planner: add new variables for instance plan cache

[qw4990]

What problem does this PR solve?

Issue Number: ref #54057

Problem Summary: planner: add new variables for instance plan cache

What changed and how does it work?

Add three new variables for the instance level plan cache:

1. tidb_enable_instance_plan_cache: whether to enable this feature;
2. tidb_instance_plan_cache_target_mem_size: the target memory limit (or soft mem limit) of the cache;
3. tidb_instance_plan_cache_max_mem_size: the max memory limit (or hard mem limit) of the cache;

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.

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

[tiprow]

Hi @qw4990. Thanks for your PR.

PRs from untrusted users cannot be marked as trusted with /ok-to-test in this repo meaning untrusted PR authors can never trigger tests themselves. Collaborators can still trigger tests on the PR using /test all.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[codecov]

Codecov Report

Attention: Patch coverage is 88.46154% with 6 lines in your changes missing coverage. Please review.

Project coverage is 74.0323%. Comparing base (f3e153a) to head (3048f95).
Report is 5 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #55193        +/-   ##
================================================
- Coverage   74.8430%   74.0323%   -0.8107%     
================================================
  Files          1568       1569         +1     
  Lines        364503     441473     +76970     
================================================
+ Hits         272805     326833     +54028     
- Misses        71976      94292     +22316     
- Partials      19722      20348       +626     

Flag	Coverage Δ
integration	24.9815% <36.0000%> (?)

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

Components	Coverage Δ
dumpling	52.9567% <ø> (-2.2327%)	⬇️
parser	∅ <ø> (∅)
br	54.4383% <ø> (+6.7376%)	⬆️

[easonn7]

/approve

[zimulala]

Do we need to consider using TidbOptInt64? I see that many variables are directly set to the default value when the error occurs, and I wonder whether these two variables are considered to be treated the same.

[qw4990]

Updated. PTAL

[zimulala]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: easonn7, time-and-fate, zimulala

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [time-and-fate,zimulala]
• pkg/domain/OWNERS [zimulala]
• pkg/planner/OWNERS [time-and-fate]
• pkg/sessionctx/variable/OWNERS [easonn7]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-05 10:38:03.585799675 +0000 UTC m=+262013.452898763: ☑️ agreed by time-and-fate.
• 2024-08-06 02:09:12.736736232 +0000 UTC m=+317882.603835315: ☑️ agreed by zimulala.