infoschema_v2: get table cache with old schema version

[GMHDBJD]

What problem does this PR solve?

Issue Number: ref #50959

Problem Summary:

What changed and how does it work?

• set table cache key with the old schema version instead of current schema version, therefore, we only have one table cache when schema version update(DDL not related to that table)

Check List

Tests

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

func init() {
    enableV2.Store(true)
}

Start tidb, create some tabe, insert data, drop table, verify the basic operations etc...

This commit doesn't break anyting because the new code is not used now.
We need prepare a test plan document and add tests later.

• 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 @GMHDBJD. Thanks for your PR.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 11 lines in your changes missing coverage. Please review.

Project coverage is 72.7607%. Comparing base (961159c) to head (16dbe9d).
Report is 2030 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #51385        +/-   ##
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+ Coverage   70.6643%   72.7607%   +2.0964%     
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  Files          1461       1461                
  Lines        434873     436202      +1329     
================================================
+ Hits         307300     317384     +10084     
+ Misses       108320      98857      -9463     
- Partials      19253      19961       +708     

Flag	Coverage Δ
integration	49.0201% <0.0000%> (?)

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Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	51.2288% <ø> (+5.3446%)	⬆️

[GMHDBJD]

/retest

[tiprow]

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[tiancaiamao]

For the btree, we don't need to update it.
applyDiff could maintain one copy of the correct schema version if table does not change.

[GMHDBJD]

I mean if we get a table at v1, after a long time, if the version increase to v100, can we update it in Btree to v100?(if the table does not change)

[tiancaiamao]

Yes, we can, it does not affect the correctness, but it is not always be a positive change.

Depending on our caching strategy:

1. shall we always tend to cache the newest table for every schema change?
2. shall we tend to lazy update the cache, i.e. cache the old table if schema change but a specific table was not touched?
3. shall we tend to cache multiple schema version of a table, even the table meta info do not change?

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-28 09:12:55.592608716 +0000 UTC m=+1039664.340231855: ☑️ agreed by tiancaiamao.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: tiancaiamao
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[GMHDBJD]

/retest

[tiprow]

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[ti-chi-bot]

PR needs rebase.

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[ti-chi-bot]

@GMHDBJD: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/unit-test	16dbe9d	link	true	/test unit-test
pull-br-integration-test	16dbe9d	link	true	/test pull-br-integration-test
pull-lightning-integration-test	16dbe9d	link	true	/test pull-lightning-integration-test
pull-integration-e2e-test	16dbe9d	link	true	/test pull-integration-e2e-test

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