table/tables: fix buildListColumnsPruner issue in the list partition (#32621)

[ti-srebot]

cherry-pick #32621 to release-5.2
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/32770

After apply modifications, you can push your change to this PR via:

git push [email protected]:ti-srebot/tidb.git pr/32770:release-5.2-0e4084c02d69

---

What problem does this PR solve?

Issue Number: close #32416

Problem Summary:
This also affects the master. This problem can also occur in the following scenario:

1. Set the new collation configuration item to false and run the SQL statement above (create list partition table).
2. Restart the TiDB and execute the select statement.
   The above scenario is analyzed in detail:

In step 1

In the bootstrap phase, new collation is true
After bootstrap ends, new collation is false.

In step 2

1. In the bootstrap phase, new collation is true. ForListColumnPruning builds the hashMap(generate the partition hash key, by calling EncodeKey) in TableFromMeta
2. After bootstrap ends, new collation is false. The generated partition hash key(by calling EncodeKey) could not be found in the hashMap.

What is changed and how it works?

Instead of creating the hashMap in the TableFromMeta phase( In the bootstrap phase), we create the hashMap on a delayed basis (that is, when a partition needs to be located).
In this way, new_collations_enabled_on_first_bootstrap does not have inconsistency problems.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

1. Set the new_collations_enabled_on_first_bootstrap item to false and run the SQL statements as follows:

set @@session.tidb_enable_list_partition = ON;
set @@tidb_partition_prune_mode = 'dynamic';
drop table if exists github_events;
CREATE TABLE `github_events` (
`id` bigint(20) DEFAULT NULL,
`type` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
PARTITION BY LIST COLUMNS(`type`)
(PARTITION `push_event` VALUES IN ("PushEvent"),
PARTITION `watch_event` VALUES IN ("WatchEvent")
);

2. Restart TiDB with new_collations_enabled_on_first_bootstrap = false and execute the following statements:

tidb> set @@session.tidb_enable_list_partition = ON;
Query OK, 0 rows affected (0.00 sec)

tidb> set @@tidb_partition_prune_mode = 'dynamic';
Query OK, 0 rows affected (0.00 sec)

tidb> desc select id,type from github_events  where  type = 'WatchEvent';
+-------------------------+----------+-----------+-----------------------+-------------------------------------------+
| id                      | estRows  | task      | access object         | operator info                             |
+-------------------------+----------+-----------+-----------------------+-------------------------------------------+
| TableReader_7           | 10.00    | root      | partition:watch_event | data:Selection_6                          |
| └─Selection_6           | 10.00    | cop[tikv] |                       | eq(test.github_events.type, "WatchEvent") |
|   └─TableFullScan_5     | 10000.00 | cop[tikv] | table:github_events   | keep order:false, stats:pseudo            |
+-------------------------+----------+-----------+-----------------------+-------------------------------------------+
3 rows in set (0.00 sec)

The above scenario is analyzed in detail:

• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fixed an issue where partition table pruning might not work after server restart (for list partition table)

[ti-chi-bot]

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[ti-srebot]

/run-all-tests

[ti-srebot]

@zimulala you're already a collaborator in bot's repo.

[zimulala]

List partitions are experimental and this issue is not critical, so don't cherry pick