planner: optimize performance of IndexUsage utilities

[YangKeao]

What problem does this PR solve?

Issue Number: close #51898

Problem Summary:

This PR is trying to optimize the performance of IndexUsage utilities. Previously it costed around 1% CPU and did a lot of allocation. This PR tries to optimize it and get some tiny performance boost.

What changed and how does it work?

1. Add a pool to avoid frequently allocating/de-allocating indexUsage and the internal entries.
2. Avoid using getTblInfoForUsedStatsByPhysicalID, which is very slow because it iterates over all tables.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

I used https://gist.github.com/YangKeao/c02ada99d2602d5e7fb5fb94f0581015 to run a stabler select_random_points benchmark. It gives QPS 59029 and 58393 for the commit before index usage and with index usage enabled.

After patching the index usage commit with this PR, the average QPS goes to 58854. I'm not sure whether there are other spaces to improve the performance (like improving the speed of loading stats).

As a reference: the flamegraph before this PR:

The flamegraph after this PR:

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

[ti-chi-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[tiprow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 74.4752%. Comparing base (9831208) to head (01c0eb3).
Report is 12 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #53195        +/-   ##
================================================
+ Coverage   72.4647%   74.4752%   +2.0105%     
================================================
  Files          1492       1492                
  Lines        429133     431318      +2185     
================================================
+ Hits         310970     321225     +10255     
+ Misses        98950      90176      -8774     
- Partials      19213      19917       +704     

Flag	Coverage Δ
integration	49.0293% <71.8750%> (?)
unit	71.2371% <75.0000%> (-0.1203%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	50.2007% <ø> (+8.7605%)	⬆️

[hawkingrei]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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Needs approval from an approver in each of these files:

• OWNERS [hawkingrei,qw4990]
• pkg/planner/OWNERS [hawkingrei,qw4990]
• pkg/statistics/OWNERS [hawkingrei,qw4990]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-13 01:05:15.979633972 +0000 UTC m=+1442469.736769544: ☑️ agreed by hawkingrei.
• 2024-05-13 04:00:03.80272207 +0000 UTC m=+1452957.559857644: ☑️ agreed by qw4990.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.0: #53214.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #53215.