear](https://github.com/eltociear) +- [lichunzhu](https://github.com/lichunzhu) +- [jiyfhust](https://github.com/jiyfhust) +- [pingandb](https://github.com/pingandb) +- [shenqidebaozi](https://github.com/shenqidebaozi) +- [Smityz](https://github.com/Smityz) +- [songzhibin97](https://github.com/songzhibin97) +- [tangjingyu97](https://github.com/tangjingyu97) +- [Tema](https://github.com/Tema) +- [ub-3](https://github.com/ub-3) +- [yoshikipom](https://github.com/yoshikipom) diff --git a/releases/release-8.1.0.md b/releases/release-8.1.0.md new file mode 100644 index 0000000000000..a84c2b268934a --- /dev/null +++ b/releases/release-8.1.0.md @@ -0,0 +1,360 @@ +--- +title: TiDB 8.1.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 8.1.0. +--- + +# TiDB 8.1.0 Release Notes + + + +Release date: May 24, 2024 + +TiDB version: 8.1.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v8.1/quick-start-with-tidb) | [Production deployment](https://docs.pingcap.com/tidb/v8.1/production-deployment-using-tiup) + +TiDB 8.1.0 is a Long-Term Support Release (LTS). + +Compared with the previous LTS 7.5.0, 8.1.0 includes new features, improvements, and bug fixes released in [7.6.0-DMR](/releases/release-7.6.0.md) and [8.0.0-DMR](/releases/release-8.0.0.md). When you upgrade from 7.5.x to 8.1.0, you can download the [TiDB Release Notes PDF](https://download.pingcap.org/tidb-v7.6-to-v8.1-en-release-notes.pdf) to view all release notes between the two LTS versions. The following table lists some highlights from 7.6.0 to 8.1.0: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeature/EnhancementDescription
Scalability and PerformanceAcceleration of cluster snapshot restore speed (GA in v8.0.0)With this feature, BR can fully leverage the scale advantage of a cluster, enabling all TiKV nodes in the cluster to participate in the preparation step of data restores. This feature can significantly improve the restore speed of large datasets in large-scale clusters. Real-world tests show that this feature can saturate the download bandwidth, with the download speed improving by 8 to 10 times, and the end-to-end restore speed improving by approximately 1.5 to 3 times.
Achieve up to 10 times faster for creating tables in batch (experimental, introduced in v7.6.0)With the implementation of the new DDL architecture in v7.6.0, the performance of batch table creation has witnessed a remarkable improvement, up to 10 times faster. This substantial enhancement drastically reduces the time needed for creating numerous tables. This acceleration is particularly noteworthy in SaaS scenarios, where the prevalence of high volumes of tables, ranging from tens to hundreds of thousands, is a common challenge.
Use Active PD Followers to enhance PD's Region information query service (experimental, introduced in v7.6.0)TiDB v7.6.0 introduces an experimental feature "Active PD Follower", which allows PD followers to provide Region information query services. This feature improves the capability of the PD cluster to handle GetRegion and ScanRegions requests in clusters with a large number of TiDB nodes and Regions, thereby reducing the CPU pressure on PD leaders.
Bulk DML for much larger transactions (experimental, introduced in v8.0.0)Large batch DML jobs, such as extensive cleanup jobs, joins, or aggregations, can consume a significant amount of memory and have previously been limited at very large scales. Bulk DML (tidb_dml_type = "bulk") is a new DML type for handling large batch DML tasks more efficiently while providing transaction guarantees and mitigating OOM issues. This feature differs from import, load, and restore operations when used for data loading.
Enhance the stability of caching the schema information when there is a massive number of tables (experimental, introduced in v8.0.0)SaaS companies using TiDB as the system of record for their multi-tenant applications often need to store a substantial number of tables. In previous versions, handling table counts in the order of a million or more was feasible, but it had the potential to degrade the overall user experience. TiDB v8.0.0 improves the situation by implementing a priority queue for auto analyze, making the process less rigid and enhancing stability across a wider array of tables.
Reliability and availabilityGlobal Sort (GA in v8.0.0)The Global Sort feature aims to improve the stability and efficiency of IMPORT INTO and CREATE INDEX. By globally sorting the data to be processed, this feature improves the stability, controllability, and scalability of data writing to TiKV, consequently enhancing the user experience and service quality of data import and index creation. With global sorting enabled, each IMPORT INTO or CREATE INDEX statement now supports importing or adding indexes for up to 40 TiB of data.
Cross-database SQL binding (introduced in v7.6.0)When managing hundreds of databases with the same schema, it is often necessary to apply SQL bindings across these databases. For example, in SaaS or PaaS data platforms, each user typically operates separate databases with the same schema and runs similar SQL queries on them. In this case, it is impractical to bind SQL for each database one by one. TiDB v7.6.0 introduces cross-database SQL bindings that enable matching bindings across all schema-equivalent databases.
Support TiProxy (GA in v8.0.0)Full support for the TiProxy service, easily deployable via deployment tooling, to manage and maintain connections to TiDB so that they live through rolling restarts, upgrades, or scaling events.
Data Migration (DM) officially supports MySQL 8.0 (GA in v7.6.0)Previously, using DM to migrate data from MySQL 8.0 is an experimental feature and is not available for production environments. TiDB v7.6.0 enhances the stability and compatibility of this feature to help you smoothly and quickly migrate data from MySQL 8.0 to TiDB in production environments. In v7.6.0, this feature becomes generally available (GA).
TiDB resource control supports managing queries that consume more resources than expected (GA in v8.1.0)Through the rules of resource groups, TiDB can automatically identify queries that consume more resources than expected, and then limit or cancel these queries. Even if the queries are not identified by the rules, you can still manually add query characteristics and take corresponding measures to reduce the impact of the sudden query performance problem on the entire database.
DB Operations and ObservabilitySupport monitoring index usage statistics (introduced in v8.0.0)Proper index design is a crucial prerequisite to maintaining database performance. TiDB v8.0.0 introduces the INFORMATION_SCHEMA.TIDB_INDEX_USAGE table and the sys.schema_unused_indexes view to provide usage statistics of indexes. This feature helps you assess the efficiency of indexes in the database and optimize the index design.
Data MigrationTiCDC supports the Simple protocol (introduced in v8.0.0)TiCDC introduces a new protocol, the Simple protocol. This protocol provides in-band schema tracking capabilities by embedding table schema information in DDL and BOOTSTRAP events.
TiCDC supports the Debezium format protocol (introduced in v8.0.0)TiCDC introduces a new protocol, the Debezium protocol. TiCDC can now publish data change events to a Kafka sink using a protocol that generates Debezium style messages.
TiCDC supports client authentication (introduced in v8.1.0)TiCDC supports client authentication using mutual Transport Layer Security (mTLS) or TiDB username and password. This feature enables CLI or OpenAPI clients to authenticate their connections to TiCDC.
+ +## Feature details + +### Reliability + +* Support managing queries that consume more resources than expected (GA) [#43691](https://github.com/pingcap/tidb/issues/43691) @[nolouch](https://github.com/nolouch) + + Sudden SQL query performance problems can cause a decline in overall database performance, which is the most common challenge to database stability. The reasons for these problems are diverse, such as untested new SQL statements, drastic changes in data volume, and sudden changes in execution plans. These problems are difficult to avoid completely at the source. TiDB v7.2.0 has introduced the capability to manage queries that consume more resources than expected to quickly reduce the impact of sudden query performance problems. This feature becomes generally available in v8.1.0. + + You can set the maximum execution time for a query in a resource group. When the execution time of a query exceeds the set value, the priority of the query is automatically reduced or the query is canceled. You can also set immediately matching identified queries through text or execution plans within a period of time, to avoid excessive resource consumption during the identification phase when the concurrency of problematic queries is too high. + + TiDB also supports the manual marking of queries. By using the [`QUERY WATCH`](/sql-statements/sql-statement-query-watch.md) command, you can mark queries based on the SQL text, SQL Digest, or execution plan. The queries that match the mark can be downgraded or canceled, achieving the purpose of adding a SQL blocklist. + + The automatic management capability of queries that consume more resources than expected provides users with an effective means to quickly mitigate the impact of query problems on overall performance before the root cause is identified, thereby improving the stability of the database. + + For more information, see [documentation](/tidb-resource-control.md#manage-queries-that-consume-more-resources-than-expected-runaway-queries). + +### SQL + +* Support using more expressions to set default column values when creating a table (GA) [#50936](https://github.com/pingcap/tidb/issues/50936) @[zimulala](https://github.com/zimulala) + + Before v8.0.0, when you create a table, the default value of a column is limited to strings, numbers, dates, and certain expressions. Starting from v8.0.0, you can use more expressions as the default column values. For example, you can set the default value of a column to `DATE_FORMAT`. This feature helps you meet more diverse requirements. In v8.1.0, this feature becomes GA. + + Starting from v8.1.0, you can use expressions as default values when adding columns by `ADD COLUMN`. + + For more information, see [documentation](/data-type-default-values.md#specify-expressions-as-default-values). + +### DB operations + +* Enable the TiDB Distributed eXecution Framework (DXF) by default to enhance the performance and stability of `ADD INDEX` or `IMPORT INTO` tasks in parallel execution [#52441](https://github.com/pingcap/tidb/issues/52441) @[D3Hunter](https://github.com/D3Hunter) + + The DXF becomes generally available (GA) in v7.5.0, but it is disabled by default. This means that an `ADD INDEX` or `IMPORT INTO` task is executed only by one TiDB node by default. + + Starting from v8.1.0, TiDB enables this feature by default ([`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710) defaults to `ON`). When enabled, the DXF can schedule multiple TiDB nodes to execute the same `ADD INDEX` or `IMPORT INTO` task in parallel, fully utilizing the resources of the TiDB cluster and greatly improving the performance of these tasks. In addition, you can linearly improve the performance of `ADD INDEX` and `IMPORT INTO` tasks by adding TiDB nodes and configuring [`tidb_service_scope`](/system-variables.md#tidb_service_scope-new-in-v740) for the newly added nodes. + + For more information, see [documentation](/tidb-distributed-execution-framework.md). + +### Security + +* Enhance TiDB log desensitization (GA) [#52364](https://github.com/pingcap/tidb/issues/52364) @[xhebox](https://github.com/xhebox) + + The enhanced TiDB log desensitization supports removing sensitive data when users view logs, implemented by marking SQL text information in log files. You can control whether to mark log information to enable secure use of TiDB logs in different scenarios, enhancing the security and flexibility of using log desensitization. To use this feature, set the system variable `tidb_redact_log` to `MARKER`, and then the SQL text in TiDB's runtime logs is marked. In addition, you can use the `collect-log` subcommand on the TiDB server to remove marked sensitive data from the logs and display the logs in a secure manner. You can also remove all markers and get the normal logs. This feature became generally available in v8.1.0. + + For more information, see [documentation](/system-variables.md#tidb_redact_log). + +### Data migration + +* Support the `IMPORT INTO ... FROM SELECT` syntax (GA) [#49883](https://github.com/pingcap/tidb/issues/49883) @[D3Hunter](https://github.com/D3Hunter) + + Before v8.0.0, importing query results into a target table could only be done using the `INSERT INTO ... SELECT` statement, which is relatively inefficient in some large dataset scenarios. In v8.0.0, TiDB introduces `IMPORT INTO ... FROM SELECT` as an experimental feature, which enables you to import the results of a `SELECT` query into an empty TiDB target table. It achieves up to 8 times the performance of `INSERT INTO ... SELECT` and significantly reduces the import time. In addition, you can use `IMPORT INTO ... FROM SELECT` to import historical data queried with [`AS OF TIMESTAMP`](/as-of-timestamp.md). + + In v8.1.0, the `IMPORT INTO ... FROM SELECT` syntax becomes generally available (GA), enriching the functionality scenarios of the `IMPORT INTO` statement. + + For more information, see [documentation](/sql-statements/sql-statement-import-into.md). + +* TiDB Lightning simplifies conflict resolution strategies and supports handling conflicting data using the `replace` strategy (GA) [#51036](https://github.com/pingcap/tidb/issues/51036) @[lyzx2001](https://github.com/lyzx2001) + + Before v8.0.0, TiDB Lightning has [one data conflict resolution strategy](/tidb-lightning/tidb-lightning-logical-import-mode-usage.md#conflict-detection) for the logical import mode and [two data conflict resolution strategies](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#conflict-detection) for the physical import mode, which are not easy to understand and configure. + + In v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md) parameter (experimental), and simplifies the configuration of this parameter. In addition, in the physical import mode, the `replace` strategy supports retaining the latest data and overwriting the old data when the import detects data with primary key or unique key conflicts. In v8.1.0, the capability to handle conflicting data with the `replace` strategy becomes generally available (GA). + + For more information, see [documentation](/tidb-lightning/tidb-lightning-configuration.md). + +* TiCDC supports client authentication [#10636](https://github.com/pingcap/tiflow/issues/10636) @[CharlesCheung96](https://github.com/CharlesCheung96) + + In v8.1.0, TiCDC supports client authentication when you are using the TiCDC CLI or OpenAPI. This feature enables you to configure TiCDC to require client authentication using client certificates, thereby establishing mutual Transport Layer Security (mTLS). Additionally, you can configure authentication based on TiDB username and password. + + For more information, see [documentation](/ticdc/ticdc-client-authentication.md). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v8.0.0 to the current version (v8.1.0). If you are upgrading from v7.6.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### Behavior changes + +* In earlier versions, the `tidb.tls` configuration item in TiDB Lightning treats values `"false"` and `""` the same, as well as treating the values `"preferred"` and `"skip-verify"` the same. Starting from v8.1.0, TiDB Lightning distinguishes the behavior of `"false"`, `""`, `"skip-verify"`, and `"preferred"` for `tidb.tls`. For more information, see [TiDB Lightning configuration](/tidb-lightning/tidb-lightning-configuration.md). +* For tables with `AUTO_ID_CACHE=1`, TiDB supports a [centralized auto-increment ID allocating service](/auto-increment.md#mysql-compatibility-mode). In earlier versions, the primary TiDB node of this service automatically performs a `forceRebase` operation when the TiDB process exits (for example, during the TiDB node restart) to keep auto-assigned IDs as consecutive as possible. However, when there are too many tables with `AUTO_ID_CACHE=1`, executing `forceRebase` becomes very time-consuming, preventing TiDB from restarting promptly and even blocking data writes, thus affecting system availability. To resolve this issue, starting from v8.1.0, TiDB removes the `forceRebase` behavior, but this change will cause some auto-assigned IDs to be non-consecutive during the failover. +* In earlier versions, when processing a transaction containing `UPDATE` changes, if the primary key or non-null unique index value is modified in an `UPDATE` event, TiCDC splits this event into `DELETE` and `INSERT` events. In v8.1.0, when using the MySQL sink, TiCDC splits an `UPDATE` event into `DELETE` and `INSERT` events if the transaction `commitTS` for the `UPDATE` change is less than TiCDC `thresholdTS` (which is the current timestamp that TiCDC fetches from PD at TiCDC startup). This behavior change addresses the issue of downstream data inconsistencies caused by the potentially incorrect order of `UPDATE` events received by TiCDC, which can lead to an incorrect order of split `DELETE` and `INSERT` events. For more information, see [documentation](/ticdc/ticdc-split-update-behavior.md#split-update-events-for-mysql-sinks). + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_auto_analyze_ratio`](/system-variables.md#tidb_auto_analyze_ratio) | Modified | Changes the value range from `[0, 18446744073709551615]` to `(0, 1]`. | +| [`tidb_enable_dist_task`](/system-variables.md#tidb_enable_dist_task-new-in-v710) | Modified | Changes the default value from `OFF` to `ON`. This means that Distributed eXecution Framework (DXF) is enabled by default, which fully utilizes the resources of the TiDB cluster and greatly improves the performance of `ADD INDEX` and `IMPORT INTO` tasks. If you want to upgrade a cluster with the DXF enabled to v8.1.0 or later, disable the DXF (by setting `tidb_enable_dist_task` to `OFF`) before the upgrade, which avoids `ADD INDEX` operations during the upgrade causing data index inconsistency. After the upgrade, you can manually enable the DXF. | +| [`tidb_service_scope`](/system-variables.md#tidb_service_scope-new-in-v740) | Modified | Changes the optional value from `""` or `background` to a string with a length of up to 64 characters, which enables you to control the service scope of each TiDB node more flexibly. Valid characters include digits `0-9`, letters `a-zA-Z`, underscores `_`, and hyphens `-`. The Distributed eXecution Framework (DXF) determines which TiDB nodes can be scheduled to execute distributed tasks based on the value of this variable. For specific rules, see [Task scheduling](/tidb-distributed-execution-framework.md#task-scheduling). | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB| [`concurrently-init-stats`](/tidb-configuration-file.md#concurrently-init-stats-new-in-v810-and-v752) | Newly added | Controls whether to initialize statistics concurrently during TiDB startup. The default value is `false`. | +| TiDB Lightning | [`conflict.max-record-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-configuration) | Modified | Starting from v8.1.0, there is no need to configure `conflict.max-record-rows` manually, because TiDB Lightning automatically assigns the value of `conflict.max-record-rows` with the value of `conflict.threshold`, regardless of the user input. `conflict.max-record-rows` will be deprecated in a future release. | +| TiDB Lightning | [`conflict.threshold`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) | Modified | Changes the default value from `9223372036854775807` to `10000` to quickly interrupt abnormal tasks so that you can make corresponding adjustments as soon as possible. This saves time and computational resources by avoiding the scenario where a large amount of conflicting data is discovered after the import, caused by abnormal data sources or incorrect table schema definitions. | +| TiCDC | [`security.client-allowed-user`](/ticdc/ticdc-server-config.md#cdc-server-configuration-file-parameters) | Newly added | Lists the usernames that are allowed for client authentication. Authentication requests with usernames not in this list will be rejected. The default value is null. | +| TiCDC | [`security.client-user-required`](/ticdc/ticdc-server-config.md#cdc-server-configuration-file-parameters) | Newly added | Controls whether to use username and password for client authentication. The default value is `false`. | +| TiCDC | [`security.mtls`](/ticdc/ticdc-server-config.md#cdc-server-configuration-file-parameters) | Newly added | Controls whether to enable the TLS client authentication. The default value is `false`. | +| TiCDC | [`sink.debezium.output-old-value`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | Controls whether to output the value before the row data changes. The default value is `true`. When it is disabled, the `UPDATE` event does not output the "before" field. | +| TiCDC | [`sink.open.output-old-value`](/ticdc/ticdc-changefeed-config.md#changefeed-configuration-parameters) | Newly added | Controls whether to output the value before the row data changes. The default value is `true`. When it is disabled, the `UPDATE` event does not output the "p" field. | + +## Deprecated features + +* It is planned to redesign [the auto-evolution of execution plan bindings](/sql-plan-management.md#baseline-evolution) in subsequent releases, and the related variables and behavior will change. +* The TiDB Lightning parameter [`conflict.max-record-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) is scheduled for deprecation in a future release and will be subsequently removed. This parameter will be replaced by `conflict.threshold`, which means that the maximum number of conflicting records is consistent with the maximum number of conflicting records that can be tolerated in a single import task. +* Starting from v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, and enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md) parameter. The [`duplicate-resolution`](/tidb-lightning/tidb-lightning-configuration.md) parameter for the old version of conflict detection will be removed in a future release. + +## Improvements + ++ TiDB + + - Improve the MySQL compatibility of foreign keys displayed in the output of `SHOW CREATE TABLE` [#51837](https://github.com/pingcap/tidb/issues/51837) @[negachov](https://github.com/negachov) + - Improve the MySQL compatibility of expression default values displayed in the output of `SHOW CREATE TABLE` [#52939](https://github.com/pingcap/tidb/issues/52939) @[CbcWestwolf](https://github.com/CbcWestwolf) + - Support adding multiple indexes concurrently in the ingest mode [#52596](https://github.com/pingcap/tidb/issues/52596) @[lance6716](https://github.com/lance6716) + - Support configuring the system variable `tidb_service_scope` with various values, enhancing the utilization of the Distributed eXecution Framework (DXF) [#52441](https://github.com/pingcap/tidb/issues/52441) @[ywqzzy](https://github.com/ywqzzy) + - Enhance the handling of DNF items that are always `false` by directly ignoring such filter conditions, thus avoiding unnecessary full table scans [#40997](https://github.com/pingcap/tidb/issues/40997) @[hi-rustin](https://github.com/Rustin170506) + - Support using Optimizer Fix Controls to remove the limitation that the optimizer does not automatically choose Index Merge for a query when the optimizer can choose the single index scan method (other than full table scan) for the query [#52869](https://github.com/pingcap/tidb/issues/52869) @[time-and-fate](https://github.com/time-and-fate) + - Add the `total_kv_read_wall_time` metric to the column `execution info` of Coprocessor operators [#28937](https://github.com/pingcap/tidb/issues/28937) @[cfzjywxk](https://github.com/cfzjywxk) + - Add the `RU (max)` metric on the Resource Control dashboard [#49318](https://github.com/pingcap/tidb/issues/49318) @[nolouch](https://github.com/nolouch) + - Add a timeout mechanism for LDAP authentication to avoid the issue of resource lock (RLock) not being released in time [#51883](https://github.com/pingcap/tidb/issues/51883) @[YangKeao](https://github.com/YangKeao) + ++ TiKV + + - Avoid performing IO operations on snapshot files in Raftstore threads to improve TiKV stability [#16564](https://github.com/tikv/tikv/issues/16564) @[Connor1996](https://github.com/Connor1996) + - Accelerate the shutdown speed of TiKV [#16680](https://github.com/tikv/tikv/issues/16680) @[LykxSassinator](https://github.com/LykxSassinator) + - Add metrics for memory usage per thread [#15927](https://github.com/tikv/tikv/issues/15927) @[Connor1996](https://github.com/Connor1996) + ++ PD + + - Optimize the logic for `OperatorController` to reduce the overhead of competition locks [#7897](https://github.com/tikv/pd/issues/7897) @[nolouch](https://github.com/nolouch) + ++ TiFlash + + - Mitigate the issue that TiFlash might panic due to updating certificates after TLS is enabled [#8535](https://github.com/pingcap/tiflash/issues/8535) @[windtalker](https://github.com/windtalker) + ++ Tools + + + Backup & Restore (BR) + + - Add PITR integration test cases to cover compatibility testing for log backup and adding index acceleration [#51987](https://github.com/pingcap/tidb/issues/51987) @[Leavrth](https://github.com/Leavrth) + - Remove the invalid verification for active DDL jobs when log backup starts [#52733](https://github.com/pingcap/tidb/issues/52733) @[Leavrth](https://github.com/Leavrth) + - Add test cases to test compatibility between PITR and the acceleration of adding indexes feature [#51988](https://github.com/pingcap/tidb/issues/51988) @[Leavrth](https://github.com/Leavrth) + - BR cleans up empty SST files during data recovery [#16005](https://github.com/tikv/tikv/issues/16005) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Improve memory stability during data recovery using redo logs to reduce the probability of OOM [#10900](https://github.com/pingcap/tiflow/issues/10900) @[CharlesCheung96](https://github.com/CharlesCheung96) + - Significantly improve the stability of data replication in transaction conflict scenarios, with up to 10 times performance improvement [#10896](https://github.com/pingcap/tiflow/issues/10896) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Bug fixes + ++ TiDB + + - Fix the issue that executing SQL statements containing tables with multi-valued indexes might return the `Can't find a proper physical plan for this query` error [#49438](https://github.com/pingcap/tidb/issues/49438) @[qw4990](https://github.com/qw4990) + - Fix the issue that automatic statistics collection gets stuck after an OOM error occurs [#51993](https://github.com/pingcap/tidb/issues/51993) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that after using BR to restore a table that has no statistics, the statistics health of that table is still 100% [#29769](https://github.com/pingcap/tidb/issues/29769) @[winoros](https://github.com/winoros) + - Fix the issue that TiDB creates statistics for system tables during upgrade [#52040](https://github.com/pingcap/tidb/issues/52040) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that automatic statistics collection is triggered before the initialization of statistics finishes [#52346](https://github.com/pingcap/tidb/issues/52346) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiDB might crash when `tidb_mem_quota_analyze` is enabled and the memory used by updating statistics exceeds the limit [#52601](https://github.com/pingcap/tidb/issues/52601) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the TiDB synchronously loading statistics mechanism retries to load empty statistics indefinitely and prints the `fail to get stats version for this histogram` log [#52657](https://github.com/pingcap/tidb/issues/52657) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that expressions containing different collations might cause the query to panic when the new framework for collations is disabled [#52772](https://github.com/pingcap/tidb/issues/52772) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the `CPS by type` metric displays incorrect values [#52605](https://github.com/pingcap/tidb/issues/52605) @[nolouch](https://github.com/nolouch) + - Fix the issue that the nil pointer error occurs when you query `INFORMATION_SCHEMA.TIKV_REGION_STATUS` [#52013](https://github.com/pingcap/tidb/issues/52013) @[JmPotato](https://github.com/JmPotato) + - Fix the incorrect error message displayed when an invalid default value is specified for a column [#51592](https://github.com/pingcap/tidb/issues/51592) @[danqixu](https://github.com/danqixu) + - Fix the issue that adding indexes in the ingest mode might cause inconsistent data index in some corner cases [#51954](https://github.com/pingcap/tidb/issues/51954) @[lance6716](https://github.com/lance6716) + - Fix the issue that DDL operations get stuck when restoring a table with the foreign key [#51838](https://github.com/pingcap/tidb/issues/51838) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that adding indexes fails when the TiDB network is isolated [#51846](https://github.com/pingcap/tidb/issues/51846) @[ywqzzy](https://github.com/ywqzzy) + - Fix the issue that adding an index with the same name after renaming an index causes an error [#51431](https://github.com/pingcap/tidb/issues/51431) @[lance6716](https://github.com/lance6716) + - Fix the issue of inconsistent data indexes caused by cluster upgrade during adding indexes [#52411](https://github.com/pingcap/tidb/issues/52411) @[tangenta](https://github.com/tangenta) + - Fix the issue that adding indexes to large tables fails after enabling the Distributed eXecution Framework (DXF) [#52640](https://github.com/pingcap/tidb/issues/52640) @[tangenta](https://github.com/tangenta) + - Fix the issue that adding indexes concurrently reports the error `no such file or directory` [#52475](https://github.com/pingcap/tidb/issues/52475) @[tangenta](https://github.com/tangenta) + - Fix the issue that the temporary data cannot be cleaned up after adding indexes fails [#52639](https://github.com/pingcap/tidb/issues/52639) @[lance6716](https://github.com/lance6716) + - Fix the issue that the metadata lock fails to prevent DDL operations from executing in the plan cache scenario [#51407](https://github.com/pingcap/tidb/issues/51407) @[wjhuang2016](https://github.com/wjhuang2016) + - Fix the issue that the `IMPORT INTO` operation gets stuck when importing a large amount of data [#52884](https://github.com/pingcap/tidb/issues/52884) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB unexpectedly restarts when logging gRPC errors [#51301](https://github.com/pingcap/tidb/issues/51301) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that IndexHashJoin outputs redundant data when calculating Anti Left Outer Semi Join [#52923](https://github.com/pingcap/tidb/issues/52923) @[yibin87](https://github.com/yibin87) + - Fix the incorrect result of the TopN operator in correlated subqueries [#52777](https://github.com/pingcap/tidb/issues/52777) @[yibin87](https://github.com/yibin87) + - Fix the inaccurate execution time statistics of HashJoin probe [#52222](https://github.com/pingcap/tidb/issues/52222) @[windtalker](https://github.com/windtalker) + - Fix the issue that using `TABLESAMPLE` returns incorrect results in static partition pruning mode (`tidb_partition_prune_mode='static'`) [#52282](https://github.com/pingcap/tidb/issues/52282) @[tangenta](https://github.com/tangenta) + - Fix the issue that TTL is deviated by 1 hour in daylight saving time [#51675](https://github.com/pingcap/tidb/issues/51675) @[lcwangchao](https://github.com/lcwangchao) + - Fix the incorrect calculation and display of the number of connections (Connection Count) on the TiDB Dashboard Monitoring page [#51889](https://github.com/pingcap/tidb/issues/51889) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the status gets stuck when rolling back the partition DDL tasks [#51090](https://github.com/pingcap/tidb/issues/51090) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the value of `max_remote_stream` is incorrect when executing `EXPLAIN ANALYZE` [#52646](https://github.com/pingcap/tidb/issues/52646) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that querying the `TIDB_HOT_REGIONS` table might incorrectly return `INFORMATION_SCHEMA` tables [#50810](https://github.com/pingcap/tidb/issues/50810) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the `EXPLAIN` statement might display incorrect column IDs in the result when statistics for certain columns are not fully loaded [#52207](https://github.com/pingcap/tidb/issues/52207) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that the type returned by the `IFNULL` function is inconsistent with MySQL [#51765](https://github.com/pingcap/tidb/issues/51765) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that adding a unique index might cause TiDB to panic [#52312](https://github.com/pingcap/tidb/issues/52312) @[wjhuang2016](https://github.com/wjhuang2016) + ++ TiKV + + - Fix the issue that resolve-ts is blocked when a stale Region peer ignores the GC message [#16504](https://github.com/tikv/tikv/issues/16504) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that inactive Write Ahead Logs (WALs) in RocksDB might corrupt data [#16705](https://github.com/tikv/tikv/issues/16705) @[Connor1996](https://github.com/Connor1996) + ++ PD + + - Fix the issue that TSO might get stuck when toggling the PD microservice mode on and off [#7849](https://github.com/tikv/pd/issues/7849) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the `State` monitoring metric for DR Auto-Sync does not show any data [#7974](https://github.com/tikv/pd/issues/7974) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that checking binary versions might cause PD panic [#7978](https://github.com/tikv/pd/issues/7978) @[JmPotato](https://github.com/JmPotato) + - Fix the type conversion error that occurs when TTL parameters are parsed [#7980](https://github.com/tikv/pd/issues/7980) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the Leader fails to transfer when you switch it between two deployed data centers [#7992](https://github.com/tikv/pd/issues/7992) @[TonsnakeLin](https://github.com/TonsnakeLin) + - Fix the issue that `PrintErrln` in pd-ctl fails to output error messages to `stderr` [#8022](https://github.com/tikv/pd/issues/8022) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that PD might panic when generating `Merge` schedules [#8049](https://github.com/tikv/pd/issues/8049) @[nolouch](https://github.com/nolouch) + - Fix the panic issue caused by `GetAdditionalInfo` [#8079](https://github.com/tikv/pd/issues/8079) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the `Filter target` monitoring metric for PD does not provide scatter range information [#8125](https://github.com/tikv/pd/issues/8125) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the query result of `SHOW CONFIG` includes the deprecated configuration item `trace-region-flow` [#7917](https://github.com/tikv/pd/issues/7917) @[rleungx](https://github.com/rleungx) + - Fix the issue that the scaling progress is not correctly displayed [#7726](https://github.com/tikv/pd/issues/7726) @[CabinfeverB](https://github.com/CabinfeverB) + ++ TiFlash + + - Fix the issue that TiFlash might panic when you insert data to columns with invalid default values in non-strict `sql_mode` [#8803](https://github.com/pingcap/tiflash/issues/8803) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that TiFlash might return transiently incorrect results in high-concurrency read scenarios [#8845](https://github.com/pingcap/tiflash/issues/8845) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that in the disaggregated storage and compute architecture, the disk `used_size` metric displayed in Grafana is incorrect after you modify the value of the `storage.remote.cache.capacity` configuration item for TiFlash compute nodes [#8920](https://github.com/pingcap/tiflash/issues/8920) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that TiFlash metadata might become corrupted and cause the process to panic when upgrading a cluster from a version earlier than v6.5.0 to v6.5.0 or later [#9039](https://github.com/pingcap/tiflash/issues/9039) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that in the disaggregated storage and compute architecture, TiFlash might panic when the compute node process is stopped [#8860](https://github.com/pingcap/tiflash/issues/8860) @[guo-shaoge](https://github.com/guo-shaoge) + - Fix the issue that TiFlash might return an error when executing queries containing virtual generated columns [#8787](https://github.com/pingcap/tiflash/issues/8787) @[guo-shaoge](https://github.com/guo-shaoge) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that BR cannot back up the `AUTO_RANDOM` ID allocation progress in a union clustered index that contains an `AUTO_RANDOM` column [#52255](https://github.com/pingcap/tidb/issues/52255) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that removing a log backup task after it is paused does not immediately restore the GC safepoint [#52082](https://github.com/pingcap/tidb/issues/52082) @[3pointer](https://github.com/3pointer) + - Fix a rare issue that special event timing might cause the data loss in log backup [#16739](https://github.com/tikv/tikv/issues/16739) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the global checkpoint of log backup is advanced ahead of the actual backup file write point due to TiKV restart, which might cause a small amount of backup data loss [#16809](https://github.com/tikv/tikv/issues/16809) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that the confusing information related to `--concurrency` appears in the log during a full backup [#50837](https://github.com/pingcap/tidb/issues/50837) @[BornChanger](https://github.com/BornChanger) + - Fix the issue that the Region fetched from PD does not have a Leader when restoring data using BR or importing data using TiDB Lightning in physical import mode [#51124](https://github.com/pingcap/tidb/issues/51124) [#50501](https://github.com/pingcap/tidb/issues/50501) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that after pausing, stopping, and rebuilding the log backup task, the task status is normal, but the checkpoint does not advance [#53047](https://github.com/pingcap/tidb/issues/53047) @[RidRisR](https://github.com/RidRisR) + - Fix the unstable test case `TestClearCache` [#51671](https://github.com/pingcap/tidb/issues/51671) @[zxc111](https://github.com/zxc111) + - Fix the unstable test case `TestGetMergeRegionSizeAndCount` [#52095](https://github.com/pingcap/tidb/issues/52095) @[3pointer](https://github.com/3pointer) + - Fix the unstable integration test `br_tikv_outage` [#52673](https://github.com/pingcap/tidb/issues/52673) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the test case `TestGetTSWithRetry` takes too long to execute [#52547](https://github.com/pingcap/tidb/issues/52547) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that TiKV might panic when resuming a paused log backup task with unstable network connections to PD [#17020](https://github.com/tikv/tikv/issues/17020) @[YuJuncen](https://github.com/YuJuncen) + + + TiCDC + + - Fix the issue that calling the API (`/api/v2/owner/resign`) that evicts the TiCDC owner node causes the TiCDC task to restart unexpectedly [#10781](https://github.com/pingcap/tiflow/issues/10781) @[sdojjy](https://github.com/sdojjy) + - Fix the issue that when the downstream Pulsar is stopped, removing the changefeed causes the normal TiCDC process to get stuck, which causes other changefeed processes to get stuck [#10629](https://github.com/pingcap/tiflow/issues/10629) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the **Ownership history** panel in Grafana is unstable [#10796](https://github.com/pingcap/tiflow/issues/10796) @[hongyunyan](https://github.com/hongyunyan) + - Fix the issue that restarting PD might cause the TiCDC node to restart with an error [#10799](https://github.com/pingcap/tiflow/issues/10799) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that high latency in the PD disk I/O causes severe latency in data replication [#9054](https://github.com/pingcap/tiflow/issues/9054) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that the default value of `TIMEZONE` type is not set according to the correct time zone [#10931](https://github.com/pingcap/tiflow/issues/10931) @[3AceShowHand](https://github.com/3AceShowHand) + - Fix the issue that `DROP PRIMARY KEY` and `DROP UNIQUE KEY` statements are not replicated correctly [#10890](https://github.com/pingcap/tiflow/issues/10890) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that TiCDC fails to execute the `Exchange Partition ... With Validation` DDL downstream after it is written upstream, causing the changefeed to get stuck [#10859](https://github.com/pingcap/tiflow/issues/10859) @[hongyunyan](https://github.com/hongyunyan) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning reports `no database selected` during data import due to incompatible SQL statements in the source files [#51800](https://github.com/pingcap/tidb/issues/51800) @[lance6716](https://github.com/lance6716) + - Fix the issue that TiDB Lightning might print sensitive information to logs in server mode [#36374](https://github.com/pingcap/tidb/issues/36374) @[kennytm](https://github.com/kennytm) + - Fix the issue that killing the PD Leader causes TiDB Lightning to report the `invalid store ID 0` error during data import [#50501](https://github.com/pingcap/tidb/issues/50501) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that TiDB Lightning reports the `Unknown column in where clause` error when processing conflicting data using the `replace` strategy [#52886](https://github.com/pingcap/tidb/issues/52886) @[lyzx2001](https://github.com/lyzx2001) + - Fix the issue that TiDB Lightning panics when importing an empty table of Parquet format [#52518](https://github.com/pingcap/tidb/issues/52518) @[kennytm](https://github.com/kennytm) + +## Performance test + +To learn about the performance of TiDB v8.1.0, you can refer to the [TPC-C performance test report](https://docs.pingcap.com/tidbcloud/v8.1-performance-benchmarking-with-tpcc) and [Sysbench performance test report](https://docs.pingcap.com/tidbcloud/v8.1-performance-benchmarking-with-sysbench) of the TiDB Dedicated cluster. + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [arturmelanchyk](https://github.com/arturmelanchyk) (First-time contributor) +- [CabinfeverB](https://github.com/CabinfeverB) +- [danqixu](https://github.com/danqixu) (First-time contributor) +- [imalasong](https://github.com/imalasong) (First-time contributor) +- [jiyfhust](https://github.com/jiyfhust) +- [negachov](https://github.com/negachov) (First-time contributor) +- [testwill](https://github.com/testwill) +- [yzhan1](https://github.com/yzhan1) (First-time contributor) +- [zxc111](https://github.com/zxc111) (First-time contributor) diff --git a/releases/release-8.2.0.md b/releases/release-8.2.0.md new file mode 100644 index 0000000000000..8edc83fea24d9 --- /dev/null +++ b/releases/release-8.2.0.md @@ -0,0 +1,410 @@ +--- +title: TiDB 8.2.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 8.2.0. +--- + +# TiDB 8.2.0 Release Notes + +Release date: July 11, 2024 + +TiDB version: 8.2.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v8.2/quick-start-with-tidb) + +8.2.0 introduces the following key features and improvements: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeature/EnhancementDescription
Reliability and AvailabilityTiProxy supports multiple load balancing policiesIn TiDB v8.2.0, TiProxy evaluates and ranks TiDB nodes based on various dimensions, such as status, connection counts, health, memory, CPU, and location. According to the load balancing policy specified in the policy configuration item, TiProxy dynamically selects the optimal TiDB node to execute database operations. This optimizes overall resource usage, improves cluster performance, and increases throughput.
The parallel HashAgg algorithm of TiDB supports disk spill (GA)HashAgg is a widely used aggregation operator in TiDB for efficiently aggregating rows with the same field values. TiDB v8.0.0 introduces parallel HashAgg as an experimental feature to further enhance processing speed. When memory resources are insufficient, parallel HashAgg spills temporary sorted data to disk, avoiding potential OOM risks caused by excessive memory usage. This improves query performance while maintaining node stability. In v8.2.0, this feature becomes generally available (GA) and is enabled by default, enabling you to safely configure the concurrency of parallel HashAgg using tidb_executor_concurrency.
Improve statistics loading efficiency by up to 10 timesFor clusters with a large number of tables and partitions, such as SaaS or PaaS services, improvement in statistics loading efficiency can solve the problem of slow startup of TiDB instances, and increase the success rate of dynamic loading of statistics. This improvement reduces performance rollbacks caused by statistics loading failures and improves cluster stability.
DB Operations and ObservabilityIntroduce privilege control of switching resource groupsAs resource control is widely used, the privilege control of switching resource groups can prevent database users from abusing resources, strengthen administrators' protection of overall resource usage, and improve cluster stability.
+ +## Feature details + +### Performance + +* Support pushing down the following JSON functions to TiKV [#50601](https://github.com/pingcap/tidb/issues/50601) @[dbsid](https://github.com/dbsid) + + * `JSON_ARRAY_APPEND()` + * `JSON_MERGE_PATCH()` + * `JSON_REPLACE()` + + For more information, see [documentation](/functions-and-operators/expressions-pushed-down.md). + +* TiDB supports parallel sorting [#49217](https://github.com/pingcap/tidb/issues/49217) [#50746](https://github.com/pingcap/tidb/issues/50746) @[xzhangxian1008](https://github.com/xzhangxian1008) + + Before v8.2.0, TiDB only executes Sort operators sequentially, affecting query performance when sorting large amounts of data. + + Starting from v8.2.0, TiDB supports parallel sorting, which significantly improves sorting performance. This feature does not need manual configuration. TiDB automatically determines whether to use parallel sorting based on the value of the [`tidb_executor_concurrency`](/system-variables.md#tidb_executor_concurrency-new-in-v50) system variable. + + For more information, see [documentation](/system-variables.md#tidb_executor_concurrency-new-in-v50). + +* The parallel HashAgg algorithm of TiDB supports disk spill (GA) [#35637](https://github.com/pingcap/tidb/issues/35637) @[xzhangxian1008](https://github.com/xzhangxian1008) + + TiDB v8.0.0 introduces the parallel HashAgg algorithm with disk spill support as an experimental feature. In v8.2.0, this feature becomes generally available (GA). When using the parallel HashAgg algorithm, TiDB automatically triggers data spill based on memory usage, thus balancing query performance and data throughput. This feature is enabled by default. The system variable `tidb_enable_parallel_hashagg_spill`, which controls this feature, will be deprecated in a future release. + + For more information, see [documentation](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800). + +### Reliability + +* Improve statistics loading efficiency by up to 10 times [#52831](https://github.com/pingcap/tidb/issues/52831) @[hawkingrei](https://github.com/hawkingrei) + + SaaS or PaaS applications can have a large number of data tables, which not only slow down the loading speed of the initial statistics, but also increase the failure rate of load synchronization under high loads. The startup time of TiDB and the accuracy of the execution plan can be affected. In v8.2.0, TiDB optimizes the process of loading statistics from multiple perspectives, such as the concurrency model and memory allocation, to reduce latency, improve throughput, and avoid slow loading of statistics that affect business scaling. + + Adaptive concurrent loading is now supported. By default, the configuration item [`stats-load-concurrency`](/tidb-configuration-file.md#stats-load-concurrency-new-in-v540) is set to `0`, and the concurrency of statistics loading is automatically selected based on the hardware specification. + + For more information, see [documentation](/tidb-configuration-file.md#stats-load-concurrency-new-in-v540). + +### Availability + +* TiProxy supports multiple load balancing policies [#465](https://github.com/pingcap/tiproxy/issues/465) @[djshow832](https://github.com/djshow832) @[xhebox](https://github.com/xhebox) + + TiProxy is the official proxy component of TiDB, located between the client and TiDB server. It provides load balancing and connection persistence functions for TiDB. Before v8.2.0, TiProxy defaults to v1.0.0, which only supports status-based and connection count-based load balancing policies for TiDB servers. + + Starting from v8.2.0, TiProxy defaults to v1.1.0 and introduces multiple load balancing policies. In addition to status-based and connection count-based policies, TiProxy supports dynamic load balancing based on health, memory, CPU, and location, improving the stability of the TiDB cluster. + + You can configure the combination and priority of load balancing policies through the [`policy`](/tiproxy/tiproxy-configuration.md#policy) configuration item. + + * `resource`: the resource priority policy performs load balancing based on the following priority order: status, health, memory, CPU, location, and connection count. + * `location`: the location priority policy performs load balancing based on the following priority order: status, location, health, memory, CPU, and connection count. + * `connection`: the minimum connection count priority policy performs load balancing based on the following priority order: status and connection count. + + For more information, see [documentation](/tiproxy/tiproxy-load-balance.md). + +### SQL + +* TiDB supports the JSON schema validation function [#52779](https://github.com/pingcap/tidb/issues/52779) @[dveeden](https://github.com/dveeden) + + Before v8.2.0, you need to rely on external tools or customized validation logic for JSON data validation, which increases the complexity of development and maintenance, and reduces development efficiency. Starting from v8.2.0, the `JSON_SCHEMA_VALID()` function is introduced. Using `JSON_SCHEMA_VALID()` in the `CHECK` constraint can help prevent non-conforming data from being inserted, rather than checking the data after it has been added. This function lets you verify the validity of JSON data directly in TiDB, improving the integrity and consistency of the data, and increasing the development efficiency. + + For more information, see [documentation](/functions-and-operators/json-functions.md#validation-functions). + +### DB operations + +* TiUP supports deploying PD microservices [#5766](https://github.com/tikv/pd/issues/5766) @[rleungx](https://github.com/rleungx) + + Starting from v8.0.0, PD supports the microservice mode. This mode splits the timestamp allocation and cluster scheduling functions of PD into separate microservices that can be deployed independently, thereby improving resource control and isolation, and reducing the impact between different services. Before v8.2.0, PD microservices can only be deployed using TiDB Operator. + + Starting from v8.2.0, PD microservices can also be deployed using TiUP. You can deploy the `tso` microservice and the `scheduling` microservice separately in a cluster to enhance PD performance scalability and address PD performance bottlenecks in large-scale clusters. It is recommended to use this mode when PD becomes a significant performance bottleneck that cannot be resolved by scaling up. + + For more information, see [user documentation](/pd-microservices.md). + +* Add privilege control of switching resource groups [#53440](https://github.com/pingcap/tidb/issues/53440) @[glorv](https://github.com/glorv) + + TiDB lets users switch to other resource groups using the [`SET RESOURCE GROUP`](/sql-statements/sql-statement-set-resource-group.md) command or the [`RESOURCE_GROUP()`](/optimizer-hints.md#resource_groupresource_group_name) hint, which might lead to resource group abuse by some database users. TiDB v8.2.0 introduces privilege control of switching resource groups. Only database users granted the `RESOURCE_GROUP_ADMIN` or `RESOURCE_GROUP_USER` dynamic privilege can switch to other resource groups, enhancing the protection of system resources. + + To maintain compatibility, the original behavior is retained when upgrading from earlier versions to v8.2.0 or later versions. To enable the enhanced privilege control, set the new variable [`tidb_resource_control_strict_mode`](/system-variables.md#tidb_resource_control_strict_mode-new-in-v820) to `ON`. + + For more information, see [user documentation](/tidb-resource-control.md#bind-resource-groups). + +### Observability + +* Record the reason why an execution plan is not cached [#50618](https://github.com/pingcap/tidb/issues/50618) @[qw4990](https://github.com/qw4990) + + In some scenarios, you might want to cache most execution plans to save execution overhead and reduce latency. Currently, execution plan caching has some limitations on SQL. Execution plans of some SQL statements cannot be cached. It is difficult to identify the SQL statements that cannot be cached and the corresponding reasons. + + Therefore, starting from v8.2.0, new columns `PLAN_CACHE_UNQUALIFIED` and `PLAN_CACHE_UNQUALIFIED_LAST_REASON` are added to the system table [`STATEMENTS_SUMMARY`](/statement-summary-tables.md) to explain the reason why an execution plan cannot be cached, which can help you tune performance. + + For more information, see [documentation](/statement-summary-tables.md#fields-description). + +### Security + +* Enhance TiFlash log desensitization [#8977](https://github.com/pingcap/tiflash/issues/8977) @[JaySon-Huang](https://github.com/JaySon-Huang) + + TiDB v8.0.0 enhances the log desensitization feature, enabling you to control whether user data in TiDB logs is wrapped in markers `‹ ›`. Based on the marked logs, you can decide whether to redact the marked information when displaying logs, thereby increasing the flexibility of log desensitization. In v8.2.0, TiFlash introduces a similar enhancement for log desensitization. To use this feature, set the TiFlash configuration item `security.redact_info_log` to `marker`. + + For more information, see [documentation](/tiflash/tiflash-configuration.md#configure-the-tiflashtoml-file). + +### Data migration + +* Align TiCDC Syncpoints across multiple changefeeds [#11212](https://github.com/pingcap/tiflow/issues/11212) @[hongyunyan](https://github.com/hongyunyan) + + Before v8.2.0, aligning TiCDC Syncpoints across multiple changefeeds was challenging. The `startTs` of the changefeed had to be carefully selected when the changefeed was created, so it would align with the Syncpoints of other changefeeds. Starting from v8.2.0, Syncpoints for a changefeed are created as a multiple of the changefeed's `sync-point-interval` configuration. This change lets you align Syncpoints across multiple changefeeds that have the same `sync-point-interval` configuration, simplifying and improving the ability to align multiple downstream clusters. + + For more information, see [documentation](/ticdc/ticdc-upstream-downstream-check.md#notes). + +* TiCDC Pulsar Sink supports using the `pulsar+http` and `pulsar+https` connection protocols [#11336](https://github.com/pingcap/tiflow/issues/11336) @[SandeepPadhi](https://github.com/SandeepPadhi) + + Before v8.2.0, TiCDC Pulsar Sink only supports `pulsar` and `pulsar+ssl` connection protocols. Starting from v8.2.0, TiCDC Pulsar Sink also supports `pulsar+http` and `pulsar+https` protocols for connections. This enhancement improves the flexibility of connecting to Pulsar. + + For more information, see [documentation](/ticdc/ticdc-sink-to-pulsar.md#sink-uri). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v8.1.0 to the current version (v8.2.0). If you are upgrading from v8.0.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### Behavior changes + +* When using TiDB Lightning to import a CSV file, if you set `strict-format = true` to split a large CSV file into multiple small CSV files to improve concurrency and import performance, you need to explicitly specify `terminator`. The values can be `\r`, `\n` or `\r\n`. Failure to specify a line terminator might result in an exception when parsing the CSV file data. [#37338](https://github.com/pingcap/tidb/issues/37338) @[lance6716](https://github.com/lance6716) + +* When using [`IMPORT INTO`](/sql-statements/sql-statement-import-into.md) to import a CSV file, if you specify the `SPLIT_FILE` parameter to split a large CSV file into multiple small CSV files to improve concurrency and import performance, you need to explicitly specify the line terminator `LINES_TERMINATED_BY`. The values can be `\r`, `\n` or `\r\n`. Failure to specify a line terminator might result in an exception when parsing the CSV file data. [#37338](https://github.com/pingcap/tidb/issues/37338) @[lance6716](https://github.com/lance6716) + +* Before BR v8.2.0, performing [BR data restore](/br/backup-and-restore-overview.md) on a cluster with TiCDC replication tasks is not supported. Starting from v8.2.0, BR relaxes the restrictions on data restoration for TiCDC: if the BackupTS (the backup time) of the data to be restored is earlier than the changefeed [`CheckpointTS`](/ticdc/ticdc-architecture.md#checkpointts) (the timestamp that indicates the current replication progress), BR can proceed with the data restore normally. Considering that `BackupTS` is usually much earlier, it can be assumed that in most scenarios, BR supports restoring data for a cluster with TiCDC replication tasks. [#53131](https://github.com/pingcap/tidb/issues/53131) @[YuJuncen](https://github.com/YuJuncen) + +### MySQL compatibility + +* Before v8.2.0, executing the [`CREATE USER`](/sql-statements/sql-statement-create-user.md) statement with the `PASSWORD REQUIRE CURRENT DEFAULT` option returns an error because this option is not supported and cannot be parsed. Starting from v8.2.0, TiDB supports parsing and ignoring this option for compatibility with MySQL. [#53305](https://github.com/pingcap/tidb/issues/53305) @[dveeden](https://github.com/dveeden) + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_analyze_distsql_scan_concurrency`](/system-variables.md#tidb_analyze_distsql_scan_concurrency-new-in-v760) | Modified | Changes the minimum value from `1` to `0`. When you set it to `0`, TiDB adaptively adjusts the concurrency of the `scan` operation when executing the `ANALYZE` operation based on the cluster size.| +| [`tidb_analyze_skip_column_types`](/system-variables.md#tidb_analyze_skip_column_types-new-in-v720) | Modified | Starting from v8.2.0, TiDB does not collect columns of `MEDIUMTEXT` and `LONGTEXT` types by default to avoid potential OOM risks.| +| [`tidb_enable_historical_stats`](/system-variables.md#tidb_enable_historical_stats) | Modified | Changes the default value from `ON` to `OFF`, which turns off historical statistics to avoid potential stability issues.| +| [`tidb_executor_concurrency`](/system-variables.md#tidb_executor_concurrency-new-in-v50) | Modified | Adds support for setting the concurrency of the `sort` operator. | +| [`tidb_sysproc_scan_concurrency`](/system-variables.md#tidb_sysproc_scan_concurrency-new-in-v650) | Modified | Changes the minimum value from `1` to `0`. When you set it to `0`, TiDB adaptively adjusts the concurrency of `scan` operations performed when executing internal SQL statements based on the cluster size.| +| [`tidb_resource_control_strict_mode`](/system-variables.md#tidb_resource_control_strict_mode-new-in-v820) | Newly added | Controls whether privilege control is applied to the [`SET RESOURCE GROUP`](/sql-statements/sql-statement-set-resource-group.md) statement and the [`RESOURCE_GROUP()`](/optimizer-hints.md#resource_groupresource_group_name) optimizer hint.| + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`stats-load-concurrency`](/tidb-configuration-file.md#stats-load-concurrency-new-in-v540) | Modified | Changes the default value from `5` to `0`, and the minimum value from `1` to `0`. The value `0` means the automatic mode, which automatically adjusts concurrency based on the configuration of the server. | +| TiDB | [`token-limit`](/tidb-configuration-file.md#token-limit) | Modified | Changes the maximum value from `18446744073709551615` (64-bit platform) and `4294967295` (32-bit platform) to `1048576` to avoid causing TiDB Server OOM when setting it too large. It means that the number of sessions that can execute requests concurrently can be configured to a maximum of `1048576`. | +| TiKV | [`max-apply-unpersisted-log-limit`](/tikv-configuration-file.md#max-apply-unpersisted-log-limit-new-in-v810) | Modified | Changes the default value from `0` to `1024` to reduce long-tail latency caused by I/O jitter on the TiKV node. It means that the maximum number of committed but not persisted Raft logs that can be applied is `1024` by default. | +| TiKV | [`server.grpc-compression-type`](/tikv-configuration-file.md#grpc-compression-type) | Modified | This configuration item now also controls the compression algorithm of response messages sent from TiKV to TiDB. Enabling compression might consume more CPU resources. | +| TiFlash | [`security.redact_info_log`](/tiflash/tiflash-configuration.md#configure-the-tiflashtoml-file) | Modified | Introduces a new value option `marker`. When you set the value to `marker`, all user data in the log is wrapped in `‹ ›`. | + +### System tables + +* The [`INFORMATION_SCHEMA.PROCESSLIST`](/information-schema/information-schema-processlist.md) and [`INFORMATION_SCHEMA.CLUSTER_PROCESSLIST`](/information-schema/information-schema-processlist.md#cluster_processlist) system tables add the `SESSION_ALIAS` field to show the alias of the current session. [#46889](https://github.com/pingcap/tidb/issues/46889) @[lcwangchao](https://github.com/lcwangchao) + +### Compiler versions + +* To improve the TiFlash development experience, the minimum version of LLVM required to compile and build TiDB has been upgraded from 13.0 to 17.0. If you are a TiDB developer, you need to upgrade the version of your LLVM compiler to ensure a smooth build. [#7193](https://github.com/pingcap/tiflash/issues/7193) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + +## Deprecated features + +* The following features are deprecated starting from v8.2.0: + + * Starting from v8.2.0, the [`enable-replica-selector-v2`](/tidb-configuration-file.md#enable-replica-selector-v2-new-in-v800) configuration item is deprecated. The new version of the Region replica selector is used by default when sending RPC requests to TiKV. + * Starting from v8.2.0, the BR snapshot restore parameter `--concurrency` is deprecated. As an alternative, you can configure the maximum number of concurrent tasks per TiKV node during snapshot restore using [`--tikv-max-restore-concurrency`](/br/use-br-command-line-tool.md#common-options). + * Starting from v8.2.0, the BR snapshot restore parameter `--granularity` is deprecated, and the [coarse-grained Region scattering algorithm](/br/br-snapshot-guide.md#restore-cluster-snapshots) is enabled by default. + +* The following features are planned for deprecation in future versions: + + * In v8.0.0, TiDB introduces the [`tidb_enable_auto_analyze_priority_queue`](/system-variables.md#tidb_enable_auto_analyze_priority_queue-new-in-v800) system variable to control whether to enable the priority queue to optimize the ordering of automatic statistics collection tasks. In future versions, the priority queue will become the only way to order automatic statistics collection tasks, and the [`tidb_enable_auto_analyze_priority_queue`](/system-variables.md#tidb_enable_auto_analyze_priority_queue-new-in-v800) system variable will be deprecated. + * In v8.0.0, TiDB introduces the [`tidb_enable_parallel_hashagg_spill`](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800) system variable to control whether TiDB supports disk spill for the concurrent HashAgg algorithm. In future versions, the [`tidb_enable_parallel_hashagg_spill`](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800) system variable will be deprecated. + * In v7.5.0, TiDB introduces the [`tidb_enable_async_merge_global_stats`](/system-variables.md#tidb_enable_async_merge_global_stats-new-in-v750) system variable to enable TiDB to merge partition statistics asynchronously to avoid OOM issues. In future versions, partition statistics will be merged asynchronously by default, and the [`tidb_enable_async_merge_global_stats`](/system-variables.md#tidb_enable_async_merge_global_stats-new-in-v750) system variable will be deprecated. + * It is planned to redesign [the auto-evolution of execution plan bindings](/sql-plan-management.md#baseline-evolution) in subsequent releases, and the related variables and behavior will change. + * The TiDB Lightning parameter [`conflict.max-record-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) is planned for deprecation in a future release and will be subsequently removed. This parameter will be replaced by [`conflict.threshold`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task), which means that the maximum number of conflicting records is consistent with the maximum number of conflicting records that can be tolerated in a single import task. + +* The following features are planned for removal in future versions: + + * Starting from v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, and enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) parameter. The [`duplicate-resolution`](/tidb-lightning/tidb-lightning-configuration.md) parameter for the old version of conflict detection will be removed in a future release. + +## Improvements + ++ TiDB + + - Support parallel execution of [logical DDL statements (General DDL)](/ddl-introduction.md#types-of-ddl-statements). Compared with v8.1.0, when you use 10 sessions to submit different DDL statements concurrently, the performance is improved by 3 to 6 times [#53246](https://github.com/pingcap/tidb/issues/53246) @[D3Hunter](https://github.com/D3Hunter) + - Improve the logic of matching multi-column indexes using expressions like `((a = 1 and b = 2 and c > 3) or (a = 4 and b = 5 and c > 6)) and d > 3` to produce a more accurate `Range` [#41598](https://github.com/pingcap/tidb/issues/41598) @[ghazalfamilyusa](https://github.com/ghazalfamilyusa) + - Optimize the performance of obtaining data distribution information when performing simple queries on tables with large data volumes [#53850](https://github.com/pingcap/tidb/issues/53850) @[you06](https://github.com/you06) + - The aggregated result set can be used as an inner table for IndexJoin, allowing more complex queries to be matched to IndexJoin, thus improving query efficiency through indexing [#37068](https://github.com/pingcap/tidb/issues/37068) @[elsa0520](https://github.com/elsa0520) + - By batch deleting TiFlash placement rules, improve the processing speed of data GC after performing the `TRUNCATE` or `DROP` operation on partitioned tables [#54068](https://github.com/pingcap/tidb/issues/54068) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Upgrade the version of Azure Identity Libraries and Microsoft Authentication Library to enhance security [#53990](https://github.com/pingcap/tidb/issues/53990) @[hawkingrei](https://github.com/hawkingrei) + - Set the maximum value of `token-limit` to `1048576` to avoid causing TiDB Server OOM when setting it too large [#53312](https://github.com/pingcap/tidb/issues/53312) @[djshow832](https://github.com/djshow832) + - Improve column pruning for MPP execution plans to improve TiFlash MPP execution performance [#52133](https://github.com/pingcap/tidb/issues/52133) @[yibin87](https://github.com/yibin87) + - Optimize the performance overhead of the `IndexLookUp` operator when looking up a table with a large amount of data (>1024 rows) [#53871](https://github.com/pingcap/tidb/issues/53871) @[crazycs520](https://github.com/crazycs520) + - Remove stores without Regions during MPP load balancing [#52313](https://github.com/pingcap/tidb/issues/52313) @[xzhangxian1008](https://github.com/xzhangxian1008) + ++ TiKV + + - Add the **Compaction Job Size(files)** metric to show the number of SST files involved in a single compaction job [#16837](https://github.com/tikv/tikv/issues/16837) @[zhangjinpeng87](https://github.com/zhangjinpeng87) + - Enable the [early apply](/tikv-configuration-file.md#max-apply-unpersisted-log-limit-new-in-v810) feature by default. With this feature enabled, the Raft leader can apply logs after quorum peers have persisted the logs, without waiting for the leader itself to persist the log, reducing the impact of jitter in a few TiKV nodes on write request latency [#16717](https://github.com/tikv/tikv/issues/16717) @[glorv](https://github.com/glorv) + - Improve the observability of **Raft dropped messages** to locate the root cause of slow writes [#17093](https://github.com/tikv/tikv/issues/17093) @[Connor1996](https://github.com/Connor1996) + - Improve the observability of ingest files latency to troubleshoot cluster latency issues [#17078](https://github.com/tikv/tikv/issues/17078) @[LykxSassinator](https://github.com/LykxSassinator) + - Use a separate thread to clean up Region replicas to ensure stable latency on critical Raft reads and writes [#16001](https://github.com/tikv/tikv/issues/16001) @[hbisheng](https://github.com/hbisheng) + - Improve the observability of the number of snapshots being applied [#17078](https://github.com/tikv/tikv/issues/17078) @[hbisheng](https://github.com/hbisheng) + ++ PD + + - Improve the performance of Region heartbeat processing [#7897](https://github.com/tikv/pd/issues/7897) @[nolouch](https://github.com/nolouch) @[rleungx](https://github.com/rleungx) @[JmPotato](https://github.com/JmPotato) + - pd-ctl supports querying hot Regions by the byte or query dimension [#7369](https://github.com/tikv/pd/issues/7369) @[lhy1024](https://github.com/lhy1024) + ++ TiFlash + + - Reduce lock conflicts under highly concurrent data read operations and optimize short query performance [#9125](https://github.com/pingcap/tiflash/issues/9125) @[JinheLin](https://github.com/JinheLin) + - Eliminate redundant copies of the Join Key in the `Join` operator [#9057](https://github.com/pingcap/tiflash/issues/9057) @[gengliqi](https://github.com/gengliqi) + - Concurrently perform the process of converting a two-level hash table in the `HashAgg` operator [#8956](https://github.com/pingcap/tiflash/issues/8956) @[gengliqi](https://github.com/gengliqi) + - Remove redundant aggregation functions for the `HashAgg` operator to reduce computational overhead [#8891](https://github.com/pingcap/tiflash/issues/8891) @[guo-shaoge](https://github.com/guo-shaoge) + ++ Tools + + + Backup & Restore (BR) + + - Optimize the backup feature, improving backup performance and stability during node restarts, cluster scaling-out, and network jitter when backing up large numbers of tables [#52534](https://github.com/pingcap/tidb/issues/52534) @[3pointer](https://github.com/3pointer) + - Implement fine-grained checks of TiCDC changefeed during data restore. If the changefeed [`CheckpointTS`](/ticdc/ticdc-architecture.md#checkpointts) is later than the data backup time, the restore operations are not affected, thereby reducing unnecessary wait times and improving user experience [#53131](https://github.com/pingcap/tidb/issues/53131) @[YuJuncen](https://github.com/YuJuncen) + - Add several commonly used parameters to the [`BACKUP`](/sql-statements/sql-statement-backup.md) statement and the [`RESTORE`](/sql-statements/sql-statement-restore.md) statement, such as `CHECKSUM_CONCURRENCY` [#53040](https://github.com/pingcap/tidb/issues/53040) @[RidRisR](https://github.com/RidRisR) + - Except for the `br log restore` subcommand, all other `br log` subcommands support skipping the loading of the TiDB `domain` data structure to reduce memory consumption [#52088](https://github.com/pingcap/tidb/issues/52088) @[Leavrth](https://github.com/Leavrth) + - Support encryption of temporary files generated during log backup [#15083](https://github.com/tikv/tikv/issues/15083) @[YuJuncen](https://github.com/YuJuncen) + - Add a `tikv_log_backup_pending_initial_scan` monitoring metric in the Grafana dashboard [#16656](https://github.com/tikv/tikv/issues/16656) @[3pointer](https://github.com/3pointer) + - Optimize the output format of PITR logs and add a `RestoreTS` field in the logs [#53645](https://github.com/pingcap/tidb/issues/53645) @[dveeden](https://github.com/dveeden) + + + TiCDC + + - Support directly outputting raw events when the downstream is a Message Queue (MQ) or cloud storage [#11211](https://github.com/pingcap/tiflow/issues/11211) @[CharlesCheung96](https://github.com/CharlesCheung96) + +## Bug fixes + ++ TiDB + + - Fix the issue that when a SQL statement contains an Outer Join and the Join condition includes the `false IN (column_name)` expression, the query result lacks some data [#49476](https://github.com/pingcap/tidb/issues/49476) @[ghazalfamilyusa](https://github.com/ghazalfamilyusa) + - Fix the issue that statistics for columns in system tables are collected when TiDB collects `PREDICATE COLUMNS` statistics for tables [#53403](https://github.com/pingcap/tidb/issues/53403) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `tidb_enable_column_tracking` system variable does not take effect when the `tidb_persist_analyze_options` system variable is set to `OFF` [#53478](https://github.com/pingcap/tidb/issues/53478) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue of potential data races during the execution of `(*PointGetPlan).StatsInfo()` [#49803](https://github.com/pingcap/tidb/issues/49803) [#43339](https://github.com/pingcap/tidb/issues/43339) @[qw4990](https://github.com/qw4990) + - Fix the issue that TiDB might return incorrect query results when you query tables with virtual columns in transactions that involve data modification operations [#53951](https://github.com/pingcap/tidb/issues/53951) @[qw4990](https://github.com/qw4990) + - Fix the issue that the `tidb_enable_async_merge_global_stats` and `tidb_analyze_partition_concurrency` system variables do not take effect during automatic statistics collection [#53972](https://github.com/pingcap/tidb/issues/53972) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that TiDB might return the `plan not supported` error when you query `TABLESAMPLE` [#54015](https://github.com/pingcap/tidb/issues/54015) @[tangenta](https://github.com/tangenta) + - Fix the issue that executing the `SELECT DISTINCT CAST(col AS DECIMAL), CAST(col AS SIGNED) FROM ...` query might return incorrect results [#53726](https://github.com/pingcap/tidb/issues/53726) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that queries cannot be terminated after a data read timeout on the client side [#44009](https://github.com/pingcap/tidb/issues/44009) @[wshwsh12](https://github.com/wshwsh12) + - Fix the overflow issue of the `Longlong` type in predicates [#45783](https://github.com/pingcap/tidb/issues/45783) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the Window function might panic when there is a related subquery in it [#42734](https://github.com/pingcap/tidb/issues/42734) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the TopN operator might be pushed down incorrectly [#37986](https://github.com/pingcap/tidb/issues/37986) @[qw4990](https://github.com/qw4990) + - Fix the issue that `SELECT INTO OUTFILE` does not work when clustered indexes are used as predicates [#42093](https://github.com/pingcap/tidb/issues/42093) @[qw4990](https://github.com/qw4990) + - Fix the issue that the query latency of stale reads increases, caused by information schema cache misses [#53428](https://github.com/pingcap/tidb/issues/53428) @[crazycs520](https://github.com/crazycs520) + - Fix the issue that comparing a column of `YEAR` type with an unsigned integer that is out of range causes incorrect results [#50235](https://github.com/pingcap/tidb/issues/50235) @[qw4990](https://github.com/qw4990) + - Fix the issue that the histogram and TopN in the primary key column statistics are not loaded after restarting TiDB [#37548](https://github.com/pingcap/tidb/issues/37548) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the `final` AggMode and the `non-final` AggMode cannot coexist in Massively Parallel Processing (MPP) [#51362](https://github.com/pingcap/tidb/issues/51362) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that TiDB panics when executing the `SHOW ERRORS` statement with a predicate that is always `true` [#46962](https://github.com/pingcap/tidb/issues/46962) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that using a view does not work in recursive CTE [#49721](https://github.com/pingcap/tidb/issues/49721) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that TiDB might report an error due to GC when loading statistics at startup [#53592](https://github.com/pingcap/tidb/issues/53592) @[you06](https://github.com/you06) + - Fix the issue that `PREPARE`/`EXECUTE` statements with the `CONV` expression containing a `?` argument might result in incorrect query results when executed multiple times [#53505](https://github.com/pingcap/tidb/issues/53505) @[qw4990](https://github.com/qw4990) + - Fix the issue that non-BIGINT unsigned integers might produce incorrect results when compared with strings/decimals [#41736](https://github.com/pingcap/tidb/issues/41736) @[LittleFall](https://github.com/LittleFall) + - Fix the issue that TiDB does not create corresponding statistics metadata (`stats_meta`) when creating a table with foreign keys [#53652](https://github.com/pingcap/tidb/issues/53652) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that certain filter conditions in queries might cause the planner module to report an `invalid memory address or nil pointer dereference` error [#53582](https://github.com/pingcap/tidb/issues/53582) [#53580](https://github.com/pingcap/tidb/issues/53580) [#53594](https://github.com/pingcap/tidb/issues/53594) [#53603](https://github.com/pingcap/tidb/issues/53603) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that executing `CREATE OR REPLACE VIEW` concurrently might result in the `table doesn't exist` error [#53673](https://github.com/pingcap/tidb/issues/53673) @[tangenta](https://github.com/tangenta) + - Fix the issue that the `STATE` field in the `INFORMATION_SCHEMA.TIDB_TRX` table is empty due to the `size` of the `STATE` field not being defined [#53026](https://github.com/pingcap/tidb/issues/53026) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that the `Distinct_count` information in GlobalStats might be incorrect when `tidb_enable_async_merge_global_stats` is disabled [#53752](https://github.com/pingcap/tidb/issues/53752) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue of incorrect WARNINGS information when using Optimizer Hints [#53767](https://github.com/pingcap/tidb/issues/53767) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that negating a time type results in an incorrect value [#52262](https://github.com/pingcap/tidb/issues/52262) @[solotzg](https://github.com/solotzg) + - Fix the issue that `REGEXP()` does not explicitly report an error for empty pattern arguments [#53221](https://github.com/pingcap/tidb/issues/53221) @[yibin87](https://github.com/yibin87) + - Fix the issue that converting JSON to datetime might lose precision in some cases [#53352](https://github.com/pingcap/tidb/issues/53352) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that `JSON_QUOTE()` returns incorrect results in some cases [#37294](https://github.com/pingcap/tidb/issues/37294) @[dveeden](https://github.com/dveeden) + - Fix the issue that executing `ALTER TABLE ... REMOVE PARTITIONING` might cause data loss [#53385](https://github.com/pingcap/tidb/issues/53385) @[mjonss](https://github.com/mjonss) + - Fix the issue that TiDB fails to reject unauthenticated user connections in some cases when using the `auth_socket` authentication plugin [#54031](https://github.com/pingcap/tidb/issues/54031) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that JSON-related functions return errors inconsistent with MySQL in some cases [#53799](https://github.com/pingcap/tidb/issues/53799) @[dveeden](https://github.com/dveeden) + - Fix the issue that the `INDEX_LENGTH` field of partitioned tables in `INFORMATION_SCHEMA.PARTITIONS` is incorrect [#54173](https://github.com/pingcap/tidb/issues/54173) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that the `TIDB_ROW_ID_SHARDING_INFO` field in the `INFORMATION_SCHEMA.TABLES` table is incorrect [#52330](https://github.com/pingcap/tidb/issues/52330) @[tangenta](https://github.com/tangenta) + - Fix the issue that a generated column returns illegal timestamps [#52509](https://github.com/pingcap/tidb/issues/52509) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that setting `max-index-length` causes TiDB to panic when adding indexes using the Distributed eXecution Framework (DXF) [#53281](https://github.com/pingcap/tidb/issues/53281) @[zimulala](https://github.com/zimulala) + - Fix the issue that the illegal column type `DECIMAL(0,0)` can be created in some cases [#53779](https://github.com/pingcap/tidb/issues/53779) @[tangenta](https://github.com/tangenta) + - Fix the issue that using `CURRENT_DATE()` as the default value for a column results in incorrect query results [#53746](https://github.com/pingcap/tidb/issues/53746) @[tangenta](https://github.com/tangenta) + - Fix the issue that the `ALTER DATABASE ... SET TIFLASH REPLICA` statement incorrectly adds TiFlash replicas to the `SEQUENCE` table [#51990](https://github.com/pingcap/tidb/issues/51990) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the `REFERENCED_TABLE_SCHEMA` field in the `INFORMATION_SCHEMA.KEY_COLUMN_USAGE` table is incorrect [#52350](https://github.com/pingcap/tidb/issues/52350) @[wd0517](https://github.com/wd0517) + - Fix the issue that inserting multiple rows in a single statement causes the `AUTO_INCREMENT` column to be discontinuous when `AUTO_ID_CACHE=1` [#52465](https://github.com/pingcap/tidb/issues/52465) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the format of deprecation warnings [#52515](https://github.com/pingcap/tidb/issues/52515) @[dveeden](https://github.com/dveeden) + - Fix the issue that the `TRACE` command is missing in `copr.buildCopTasks` [#53085](https://github.com/pingcap/tidb/issues/53085) @[time-and-fate](https://github.com/time-and-fate) + - Fix the issue that the `memory_quota` hint might not work in subqueries [#53834](https://github.com/pingcap/tidb/issues/53834) @[qw4990](https://github.com/qw4990) + - Fix the issue that improper use of metadata locks might lead to writing anomalous data when using the plan cache under certain circumstances [#53634](https://github.com/pingcap/tidb/issues/53634) @[zimulala](https://github.com/zimulala) + - Fix the issue that after a statement within a transaction is killed by OOM, if TiDB continues to execute the next statement within the same transaction, you might get an error `Trying to start aggressive locking while it's already started` and a panic occurs [#53540](https://github.com/pingcap/tidb/issues/53540) @[MyonKeminta](https://github.com/MyonKeminta) + ++ TiKV + + - Fix the issue that pushing down the `JSON_ARRAY_APPEND()` function to TiKV causes TiKV to panic [#16930](https://github.com/tikv/tikv/issues/16930) @[dbsid](https://github.com/dbsid) + - Fix the issue that the leader does not clean up failed snapshot files in time [#16976](https://github.com/tikv/tikv/issues/16976) @[hbisheng](https://github.com/hbisheng) + - Fix the issue that highly concurrent Coprocessor requests might cause TiKV OOM [#16653](https://github.com/tikv/tikv/issues/16653) @[overvenus](https://github.com/overvenus) + - Fix the issue that changing the `raftstore.periodic-full-compact-start-times` configuration item online might cause TiKV to panic [#17066](https://github.com/tikv/tikv/issues/17066) @[SpadeA-Tang](https://github.com/SpadeA-Tang) + - Fix the failure of `make docker` and `make docker_test` [#17075](https://github.com/tikv/tikv/issues/17075) @[shunki-fujita](https://github.com/shunki-fujita) + - Fix the issue that the **gRPC request sources duration** metric is displayed incorrectly in the monitoring dashboard [#17133](https://github.com/tikv/tikv/issues/17133) @[King-Dylan](https://github.com/King-Dylan) + - Fix the issue that setting the gRPC message compression method via `grpc-compression-type` does not take effect on messages sent from TiKV to TiDB [#17176](https://github.com/tikv/tikv/issues/17176) @[ekexium](https://github.com/ekexium) + - Fix the issue that the output of the `raft region` command in tikv-ctl does not include the Region status information [#17037](https://github.com/tikv/tikv/issues/17037) @[glorv](https://github.com/glorv) + - Fix the issue that CDC and log-backup do not limit the timeout of `check_leader` using the `advance-ts-interval` configuration, causing the `resolved_ts` lag to be too large when TiKV restarts normally in some cases [#17107](https://github.com/tikv/tikv/issues/17107) @[MyonKeminta](https://github.com/MyonKeminta) + ++ PD + + - Fix the issue that `ALTER PLACEMENT POLICY` cannot modify the placement policy [#52257](https://github.com/pingcap/tidb/issues/52257) [#51712](https://github.com/pingcap/tidb/issues/51712) @[jiyfhust](https://github.com/jiyfhust) + - Fix the issue that the scheduling of write hotspots might break placement policy constraints [#7848](https://github.com/tikv/pd/issues/7848) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that down peers might not recover when using Placement Rules [#7808](https://github.com/tikv/pd/issues/7808) @[rleungx](https://github.com/rleungx) + - Fix the issue that a large number of retries occur when canceling resource groups queries [#8217](https://github.com/tikv/pd/issues/8217) @[nolouch](https://github.com/nolouch) + - Fix the issue that manually transferring the PD leader might fail [#8225](https://github.com/tikv/pd/issues/8225) @[HuSharp](https://github.com/HuSharp) + ++ TiFlash + + - Fix the issue of query timeout when executing queries on partitioned tables that contain empty partitions [#9024](https://github.com/pingcap/tiflash/issues/9024) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that in the disaggregated storage and compute architecture, null values might be incorrectly returned in queries after adding non-null columns in DDL operations [#9084](https://github.com/pingcap/tiflash/issues/9084) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that the `SUBSTRING_INDEX()` function might cause TiFlash to crash in some corner cases [#9116](https://github.com/pingcap/tiflash/issues/9116) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that a large number of duplicate rows might be read in FastScan mode after importing data via BR or TiDB Lightning [#9118](https://github.com/pingcap/tiflash/issues/9118) @[JinheLin](https://github.com/JinheLin) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that BR fails to restore a transactional KV cluster due to an empty `EndKey` [#52574](https://github.com/pingcap/tidb/issues/52574) @[3pointer](https://github.com/3pointer) + - Fix the issue that a PD connection failure could cause the TiDB instance where the log backup advancer owner is located to panic [#52597](https://github.com/pingcap/tidb/issues/52597) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that log backup might be paused after the advancer owner migration [#53561](https://github.com/pingcap/tidb/issues/53561) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that BR fails to correctly identify errors due to multiple nested retries during the restore process [#54053](https://github.com/pingcap/tidb/issues/54053) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that the connection used to fetch TiKV configurations might not be closed [#52595](https://github.com/pingcap/tidb/issues/52595) @[RidRisR](https://github.com/RidRisR) + - Fix the issue that the `TestStoreRemoved` test case is unstable [#52791](https://github.com/pingcap/tidb/issues/52791) @[YuJuncen](https://github.com/YuJuncen) + - Fix the issue that TiFlash crashes during point-in-time recovery (PITR) [#52628](https://github.com/pingcap/tidb/issues/52628) @[RidRisR](https://github.com/RidRisR) + - Fix the inefficiency issue in scanning DDL jobs during incremental backups [#54139](https://github.com/pingcap/tidb/issues/54139) @[3pointer](https://github.com/3pointer) + - Fix the issue that the backup performance during checkpoint backups is affected due to interruptions in seeking Region leaders [#17168](https://github.com/tikv/tikv/issues/17168) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Fix inaccurate display of the **Kafka Outgoing Bytes** panel in Grafana [#10777](https://github.com/pingcap/tiflow/issues/10777) @[asddongmen](https://github.com/asddongmen) + - Fix the issue that data inconsistency might occur when restarting Changefeed repeatedly when performing a large number of `UPDATE` operations in a multi-node environment [#11219](https://github.com/pingcap/tiflow/issues/11219) @[lidezhu](https://github.com/lidezhu) + + + TiDB Data Migration (DM) + + - Fix the connection blocking issue by upgrading `go-mysql` [#11041](https://github.com/pingcap/tiflow/issues/11041) @[D3Hunter](https://github.com/D3Hunter) + - Fix the issue that `SET` statements cause DM to panic during the migration of MariaDB data [#10206](https://github.com/pingcap/tiflow/issues/10206) @[dveeden](https://github.com/dveeden) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning might report an error when importing zstd compressed files [#53587](https://github.com/pingcap/tidb/issues/53587) @[lance6716](https://github.com/lance6716) + + + Dumpling + + - Fix the issue that Dumpling reports an error when exporting tables and views at the same time [#53682](https://github.com/pingcap/tidb/issues/53682) @[tangenta](https://github.com/tangenta) + + + TiDB Binlog + + - Fix the issue that deleting rows during the execution of `ADD COLUMN` might report an error `data and columnID count not match` when TiDB Binlog is enabled [#53133](https://github.com/pingcap/tidb/issues/53133) @[tangenta](https://github.com/tangenta) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [CabinfeverB](https://github.com/CabinfeverB) +- [DanRoscigno](https://github.com/DanRoscigno) (First-time contributor) +- [ei-sugimoto](https://github.com/ei-sugimoto) (First-time contributor) +- [eltociear](https://github.com/eltociear) +- [jiyfhust](https://github.com/jiyfhust) +- [michaelmdeng](https://github.com/michaelmdeng) (First-time contributor) +- [mittalrishabh](https://github.com/mittalrishabh) +- [onlyacat](https://github.com/onlyacat) +- [qichengzx](https://github.com/qichengzx) (First-time contributor) +- [SeaRise](https://github.com/SeaRise) +- [shawn0915](https://github.com/shawn0915) +- [shunki-fujita](https://github.com/shunki-fujita) (First-time contributor) +- [tonyxuqqi](https://github.com/tonyxuqqi) +- [wwu](https://github.com/wwu) (First-time contributor) +- [yzhan1](https://github.com/yzhan1) diff --git a/releases/release-8.3.0.md b/releases/release-8.3.0.md new file mode 100644 index 0000000000000..5f4693a2f947c --- /dev/null +++ b/releases/release-8.3.0.md @@ -0,0 +1,436 @@ +--- +title: TiDB 8.3.0 Release Notes +summary: Learn about the new features, compatibility changes, improvements, and bug fixes in TiDB 8.3.0. +--- + +# TiDB 8.3.0 Release Notes + +Release date: August 22, 2024 + +TiDB version: 8.3.0 + +Quick access: [Quick start](https://docs.pingcap.com/tidb/v8.3/quick-start-with-tidb) + +8.3.0 introduces the following key features and improvements: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CategoryFeature/EnhancementDescription
Scalability and Performance Global indexes for partitioned tables (experimental)Global indexes can effectively improve the efficiency of retrieving non-partitioned columns, and remove the restriction that a unique key must contain the partition key. This feature extends the usage scenarios of TiDB partitioned tables and avoids some of the application modification work that might be required for data migration.
Default pushdown of the Projection operator to the storage enginePushing the Projection operator down to the storage engine can distribute the load across storage nodes while reducing data transfer between nodes. This optimization helps to reduce the execution time for certain SQL queries and improves the overall database performance.
Ignoring unnecessary columns when collecting statisticsUnder the premise of ensuring that the optimizer can obtain the necessary information, TiDB speeds up statistics collection, improves the timeliness of statistics, and thus ensures that the optimal execution plan is selected, improving the performance of the cluster. Meanwhile, TiDB also reduces the system overhead and improves the resource utilization.
Reliability and AvailabilityBuilt-in virtual IP management in TiProxyTiProxy introduces built-in virtual IP management. When configured, it supports automatic virtual IP switching without relying on external platforms or tools. This feature simplifies TiProxy deployment and reduces the complexity of the database access layer.
+ +## Feature details + +### Performance + +* The optimizer allows pushing the `Projection` operator down to the storage engine by default [#51876](https://github.com/pingcap/tidb/issues/51876) @[yibin87](https://github.com/yibin87) + + Pushing the `Projection` operator down to the storage engine reduces data transfer between the compute engine and the storage engine, thereby improving SQL execution performance. This is particularly effective for queries containing [JSON query functions](/functions-and-operators/json-functions/json-functions-search.md) or [JSON value attribute functions](/functions-and-operators/json-functions/json-functions-return.md). Starting from v8.3.0, TiDB enables the `Projection` operator pushdown feature by default, by changing the default value of the system variable controlling this feature, [`tidb_opt_projection_push_down`](/system-variables.md#tidb_opt_projection_push_down-new-in-v610), from `OFF` to `ON`. When this feature is enabled, the optimizer automatically pushes eligible JSON query functions and JSON value attribute functions down to the storage engine. + + For more information, see [documentation](/system-variables.md#tidb_opt_projection_push_down-new-in-v610). + +* Optimize batch processing strategy for KV (key-value) requests [#55206](https://github.com/pingcap/tidb/issues/55206) @[zyguan](https://github.com/zyguan) + + TiDB fetches data by sending KV requests to TiKV. Batching and processing KV requests in bulk can significantly improve execution performance. Before v8.3.0, the batching strategy in TiDB is less efficient. Starting from v8.3.0, TiDB introduces several more efficient batching strategies in addition to the existing one. You can configure different batching strategies using the [`tikv-client.batch-policy`](/tidb-configuration-file.md#batch-policy-new-in-v830) configuration item to accommodate various workloads. + + For more information, see [documentation](/tidb-configuration-file.md#batch-policy-new-in-v830). + +* TiFlash introduces HashAgg aggregation calculation modes to improve the performance for high NDV data [#9196](https://github.com/pingcap/tiflash/issues/9196) @[guo-shaoge](https://github.com/guo-shaoge) + + Before v8.3.0, TiFlash has low aggregation calculation efficiency during the first stage of HashAgg aggregation when handling data with high NDV (number of distinct values). Starting from v8.3.0, TiFlash introduces multiple HashAgg aggregation calculation modes to improve the aggregation performance for different data characteristics. To choose a desired HashAgg aggregation calculation mode, you can configure the [`tiflash_hashagg_preaggregation_mode`](/system-variables.md#tiflash_hashagg_preaggregation_mode-new-in-v830) system variable. + + For more information, see [documentation](/system-variables.md#tiflash_hashagg_preaggregation_mode-new-in-v830). + +* Ignore unnecessary columns when collecting statistics [#53567](https://github.com/pingcap/tidb/issues/53567) @[hi-rustin](https://github.com/Rustin170506) + + When the optimizer generates an execution plan, it only needs statistics for some columns, such as columns in the filter conditions, columns in the join keys, and columns used for aggregation. Starting from v8.3.0, TiDB continuously observes the historical records of the columns used in SQL statements. By default, TiDB only collects statistics for columns with indexes and columns that are observed to require statistics collection. This speeds up the collection of statistics and avoids unnecessary resource consumption. + + When you upgrade your cluster from a version earlier than v8.3.0 to v8.3.0 or later, TiDB retains the original behavior by default, that is, collecting statistics for all columns. To enable this feature, you need to manually set the system variable [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830) to `PREDICATE`. For newly deployed clusters, this feature is enabled by default. + + For analytical systems with many random queries, you can set the system variable [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830) to `ALL` to collect statistics for all columns, to ensure the performance of random queries. For other types of systems, it is recommended to keep the default setting (`PREDICATE`) of [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830) to collect statistics for only necessary columns. + + For more information, see [documentation](/statistics.md#collect-statistics-on-some-columns). + +* Improve the query performance of some system tables [#50305](https://github.com/pingcap/tidb/issues/50305) @[tangenta](https://github.com/tangenta) + + In previous versions, querying system tables has poor performance when the cluster size becomes large and there are a large number of tables. + + In v8.0.0, query performance is optimized for the following four system tables: + + - `INFORMATION_SCHEMA.TABLES` + - `INFORMATION_SCHEMA.STATISTICS` + - `INFORMATION_SCHEMA.KEY_COLUMN_USAGE` + - `INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS` + + In v8.3.0, the query performance is optimized for the following system tables, bringing a multi-fold performance improvement compared to v8.2.0. + + - `INFORMATION_SCHEMA.CHECK_CONSTRAINTS` + - `INFORMATION_SCHEMA.COLUMNS` + - `INFORMATION_SCHEMA.PARTITIONS` + - `INFORMATION_SCHEMA.SCHEMATA` + - `INFORMATION_SCHEMA.SEQUENCES` + - `INFORMATION_SCHEMA.TABLE_CONSTRAINTS` + - `INFORMATION_SCHEMA.TIDB_CHECK_CONSTRAINTS` + - `INFORMATION_SCHEMA.TiDB_INDEXES` + - `INFORMATION_SCHEMA.TIDB_INDEX_USAGE` + - `INFORMATION_SCHEMA.VIEWS` + +* Support partition pruning when partition expressions use the `EXTRACT(YEAR_MONTH...)` function to improve query performance [#54209](https://github.com/pingcap/tidb/pull/54209) @[mjonss](https://github.com/mjonss) + + In previous versions, when partition expressions use the `EXTRACT(YEAR_MONTH...)` function, partition pruning is not supported, resulting in poor query performance. Starting from v8.3.0, partition pruning is supported when partition expressions use the `EXTRACT(YEAR_MONTH...)` function, which improves query performance. + + For more information, see [documentation](/partition-pruning.md#scenario-three). + +* Improve the performance of `CREATE TABLE` by 1.4 times, `CREATE DATABASE` by 2.1 times, and `ADD COLUMN` by 2 times [#54436](https://github.com/pingcap/tidb/issues/54436) @[D3Hunter](https://github.com/D3Hunter) + + TiDB v8.0.0 introduces the system variable [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800) to improve table creation performance in batch table creation scenarios. In v8.3.0, when submitting the DDL statements for table creation concurrently through 10 sessions in a single database, the performance is improved by 1.4 times compared with v8.2.0. + + In v8.3.0, the performance of general DDLs in batch execution has improved compared to v8.2.0. The performance of `CREATE DATABASE` for 10 sessions concurrently improves by 19 times compared with v8.1.0 and 2.1 times compared with v8.2.0. The performance of using 10 sessions to add columns (`ADD COLUMN`) to multiple tables in the same database in batch has improved by 10 times compared with v8.1.0, and 2.1 times compared with v8.2.0. The performance of `ADD COLUMN` with 10 sessions on multiple tables in the same database has improved by 10 times compared with v8.1.0 and 2 times compared with v8.2.0. + + For more information, see [documentation](/system-variables.md#tidb_enable_fast_create_table-new-in-v800). + +* Partitioned tables support global indexes (experimental) [#45133](https://github.com/pingcap/tidb/issues/45133) @[mjonss](https://github.com/mjonss) @[Defined2014](https://github.com/Defined2014) @[jiyfhust](https://github.com/jiyfhust) @[L-maple](https://github.com/L-maple) + + In previous versions of partitioned tables, some limitations exist because global indexes are not supported. For example, the unique key must use every column in the table's partitioning expression. If the query condition does not use the partitioning key, the query will scan all partitions, resulting in poor performance. Starting from v7.6.0, the system variable [`tidb_enable_global_index`](/system-variables.md#tidb_enable_global_index-new-in-v760) is introduced to enable the global index feature. But this feature was under development at that time and it is not recommended to enable it. + + Starting with v8.3.0, the global index feature is released as an experimental feature. You can explicitly create a global index for a partitioned table with the keyword `Global` to remove the restriction that the unique key must use every column in the table's partitioning expression, to meet flexible business needs. Global indexes also enhance the performance of queries that do not include partition keys. + + For more information, see [documentation](/partitioned-table.md#global-indexes). + +### Reliability + +* Support streaming cursor result sets (experimental) [#54526](https://github.com/pingcap/tidb/issues/54526) @[YangKeao](https://github.com/YangKeao) + + When the application code retrieves the result set using [Cursor Fetch](/develop/dev-guide-connection-parameters.md#use-streamingresult-to-get-the-execution-result), TiDB usually first stores the complete result set in memory, and then returns the data to the client in batches. If the result set is too large, TiDB might temporarily write the result to the hard disk. + + Starting from v8.3.0, if you set the system variable [`tidb_enable_lazy_cursor_fetch`](/system-variables.md#tidb_enable_lazy_cursor_fetch-new-in-v830) to `ON`, TiDB no longer reads all data to the TiDB node, but gradually reads data to the TiDB node as the client reads. When TiDB processes large result sets, this feature reduces the memory usage of the TiDB node and improves the stability of the cluster. + + For more information, see [documentation](/system-variables.md#tidb_enable_lazy_cursor_fetch-new-in-v830). + +* Enhance SQL execution plan binding [#55280](https://github.com/pingcap/tidb/issues/55280) [#55343](https://github.com/pingcap/tidb/issues/55343) @[time-and-fate](https://github.com/time-and-fate) + + In OLTP scenarios, the optimal execution plan for most SQL statements is fixed. Implementing SQL execution plan binding for important SQL statements in the application can reduce the probability of the execution plan becoming worse and improve system stability. To meet the requirements of creating a large number of SQL execution plan bindings, TiDB enhances the capability and experience of SQL binding, including: + + - Use a single SQL statement to create SQL execution plan bindings from multiple historical execution plans to improve the efficiency of creating bindings. + - The SQL execution plan binding supports more optimizer hints, and optimizes the conversion method for complex execution plans, making the binding more stable in restoring the execution plan. + + For more information, see [documentation](/sql-plan-management.md). + +### Availability + +* TiProxy supports built-in virtual IP management [#583](https://github.com/pingcap/tiproxy/issues/583) @[djshow832](https://github.com/djshow832) + + Before v8.3.0, when using primary-secondary mode for high availability, TiProxy requires an additional component to manage the virtual IP address. Starting from v8.3.0, TiProxy supports built-in virtual IP management. In primary-secondary mode, when a primary node fails over, the new primary node will automatically bind to the specified virtual IP, ensuring that clients can always connect to an available TiProxy through the virtual IP. + + To enable virtual IP management, specify the virtual IP address using the TiProxy configuration item [`ha.virtual-ip`](/tiproxy/tiproxy-configuration.md#virtual-ip) and specify the network interface to bind the virtual IP to using [`ha.interface`](/tiproxy/tiproxy-configuration.md#interface). The virtual IP will be bound to a TiProxy instance only when both of these configuration items are set. + + For more information, see [documentation](/tiproxy/tiproxy-overview.md). + +### SQL + +* Support upgrading `SELECT LOCK IN SHARE MODE` to exclusive locks [#54999](https://github.com/pingcap/tidb/issues/54999) @[cfzjywxk](https://github.com/cfzjywxk) + + TiDB does not support `SELECT LOCK IN SHARE MODE` yet. Starting from v8.3.0, TiDB supports upgrading `SELECT LOCK IN SHARE MODE` to exclusive locks to enable support for `SELECT LOCK IN SHARE MODE`. You can control whether to enable this feature by using the new system variable [`tidb_enable_shared_lock_promotion`](/system-variables.md#tidb_enable_shared_lock_promotion-new-in-v830). + + For more information, see [documentation](/system-variables.md#tidb_enable_shared_lock_promotion-new-in-v830). + +### Observability + +* Show the progress of loading initial statistics [#53564](https://github.com/pingcap/tidb/issues/53564) @[hawkingrei](https://github.com/hawkingrei) + + TiDB loads basic statistics when it starts. In scenarios with many tables or partitions, this process can take a long time. When the configuration item [`force-init-stats`](/tidb-configuration-file.md#force-init-stats-new-in-v657-and-v710) is set to `ON`, TiDB does not provide services until the initial statistics are loaded. In this case, you need to observe the loading process to estimate the service start time. + + Starting from v8.3.0, TiDB prints the progress of loading initial statistics in stages in the log, so you can understand the running status. To provide formatted results to external tools, TiDB adds the additional [monitoring API](/tidb-monitoring-api.md) so you can obtain the progress of loading initial statistics at any time during the startup phase. + +* Add metrics about Request Unit (RU) settings [#8444](https://github.com/tikv/pd/issues/8444) @[nolouch](https://github.com/nolouch) + +### Security + +* Enhance PD log redaction [#8305](https://github.com/tikv/pd/issues/8305) @[JmPotato](https://github.com/JmPotato) + + TiDB v8.0.0 enhances log redaction and supports marking user data in TiDB logs with `‹ ›`. Based on the marked logs, you can decide whether to redact the marked information when displaying the logs, thus increasing the flexibility of log redaction. In v8.2.0, TiFlash implements a similar log redaction enhancement. + + In v8.3.0, PD implements a similar log redaction enhancement. To use this feature, you can set the value of the PD configuration item `security.redact-info-log` to `"marker"`. + + For more information, see [documentation](/log-redaction.md#log-redaction-in-pd-side). + +* Enhance TiKV log redaction [#17206](https://github.com/tikv/tikv/issues/17206) @[lucasliang](https://github.com/LykxSassinator) + + TiDB v8.0.0 enhances log redaction and supports marking user data in TiDB logs with `‹ ›`. Based on the marked logs, you can decide whether to redact the marked information when displaying the logs, thus increasing the flexibility of log redaction. In v8.2.0, TiFlash implements a similar log redaction enhancement. + + In v8.3.0, TiKV implements a similar log redaction enhancement. To use this feature, you can set the value of the TiKV configuration item `security.redact-info-log` to `"marker"`. + + For more information, see [documentation](/log-redaction.md#log-redaction-in-tikv-side). + +### Data migration + +* TiCDC supports replicating DDL statements in bi-directional replication (BDR) mode (GA) [#10301](https://github.com/pingcap/tiflow/issues/10301) [#48519](https://github.com/pingcap/tidb/issues/48519) @[okJiang](https://github.com/okJiang) @[asddongmen](https://github.com/asddongmen) + + TiCDC v7.6.0 introduced the replication of DDL statements with bi-directional replication configured. Previously, bi-directional replication of DDL statements was not supported by TiCDC, so users of TiCDC's bi-directional replication had to execute DDL statements on both TiDB clusters separately. With this feature, after assigning a `PRIMARY` BDR role to a cluster, TiCDC can replicate the DDL statements from that cluster to the `SECONDARY` cluster. + + In v8.3.0, this feature becomes generally available (GA). + + For more information, see [documentation](/ticdc/ticdc-bidirectional-replication.md). + +## Compatibility changes + +> **Note:** +> +> This section provides compatibility changes you need to know when you upgrade from v8.2.0 to the current version (v8.3.0). If you are upgrading from v8.1.0 or earlier versions to the current version, you might also need to check the compatibility changes introduced in intermediate versions. + +### Behavior changes + +* To avoid incorrect use of commands, `pd-ctl` cancels the prefix matching mechanism. For example, `store remove-tombstone` cannot be called via `store remove` [#8413](https://github.com/tikv/pd/issues/8413) @[lhy1024](https://github.com/lhy1024) + +### System variables + +| Variable name | Change type | Description | +|--------|------------------------------|------| +| [`tidb_ddl_reorg_batch_size`](/system-variables.md#tidb_ddl_reorg_batch_size) | Modified | Adds the SESSION scope. | +| [`tidb_ddl_reorg_worker_cnt`](/system-variables.md#tidb_ddl_reorg_worker_cnt) | Modified | Adds the SESSION scope. | +| [`tidb_gc_concurrency`](/system-variables.md#tidb_gc_concurrency-new-in-v50) | Modified | Starting from v8.3.0, this variable controls the number of concurrent threads during the [Resolve Locks](/garbage-collection-overview.md#resolve-locks) and [Delete Range](/garbage-collection-overview.md#delete-ranges) steps of the [Garbage Collection (GC)](/garbage-collection-overview.md) process. Before v8.3.0, this variable only controls the number of threads during the [Resolve Locks](/garbage-collection-overview.md#resolve-locks) step. | +| [`tidb_low_resolution_tso`](/system-variables.md#tidb_low_resolution_tso) | Modified | Adds the GLOBAL scope. | +| [`tidb_opt_projection_push_down`](/system-variables.md#tidb_opt_projection_push_down-new-in-v610) | Modified | Adds the GLOBAL scope and persists the variable value to the cluster. Changes the default value from `OFF` to `ON` after further tests, which means that the optimizer is allowed to push `Projection` down to the TiKV coprocessor. | +| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830) | Newly added | Controls the behavior of the `ANALYZE TABLE` statement. Setting it to the default value `PREDICATE` means only collecting statistics for [predicate columns](/statistics.md#collect-statistics-on-some-columns); setting it to `ALL` means collecting statistics for all columns. | +| [`tidb_enable_lazy_cursor_fetch`](/system-variables.md#tidb_enable_lazy_cursor_fetch-new-in-v830) | Newly added | Controls the behavior of the [Cursor Fetch](/develop/dev-guide-connection-parameters.md#use-streamingresult-to-get-the-execution-result) feature. | +| [`tidb_enable_shared_lock_promotion`](/system-variables.md#tidb_enable_shared_lock_promotion-new-in-v830) | Newly added | Controls whether to enable the feature of upgrading shared locks to exclusive locks. The default value of this variable is `OFF`, which means that the function of upgrading shared locks to exclusive locks is disabled. | +| [`tiflash_hashagg_preaggregation_mode`](/system-variables.md#tiflash_hashagg_preaggregation_mode-new-in-v830) | Newly added | Controls the pre-aggregation strategy used during the first stage of two-stage or three-stage HashAgg operations pushed down to TiFlash. | + +### Configuration file parameters + +| Configuration file | Configuration parameter | Change type | Description | +| -------- | -------- | -------- | -------- | +| TiDB | [`tikv-client.batch-policy`](/tidb-configuration-file.md#batch-policy-new-in-v830) | Newly added | Controls the batching strategy for requests from TiDB to TiKV. | +| PD | [`security.redact-info-log`](/pd-configuration-file.md#redact-info-log-new-in-v50) | Modified | Support setting the value of the PD configuration item `security.redact-info-log` to `"marker"` to mark sensitive information in the log with `‹ ›` instead of shielding it directly. With the `"marker"` option, you can customize the redaction rules. | +| TiKV | [`security.redact-info-log`](/tikv-configuration-file.md#redact-info-log-new-in-v408) | Modified | Support setting the value of the TiKV configuration item `security.redact-info-log` to `"marker"` to mark sensitive information in the log with `‹ ›` instead of shielding it directly. With the `"marker"` option, you can customize the redaction rules. | +| TiFlash | [`security.redact-info-log`](/tiflash/tiflash-configuration.md#configure-the-tiflash-learnertoml-file) | Modified | Support setting the value of the TiFlash Learner configuration item `security.redact-info-log` to `"marker"` to mark sensitive information in the log with `‹ ›` instead of shielding it directly. With the `"marker"` option, you can customize the redaction rules. | +| BR | [`--allow-pitr-from-incremental`](/br/br-incremental-guide.md#limitations) | Newly added | Controls whether incremental backups are compatible with subsequent log backups. The default value is `true`, which means that incremental backups are compatible with subsequent log backups. When you keep the default value `true`, the DDLs that need to be replayed are strictly checked before the incremental restore begins. | + +### System tables + +* The [`INFORMATION_SCHEMA.PROCESSLIST`](/information-schema/information-schema-processlist.md) and [`INFORMATION_SCHEMA.CLUSTER_PROCESSLIST`](/information-schema/information-schema-processlist.md#cluster_processlist) system tables add the `SESSION_ALIAS` field to show the number of rows currently affected by the DML statement [#46889](https://github.com/pingcap/tidb/issues/46889) @[lcwangchao](https://github.com/lcwangchao) + +## Deprecated features + +* The following features are deprecated starting from v8.3.0: + + * Starting from v7.5.0, [TiDB Binlog](/tidb-binlog/tidb-binlog-overview.md) replication is deprecated. Starting from v8.3.0, TiDB Binlog is fully deprecated, with removal planned for a future release. For incremental data replication, use [TiCDC](/ticdc/ticdc-overview.md) instead. For point-in-time recovery (PITR), use [PITR](/br/br-pitr-guide.md). + * Starting from v8.3.0, the [`tidb_enable_column_tracking`](/system-variables.md#tidb_enable_column_tracking-new-in-v540) system variable is deprecated. TiDB tracks predicate columns by default. For more information, see [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830). + +* The following features are planned for deprecation in future versions: + + * TiDB introduces the system variable [`tidb_enable_auto_analyze_priority_queue`](/system-variables.md#tidb_enable_auto_analyze_priority_queue-new-in-v800), which controls whether priority queues are enabled to optimize the ordering of tasks that automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. + * TiDB introduces the system variable [`tidb_enable_async_merge_global_stats`](/system-variables.md#tidb_enable_async_merge_global_stats-new-in-v750) in v7.5.0. You can use it to set TiDB to use asynchronous merging of partition statistics to avoid OOM issues. In future releases, partition statistics will be merged asynchronously, so this system variable will be deprecated. + * It is planned to redesign [the automatic evolution of execution plan bindings](/sql-plan-management.md#baseline-evolution) in subsequent releases, and the related variables and behavior will change. + * In v8.0.0, TiDB introduces the [`tidb_enable_parallel_hashagg_spill`](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800) system variable to control whether TiDB supports disk spill for the concurrent HashAgg algorithm. In future versions, the [`tidb_enable_parallel_hashagg_spill`](/system-variables.md#tidb_enable_parallel_hashagg_spill-new-in-v800) system variable will be deprecated. + * The TiDB Lightning parameter [`conflict.max-record-rows`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) is planned for deprecation in a future release and will be subsequently removed. This parameter will be replaced by [`conflict.threshold`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task), which means that the maximum number of conflicting records is consistent with the maximum number of conflicting records that can be tolerated in a single import task. + +* The following features are planned for removal in future versions: + + * Starting from v8.0.0, TiDB Lightning deprecates the [old version of conflict detection](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#the-old-version-of-conflict-detection-deprecated-in-v800) strategy for the physical import mode, and enables you to control the conflict detection strategy for both logical and physical import modes via the [`conflict.strategy`](/tidb-lightning/tidb-lightning-configuration.md#tidb-lightning-task) parameter. The [`duplicate-resolution`](/tidb-lightning/tidb-lightning-configuration.md) parameter for the old version of conflict detection will be removed in a future release. + +## Improvements + ++ TiDB + + - Support the `SELECT ... STRAIGHT_JOIN ... USING ( ... )` statement [#54162](https://github.com/pingcap/tidb/issues/54162) @[dveeden](https://github.com/dveeden) + - Construct more precise index access ranges for filter conditions like `((idx_col_1 > 1) or (idx_col_1 = 1 and idx_col_2 > 10)) and ((idx_col_1 < 10) or (idx_col_1 = 10 and idx_col_2 < 20))` [#54337](https://github.com/pingcap/tidb/issues/54337) @[ghazalfamilyusa](https://github.com/ghazalfamilyusa) + - Use index order to avoid extra sorting operations for SQL queries like `WHERE idx_col_1 IS NULL ORDER BY idx_col_2` [#54188](https://github.com/pingcap/tidb/issues/54188) @[ari-e](https://github.com/ari-e) + - Display analyzed indexes in the `mysql.analyze_jobs` system table [#53567](https://github.com/pingcap/tidb/issues/53567) @[hi-rustin](https://github.com/Rustin170506) + - Support applying the `tidb_redact_log` setting to the output of `EXPLAIN` statements [#54565](https://github.com/pingcap/tidb/issues/54565) @[hawkingrei](https://github.com/hawkingrei) + - Support generating the `Selection` operator on `IndexRangeScan` for multi-valued indexes to improve query efficiency [#54876](https://github.com/pingcap/tidb/issues/54876) @[time-and-fate](https://github.com/time-and-fate) + - Support killing automatic `ANALYZE` tasks that are running outside the set time window [#55283](https://github.com/pingcap/tidb/issues/55283) @[hawkingrei](https://github.com/hawkingrei) + - Adjust estimation results from 0 to 1 for equality conditions that do not hit TopN when statistics are entirely composed of TopN and the modified row count in the corresponding table statistics is non-zero [#47400](https://github.com/pingcap/tidb/issues/47400) @[terry1purcell](https://github.com/terry1purcell) + - The TopN operator supports disk spill [#47733](https://github.com/pingcap/tidb/issues/47733) @[xzhangxian1008](https://github.com/xzhangxian1008) + - TiDB node supports executing queries with the `WITH ROLLUP` modifier and the `GROUPING` function [#42631](https://github.com/pingcap/tidb/issues/42631) @[Arenatlx](https://github.com/Arenatlx) + - The system variable [`tidb_low_resolution_tso`](/system-variables.md#tidb_low_resolution_tso) supports the `GLOBAL` scope [#55022](https://github.com/pingcap/tidb/issues/55022) @[cfzjywxk](https://github.com/cfzjywxk) + - Improve GC (Garbage Collection) efficiency by supporting concurrent range deletion. You can control the number of concurrent threads using [`tidb_gc_concurrency`](/system-variables.md#tidb_gc_concurrency-new-in-v50) [#54570](https://github.com/pingcap/tidb/issues/54570) @[ekexium](https://github.com/ekexium) + - Improve the performance of bulk DML execution mode (`tidb_dml_type = "bulk"`) [#50215](https://github.com/pingcap/tidb/issues/50215) @[ekexium](https://github.com/ekexium) + - Improve the performance of schema information cache-related interface `SchemaByID` [#54074](https://github.com/pingcap/tidb/issues/54074) @[ywqzzy](https://github.com/ywqzzy) + - Improve the query performance for certain system tables when schema information caching is enabled [#50305](https://github.com/pingcap/tidb/issues/50305) @[tangenta](https://github.com/tangenta) + - Optimize error messages for conflicting keys when adding unique indexes [#53004](https://github.com/pingcap/tidb/issues/53004) @[lance6716](https://github.com/lance6716) + ++ PD + + - Support modifying the `batch` configuration of the `evict-leader-scheduler` via `pd-ctl` to accelerate the leader eviction process [#8265](https://github.com/tikv/pd/issues/8265) @[rleungx](https://github.com/rleungx) + - Add the `store_id` monitoring metric to the **Cluster > Label distribution** panel in Grafana to display store IDs corresponding to different labels [#8337](https://github.com/tikv/pd/issues/8337) @[HuSharp](https://github.com/HuSharp) + - Support fallback to the default resource group when the specified resource group does not exist [#8388](https://github.com/tikv/pd/issues/8388) @[JmPotato](https://github.com/JmPotato) + - Add the `approximate_kv_size` field to the Region information output by the `region` command in `pd-ctl` [#8412](https://github.com/tikv/pd/issues/8412) @[zeminzhou](https://github.com/zeminzhou) + - Optimize the message that returns when you call the PD API to delete the TTL configuration [#8450](https://github.com/tikv/pd/issues/8450) @[lhy1024](https://github.com/lhy1024) + - Optimize the RU consumption behavior of large query read requests to reduce the impact on other requests [#8457](https://github.com/tikv/pd/issues/8457) @[nolouch](https://github.com/nolouch) + - Optimize the error message that returns when you misconfigure PD microservices [#52912](https://github.com/pingcap/tidb/issues/52912) @[rleungx](https://github.com/rleungx) + - Add the `--name` startup parameter to PD microservices to more accurately display the service name during deployment [#7995](https://github.com/tikv/pd/issues/7995) @[HuSharp](https://github.com/HuSharp) + - Support dynamically adjusting `PatrolRegionScanLimit` based on the number of Regions to reduce Region scan time [#7963](https://github.com/tikv/pd/issues/7963) @[lhy1024](https://github.com/lhy1024) + ++ TiKV + + - Optimize the batching policy for writing Raft logs when `async-io` is enabled to reduce the consumption of disk I/O bandwidth resources [#16907](https://github.com/tikv/tikv/issues/16907) @[LykxSassinator](https://github.com/LykxSassinator) + - Redesign the TiCDC delegate and downstream modules to better support Region partial subscription [#16362](https://github.com/tikv/tikv/issues/16362) @[hicqu](https://github.com/hicqu) + - Reduce the size of a single slow query log [#17294](https://github.com/tikv/tikv/issues/17294) @[Connor1996](https://github.com/Connor1996) + - Add a new monitoring metric `min safe ts` [#17307](https://github.com/tikv/tikv/issues/17307) @[mittalrishabh](https://github.com/mittalrishabh) + - Reduce the memory usage of the peer message channel [#16229](https://github.com/tikv/tikv/issues/16229) @[Connor1996](https://github.com/Connor1996) + ++ TiFlash + + - Support generating ad hoc heap profiling in SVG format [#9320](https://github.com/pingcap/tiflash/issues/9320) @[CalvinNeo](https://github.com/CalvinNeo) + ++ Tools + + + Backup & Restore (BR) + + - Support checking whether a full backup exists before starting point-in-time recovery (PITR) for the first time. If the full backup is not found, BR terminates the restore and returns an error [#54418](https://github.com/pingcap/tidb/issues/54418) @[Leavrth](https://github.com/Leavrth) + - Support checking whether the disk space in TiKV and TiFlash is sufficient before restoring snapshot backups. If the space is insufficient, BR terminates the restore and returns an error [#54316](https://github.com/pingcap/tidb/issues/54316) @[RidRisR](https://github.com/RidRisR) + - Support checking whether the disk space in TiKV is sufficient before TiKV downloads each SST file. If the space is insufficient, BR terminates the restore and returns an error [#17224](https://github.com/tikv/tikv/issues/17224) @[RidRisR](https://github.com/RidRisR) + - Support setting Alibaba Cloud access credentials through environment variables [#45551](https://github.com/pingcap/tidb/issues/45551) @[RidRisR](https://github.com/RidRisR) + - Optimize the backup feature, improving backup performance and stability during node restarts, cluster scaling-out, and network jitter when backing up large numbers of tables [#52534](https://github.com/pingcap/tidb/issues/52534) @[3pointer](https://github.com/3pointer) + - Automatically set the environment variable `GOMEMLIMIT` based on the available memory of the BR process to avoid OOM when using BR for backup and restore [#53777](https://github.com/pingcap/tidb/issues/53777) @[Leavrth](https://github.com/Leavrth) + - Make incremental backups compatible with point-in-time recovery (PITR) [#54474](https://github.com/pingcap/tidb/issues/54474) @[3pointer](https://github.com/3pointer) + - Support backing up and restoring the `mysql.column_stats_usage` table [#53567](https://github.com/pingcap/tidb/issues/53567) @[hi-rustin](https://github.com/Rustin170506) + +## Bug fixes + ++ TiDB + + - Reset the parameters in the `Open` method of `PipelinedWindow` to fix the unexpected error that occurs when the `PipelinedWindow` is used as a child node of `Apply` due to the reuse of previous parameter values caused by repeated opening and closing operations [#53600](https://github.com/pingcap/tidb/issues/53600) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that the query might get stuck when terminated because the memory usage exceeds the limit set by `tidb_mem_quota_query` [#55042](https://github.com/pingcap/tidb/issues/55042) @[yibin87](https://github.com/yibin87) + - Fix the issue that the disk spill for the HashAgg operator causes incorrect query results during parallel calculation [#55290](https://github.com/pingcap/tidb/issues/55290) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue of wrong `JSON_TYPE` when casting `YEAR` to JSON format [#54494](https://github.com/pingcap/tidb/issues/54494) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the value range of the `tidb_schema_cache_size` system variable is wrong [#54034](https://github.com/pingcap/tidb/issues/54034) @[lilinghai](https://github.com/lilinghai) + - Fix the issue that partition pruning does not work when the partition expression is `EXTRACT(YEAR FROM col)` [#54210](https://github.com/pingcap/tidb/issues/54210) @[mjonss](https://github.com/mjonss) + - Fix the issue that `FLASHBACK DATABASE` fails when many tables exist in the database [#54415](https://github.com/pingcap/tidb/issues/54415) @[lance6716](https://github.com/lance6716) + - Fix the issue that `FLASHBACK DATABASE` enters an infinite loop when handling many databases [#54915](https://github.com/pingcap/tidb/issues/54915) @[lance6716](https://github.com/lance6716) + - Fix the issue that adding an index in index acceleration mode might fail [#54568](https://github.com/pingcap/tidb/issues/54568) @[lance6716](https://github.com/lance6716) + - Fix the issue that `ADMIN CANCEL DDL JOBS` might cause DDL to fail [#54687](https://github.com/pingcap/tidb/issues/54687) @[lance6716](https://github.com/lance6716) + - Fix the issue that table replication fails when the index length of the table replicated from DM exceeds the maximum length specified by `max-index-length` [#55138](https://github.com/pingcap/tidb/issues/55138) @[lance6716](https://github.com/lance6716) + - Fix the issue that the error `runtime error: index out of range` might occur when executing SQL statements with `tidb_enable_inl_join_inner_multi_pattern` enabled [#54535](https://github.com/pingcap/tidb/issues/54535) @[joechenrh](https://github.com/joechenrh) + - Fix the issue that you cannot exit TiDB using Control+C during the process of initializing statistics [#54589](https://github.com/pingcap/tidb/issues/54589) @[tiancaiamao](https://github.com/tiancaiamao) + - Fix the issue that the `INL_MERGE_JOIN` optimizer hint returns incorrect results by deprecating it [#54064](https://github.com/pingcap/tidb/issues/54064) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that a correlated subquery that contains `WITH ROLLUP` might cause TiDB to panic and return the error `runtime error: index out of range` [#54983](https://github.com/pingcap/tidb/issues/54983) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that predicates cannot be pushed down properly when the filter condition of a SQL query contains virtual columns and the execution condition contains `UnionScan` [#54870](https://github.com/pingcap/tidb/issues/54870) @[qw4990](https://github.com/qw4990) + - Fix the issue that the error `runtime error: invalid memory address or nil pointer dereference` might occur when executing SQL statements with `tidb_enable_inl_join_inner_multi_pattern` enabled [#55169](https://github.com/pingcap/tidb/issues/55169) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that a query statement that contains `UNION` might return incorrect results [#52985](https://github.com/pingcap/tidb/issues/52985) @[XuHuaiyu](https://github.com/XuHuaiyu) + - Fix the issue that the `tot_col_size` column in the `mysql.stats_histograms` table might be a negative number [#55126](https://github.com/pingcap/tidb/issues/55126) @[qw4990](https://github.com/qw4990) + - Fix the issue that `columnEvaluator` cannot identify the column references in the input chunk, which leads to `runtime error: index out of range` when executing SQL statements [#53713](https://github.com/pingcap/tidb/issues/53713) @[AilinKid](https://github.com/AilinKid) + - Fix the issue that `STATS_EXTENDED` becomes a reserved keyword [#39573](https://github.com/pingcap/tidb/issues/39573) @[wddevries](https://github.com/wddevries) + - Fix the issue that when `tidb_low_resolution` is enabled, `select for update` can be executed [#54684](https://github.com/pingcap/tidb/issues/54684) @[cfzjywxk](https://github.com/cfzjywxk) + - Fix the issue that internal SQL queries cannot be displayed in the slow query log when `tidb_redact_log` is enabled [#54190](https://github.com/pingcap/tidb/issues/54190) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that the memory used by transactions might be tracked multiple times [#53984](https://github.com/pingcap/tidb/issues/53984) @[ekexium](https://github.com/ekexium) + - Fix the issue that using `SHOW WARNINGS;` to obtain warnings might cause a panic [#48756](https://github.com/pingcap/tidb/issues/48756) @[xhebox](https://github.com/xhebox) + - Fix the issue that loading index statistics might cause memory leaks [#54022](https://github.com/pingcap/tidb/issues/54022) @[hi-rustin](https://github.com/Rustin170506) + - Fix the issue that the `LENGTH()` condition is unexpectedly removed when the collation is `utf8_bin` or `utf8mb4_bin` [#53730](https://github.com/pingcap/tidb/issues/53730) @[elsa0520](https://github.com/elsa0520) + - Fix the issue that statistics collection does not update the `stats_history` table when encountering duplicate primary keys [#47539](https://github.com/pingcap/tidb/issues/47539) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that recursive CTE queries might result in invalid pointers [#54449](https://github.com/pingcap/tidb/issues/54449) @[hawkingrei](https://github.com/hawkingrei) + - Fix the issue that the Connection Count monitoring metric in Grafana is incorrect when some connections exit before the handshake is complete [#54428](https://github.com/pingcap/tidb/issues/54428) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that the Connection Count of each resource group is incorrect when using TiProxy and resource groups [#54545](https://github.com/pingcap/tidb/issues/54545) @[YangKeao](https://github.com/YangKeao) + - Fix the issue that when queries contain non-correlated subqueries and `LIMIT` clauses, column pruning might be incomplete, resulting in a less optimal plan [#54213](https://github.com/pingcap/tidb/issues/54213) @[qw4990](https://github.com/qw4990) + - Fix the issue of reusing wrong point get plans for `SELECT ... FOR UPDATE` [#54652](https://github.com/pingcap/tidb/issues/54652) @[qw4990](https://github.com/qw4990) + - Fix the issue that the `TIMESTAMPADD()` function goes into an infinite loop when the first argument is `month` and the second argument is negative [#54908](https://github.com/pingcap/tidb/issues/54908) @[xzhangxian1008](https://github.com/xzhangxian1008) + - Fix the issue that internal SQL statements in the slow log are redacted to null by default [#54190](https://github.com/pingcap/tidb/issues/54190) [#52743](https://github.com/pingcap/tidb/issues/52743) [#53264](https://github.com/pingcap/tidb/issues/53264) @[lcwangchao](https://github.com/lcwangchao) + - Fix the issue that `PointGet` execution plans for `_tidb_rowid` can be generated [#54583](https://github.com/pingcap/tidb/issues/54583) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that `SHOW IMPORT JOBS` reports an error `Unknown column 'summary'` after upgrading from v7.1 [#54241](https://github.com/pingcap/tidb/issues/54241) @[tangenta](https://github.com/tangenta) + - Fix the issue that obtaining the column information using `information_schema.columns` returns warning 1356 when a subquery is used as a column definition in a view definition [#54343](https://github.com/pingcap/tidb/issues/54343) @[lance6716](https://github.com/lance6716) + - Fix the issue that RANGE partitioned tables that are not strictly self-incrementing can be created [#54829](https://github.com/pingcap/tidb/issues/54829) @[Defined2014](https://github.com/Defined2014) + - Fix the issue that `INDEX_HASH_JOIN` cannot exit properly when SQL is abnormally interrupted [#54688](https://github.com/pingcap/tidb/issues/54688) @[wshwsh12](https://github.com/wshwsh12) + - Fix the issue that the network partition during adding indexes using the Distributed eXecution Framework (DXF) might cause inconsistent data indexes [#54897](https://github.com/pingcap/tidb/issues/54897) @[tangenta](https://github.com/tangenta) + ++ PD + + - Fix the issue that no error is reported when binding a role to a resource group [#54417](https://github.com/pingcap/tidb/issues/54417) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that a resource group encounters quota limits when requesting tokens for more than 500 ms [#8349](https://github.com/tikv/pd/issues/8349) @[nolouch](https://github.com/nolouch) + - Fix the issue that the time data type in the `INFORMATION_SCHEMA.RUNAWAY_WATCHES` table is incorrect [#54770](https://github.com/pingcap/tidb/issues/54770) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that resource groups could not effectively limit resource usage under high concurrency [#8435](https://github.com/tikv/pd/issues/8435) @[nolouch](https://github.com/nolouch) + - Fix the issue that an incorrect PD API is called when you retrieve table attributes [#55188](https://github.com/pingcap/tidb/issues/55188) @[JmPotato](https://github.com/JmPotato) + - Fix the issue that the scaling progress is displayed incorrectly after the `scheduling` microservice is enabled [#8331](https://github.com/tikv/pd/issues/8331) @[rleungx](https://github.com/rleungx) + - Fix the issue that the encryption manager is not initialized before use [#8384](https://github.com/tikv/pd/issues/8384) @[rleungx](https://github.com/rleungx) + - Fix the issue that some logs are not redacted [#8419](https://github.com/tikv/pd/issues/8419) @[rleungx](https://github.com/rleungx) + - Fix the issue that redirection might panic during the startup of PD microservices [#8406](https://github.com/tikv/pd/issues/8406) @[HuSharp](https://github.com/HuSharp) + - Fix the issue that the `split-merge-interval` configuration item might not take effect when you modify its value repeatedly (such as changing it from `1s` to `1h` and back to `1s`) [#8404](https://github.com/tikv/pd/issues/8404) @[lhy1024](https://github.com/lhy1024) + - Fix the issue that setting `replication.strictly-match-label` to `true` causes TiFlash to fail to start [#8480](https://github.com/tikv/pd/issues/8480) @[rleungx](https://github.com/rleungx) + - Fix the issue that fetching TSO is slow when analyzing large partitioned tables, causing `ANALYZE` performance degradation [#8500](https://github.com/tikv/pd/issues/8500) @[rleungx](https://github.com/rleungx) + - Fix the potential data races in large clusters [#8386](https://github.com/tikv/pd/issues/8386) @[rleungx](https://github.com/rleungx) + - Fix the issue that when determining whether queries are Runaway Queries, TiDB only counts time consumption spent on the Coprocessor side while missing time consumption spent on the TiDB side, resulting in some queries not being identified as Runaway Queries [#51325](https://github.com/pingcap/tidb/issues/51325) @[HuSharp](https://github.com/HuSharp) + ++ TiFlash + + - Fix the issue that when using the `CAST()` function to convert a string to a datetime with a time zone or invalid characters, the result is incorrect [#8754](https://github.com/pingcap/tiflash/issues/8754) @[solotzg](https://github.com/solotzg) + - Fix the issue that TiFlash might panic after executing `RENAME TABLE ... TO ...` on a partitioned table with empty partitions across databases [#9132](https://github.com/pingcap/tiflash/issues/9132) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that some queries might report a column type mismatch error after late materialization is enabled [#9175](https://github.com/pingcap/tiflash/issues/9175) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that queries with virtual generated columns might return incorrect results after late materialization is enabled [#9188](https://github.com/pingcap/tiflash/issues/9188) @[JinheLin](https://github.com/JinheLin) + - Fix the issue that setting the SSL certificate configuration to an empty string in TiFlash incorrectly enables TLS and causes TiFlash to fail to start [#9235](https://github.com/pingcap/tiflash/issues/9235) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that TiFlash might panic when a database is deleted shortly after creation [#9266](https://github.com/pingcap/tiflash/issues/9266) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that a network partition (network disconnection) between TiFlash and any PD might cause read request timeout errors [#9243](https://github.com/pingcap/tiflash/issues/9243) @[Lloyd-Pottiger](https://github.com/Lloyd-Pottiger) + - Fix the issue that TiFlash write nodes might fail to restart in the disaggregated storage and compute architecture [#9282](https://github.com/pingcap/tiflash/issues/9282) @[JaySon-Huang](https://github.com/JaySon-Huang) + - Fix the issue that read snapshots of TiFlash write nodes are not released in a timely manner in the disaggregated storage and compute architecture [#9298](https://github.com/pingcap/tiflash/issues/9298) @[JinheLin](https://github.com/JinheLin) + ++ TiKV + + - Fix the issue that cleaning up stale regions might accidentally delete valid data [#17258](https://github.com/tikv/tikv/issues/17258) @[hbisheng](https://github.com/hbisheng) + - Fix the issue that `Ingestion picked level` and `Compaction Job Size(files)` are displayed incorrectly in the TiKV dashboard in Grafana [#15990](https://github.com/tikv/tikv/issues/15990) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that `cancel_generating_snap` incorrectly updating `snap_tried_cnt` causes TiKV to panic [#17226](https://github.com/tikv/tikv/issues/17226) @[hbisheng](https://github.com/hbisheng) + - Fix the issue that the information of `Ingest SST duration seconds` is incorrect [#17239](https://github.com/tikv/tikv/issues/17239) @[LykxSassinator](https://github.com/LykxSassinator) + - Fix the issue that CPU profiling flag is not reset correctly when an error occurs [#17234](https://github.com/tikv/tikv/issues/17234) @[Connor1996](https://github.com/Connor1996) + - Fix the issue that bloom filters are incompatible between earlier versions (earlier than v7.1) and later versions [#17272](https://github.com/tikv/tikv/issues/17272) @[v01dstar](https://github.com/v01dstar) + ++ Tools + + + Backup & Restore (BR) + + - Fix the issue that DDLs requiring backfilling, such as `ADD INDEX` and `MODIFY COLUMN`, might not be correctly recovered during incremental restore [#54426](https://github.com/pingcap/tidb/issues/54426) @[3pointer](https://github.com/3pointer) + - Fix the issue that the progress is stuck during backup and restore [#54140](https://github.com/pingcap/tidb/issues/54140) @[Leavrth](https://github.com/Leavrth) + - Fix the issue that the checkpoint path of backup and restore is incompatible with some external storage [#55265](https://github.com/pingcap/tidb/issues/55265) @[Leavrth](https://github.com/Leavrth) + + + TiCDC + + - Fix the issue that the processor might get stuck when the downstream Kafka is inaccessible [#11340](https://github.com/pingcap/tiflow/issues/11340) @[asddongmen](https://github.com/asddongmen) + + + TiDB Data Migration (DM) + + - Fix the issue that schema tracker incorrectly handles LIST partition tables, causing DM errors [#11408](https://github.com/pingcap/tiflow/issues/11408) @[lance6716](https://github.com/lance6716) + - Fix the issue that data replication is interrupted when the index length exceeds the default value of `max-index-length` [#11459](https://github.com/pingcap/tiflow/issues/11459) @[michaelmdeng](https://github.com/michaelmdeng) + - Fix the issue that DM cannot handle `FAKE_ROTATE_EVENT` correctly [#11381](https://github.com/pingcap/tiflow/issues/11381) @[lance6716](https://github.com/lance6716) + + + TiDB Lightning + + - Fix the issue that TiDB Lightning outputs a confusing `WARN` log when it fails to obtain the keyspace name [#54232](https://github.com/pingcap/tidb/issues/54232) @[kennytm](https://github.com/kennytm) + - Fix the issue that the TLS configuration of TiDB Lightning affects cluster certificates [#54172](https://github.com/pingcap/tidb/issues/54172) @[ei-sugimoto](https://github.com/ei-sugimoto) + - Fix the issue that transaction conflicts occur during data import using TiDB Lightning [#49826](https://github.com/pingcap/tidb/issues/49826) @[lance6716](https://github.com/lance6716) + - Fix the issue that large checkpoint files cause performance degradation during the import of numerous databases and tables [#55054](https://github.com/pingcap/tidb/issues/55054) @[D3Hunter](https://github.com/D3Hunter) + +## Contributors + +We would like to thank the following contributors from the TiDB community: + +- [ari-e](https://github.com/ari-e) +- [ei-sugimoto](https://github.com/ei-sugimoto) +- [HaoW30](https://github.com/HaoW30) +- [JackL9u](https://github.com/JackL9u) +- [michaelmdeng](https://github.com/michaelmdeng) +- [mittalrishabh](https://github.com/mittalrishabh) +- [qingfeng777](https://github.com/qingfeng777) +- [renovate](https://github.com/apps/renovate) +- [SandeepPadhi](https://github.com/SandeepPadhi) +- [yzhan1](https://github.com/yzhan1) diff --git a/system-variables.md b/system-variables.md index d0374844e5432..ab582201b57ec 100644 --- a/system-variables.md +++ b/system-variables.md @@ -3163,6 +3163,57 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md). - For new clusters of v6.0.0 or later versions, the default value is `FAST`. For existing clusters that upgrade from versions earlier than v6.0.0, the default value is `OFF`. +<<<<<<< HEAD +======= +### tidb_txn_commit_batch_size New in v6.2.0 + +- Scope: GLOBAL +- Persists to cluster: Yes +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No +- Type: Integer +- Default value: `16384` +- Range: `[1, 1073741824]` +- Unit: Bytes + + + +- This variable is used to control the batch size of transaction commit requests that TiDB sends to TiKV. If most of the transactions in the application workload have a large number of write operations, adjusting this variable to a larger value can improve the performance of batch processing. However, if this variable is set to too large a value and exceeds the limit of TiKV's [`raft-entry-max-size`](/tikv-configuration-file.md#raft-entry-max-size), the commits might fail. + + + + + +- This variable is used to control the batch size of transaction commit requests that TiDB sends to TiKV. If most of the transactions in the application workload have a large number of write operations, adjusting this variable to a larger value can improve the performance of batch processing. However, if this variable is set to too large a value and exceeds the limit of TiKV's maximum size of a single log (which is 8 MiB by default), the commits might fail. + + + +### tidb_txn_entry_size_limit New in v7.6.0 + +- Scope: SESSION | GLOBAL +- Persists to cluster: Yes +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No +- Type: Integer +- Default value: `0` +- Range: `[0, 125829120]` +- Unit: Bytes + + + +- This variable is used to dynamically modify the TiDB configuration item [`performance.txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500). It limits the size of a single row of data in TiDB, which is equivalent to the configuration item. The default value of this variable is `0`, which means that TiDB uses the value of the configuration item `txn-entry-size-limit` by default. When this variable is set to a non-zero value, `txn-entry-size-limit` is also set to the same value. + + + + + +- This variable is used to dynamically modify the TiDB configuration item [`performance.txn-entry-size-limit`](https://docs.pingcap.com/tidb/stable/tidb-configuration-file#txn-entry-size-limit-new-in-v4010-and-v500). It limits the size of a single row of data in TiDB, which is equivalent to the configuration item. The default value of this variable is `0`, which means that TiDB uses the value of the configuration item `txn-entry-size-limit` by default. When this variable is set to a non-zero value, `txn-entry-size-limit` is also set to the same value. + + + +> **Note:** +> +> Modifying this variable with the SESSION scope only affects the current user session, not the internal TiDB session. This might lead to transaction failure if the entry size of an internal TiDB transaction exceeds the limit of the configuration item. Therefore, to dynamically increase the limit, it is recommended that you modify the variable with the GLOBAL scope. + +>>>>>>> e65145aa85 (Make the introduced version clear for "txn-entry-size-limit" (#18672)) ### tidb_txn_mode - Scope: SESSION | GLOBAL diff --git a/tidb-configuration-file.md b/tidb-configuration-file.md index 94329a0c24d5d..00ba9697f01a2 100644 --- a/tidb-configuration-file.md +++ b/tidb-configuration-file.md @@ -381,7 +381,7 @@ Configuration items related to performance. - Default value: `5000` - If a transaction does not roll back or commit after the number of statements exceeds `stmt-count-limit`, TiDB returns the `statement count 5001 exceeds the transaction limitation, autocommit = false` error. This configuration takes effect **only** in the retryable optimistic transaction. If you use the pessimistic transaction or have disabled the transaction retry, the number of statements in a transaction is not limited by this configuration. -### `txn-entry-size-limit` New in v5.0 +### `txn-entry-size-limit` New in v4.0.10 and v5.0.0 - The size limit of a single row of data in TiDB. - Default value: `6291456` (in bytes) diff --git a/tidb-limitations.md b/tidb-limitations.md index 5139b9334783f..654a439e70250 100644 --- a/tidb-limitations.md +++ b/tidb-limitations.md @@ -58,7 +58,7 @@ This document describes the common usage limitations of TiDB, including the maxi -You can adjust the size limit via the [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v50) configuration item. +You can adjust the size limit via the [`txn-entry-size-limit`](/tidb-configuration-file.md#txn-entry-size-limit-new-in-v4010-and-v500) configuration item.