statistics: do not load unnecessary index statistics (#54060)

[ti-chi-bot]

This is an automated cherry-pick of #54060

What problem does this PR solve?

Issue Number: close #54022

Problem Summary:

See more at the issue.

A quick summary:
If you have tidb_opt_objective='determine' enabled, it will trigger some async stats load for some tables. If there tables histogram isn't in the system, it would cause some problems when we try to load it.

What changed and how does it work?

Check that the index statistics are really needed before loading them.

If we don't check it here, it will cause some problems if the index statistics don't exist.

Note: We still don't know why the histogram record for the index is missing. There are some possible issues:

1. When users create this table, they may not have created this index yet, so we don't create the record for it automatically. (But if this is the case, I don't why do we have the index in the stats cache information)
2. It may have been accidentally dropped, but I can't find any scenario where we would only drop one index for a table.

What happened in the test case:

1. We create a table and the statsHandle.Update(do.InfoSchema()) will load this table into the stats cache. You can test it by breakpoint here:
   
2. We drop the stats of the stats, it will clean up all system table records for this table.
3. We insert some data and wait for the modfiy_count and the count is not null in the mysql.stats_meta.
4. Try to select some data from this table by ID, it would trigger an async load. Then we get that bug.
   https://github.com/hi-rustin/tidb/blob/648fc6386aa9aabb365baf0912f1e18c4ab74d95/pkg/planner/core/logical_plan_builder.go#L4824
5. So in the test case we check if the index is still in the needed item array after we fix it.

Check List

Tests

• Unit test
• Integration test
• Manual test
• 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.

Fix a memory leak when loading index statistics.
修复加载 index 统计信息可能会造成内存泄漏的问题

[Rustin170506]

/retest

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-06-18 08:57:25.592179631 +0000 UTC m=+105172.077668463: ☑️ agreed by hi-rustin.
• 2024-06-18 10:08:22.874711342 +0000 UTC m=+109429.360200173: ☑️ agreed by qw4990.

[hawkingrei]

/retest

[hawkingrei]

/retest

[Rustin170506]

/retest

[hawkingrei]

/retest

[Rustin170506]

/retest

[ti-chi-bot]

PR needs rebase.

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: qw4990, Rustin170506

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[Rustin170506]

Because it doesn't have tidb_opt_objective, so I removed the test.

[Rustin170506]

/retest

[codecov]

Codecov Report

Attention: Patch coverage is 18.75000% with 13 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-7.1@bda92d4). Learn more about missing BASE report.

Additional details and impacted files

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[Rustin170506]

/retest

[Rustin170506]

/retest