infoschema: don't display tables in MemDB when query TIDB_HOT_REGIONS (#52180)

[ti-chi-bot]

This is an automated cherry-pick of #52180

What problem does this PR solve?

Issue Number: close #50810

Problem Summary:

What changed and how does it work?

Check List

Tests

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

Create a cluster by tiup playground nightly --db 1 --tiflash 0 --without-monitor and wait a minutes.

Before this patch sometimes the query result will like

mysql> select * from `TIDB_HOT_REGIONS`;
+---------------------+----------+--------------------+------------------+------------+-----------+------+----------------+--------------+------------+
| TABLE_ID            | INDEX_ID | DB_NAME            | TABLE_NAME       | INDEX_NAME | REGION_ID | TYPE | MAX_HOT_DEGREE | REGION_COUNT | FLOW_BYTES |
+---------------------+----------+--------------------+------------------+------------+-----------+------+----------------+--------------+------------+
| 4611686018427387961 |     NULL | INFORMATION_SCHEMA | INSPECTION_RULES | NULL       |        56 | read |             37 |            0 |      30600 |
+---------------------+----------+--------------------+------------------+------------+-----------+------+----------------+--------------+------------+
1 row in set (0.00 sec)

After patch, only get tidb_ddl_job table

mysql> select * from `TIDB_HOT_REGIONS`;
+-----------------+----------+---------+--------------+------------+-----------+------+----------------+--------------+------------+
| TABLE_ID        | INDEX_ID | DB_NAME | TABLE_NAME   | INDEX_NAME | REGION_ID | TYPE | MAX_HOT_DEGREE | REGION_COUNT | FLOW_BYTES |
+-----------------+----------+---------+--------------+------------+-----------+------+----------------+--------------+------------+
| 281474976710654 |     NULL | mysql   | tidb_ddl_job | NULL       |        56 | read |             38 |            0 |      30600 |
+-----------------+----------+---------+--------------+------------+-----------+------+----------------+--------------+------------+
1 row in set (0.00 sec)

• No need to test

  • I checked and no code files have been changed.

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

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Additional details and impacted files

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[YangKeao]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Defined2014, YangKeao

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• OWNERS [Defined2014,YangKeao]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-04-16 03:42:36.763021575 +0000 UTC m=+309575.874068023: ☑️ agreed by Defined2014.
• 2024-04-16 08:53:36.450399987 +0000 UTC m=+328235.561446432: ☑️ agreed by YangKeao.