planner, sctx: open enhanced index join pattern by default | tidb-test=pr/2395

[winoros]

What problem does this PR solve?

Issue Number: ref #47233

Problem Summary:

What changed and how does it work?

Open the var tidb_enable_inl_join_inner_multi_pattern by default.

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.

默认开启 tidb_enable_inl_join_inner_multi_pattern，扩展 TiDB Index Join 的能力
open the variable `tidb_enable_inl_join_inner_multi_pattern` by default, enhancing the power of TiDB's index join.

[winoros]

The extra changes in https://github.com/pingcap/tidb/pull/56172/files#diff-e82acde450b380d2b2347aeb83d34bffaaa10b19d9eb24ea7aadbef96d71c875 is to solve the following issue:

• When there are virtual columns, there'll be projection.
  
• But union scan cannot support projection as its inner child
  
• UnionScan's Attach2Task deals with this case.
  

So I changed the code to solve this issue. The affected test is TestIssue53951 when it chooses g2 as the index join's inner child.

[codecov]

Codecov Report

Attention: Patch coverage is 73.91304% with 6 lines in your changes missing coverage. Please review.

Project coverage is 75.9931%. Comparing base (05cff08) to head (c1a1488).
Report is 246 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #56172        +/-   ##
================================================
+ Coverage   73.3233%   75.9931%   +2.6698%     
================================================
  Files          1604       1656        +52     
  Lines        444617     455783     +11166     
================================================
+ Hits         326008     346364     +20356     
+ Misses        98674      87959     -10715     
- Partials      19935      21460      +1525     

Flag	Coverage Δ
integration	52.0440% <65.2173%> (?)
unit	72.6466% <73.9130%> (+0.1299%)	⬆️

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

Components	Coverage Δ
dumpling	52.9478% <ø> (ø)
parser	∅ <ø> (∅)
br	63.0384% <ø> (+17.7615%)	⬆️

[winoros]

/retest

[elsa0520]

LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-20 02:46:06.601823909 +0000 UTC m=+1188436.342247847: ☑️ agreed by hawkingrei.
• 2024-09-20 02:58:18.030409473 +0000 UTC m=+1189167.770833412: ☑️ agreed by elsa0520.

[AilinKid]

@zimulala ptal

[yudongusa]

LGTM

[tangenta]

lgtm for infoschema

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, elsa0520, hawkingrei, Leavrth, tangenta, yudongusa, zimulala

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

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Needs approval from an approver in each of these files:

• OWNERS [AilinKid,Leavrth,elsa0520,hawkingrei,tangenta,zimulala]
• br/OWNERS [Leavrth]
• pkg/infoschema/OWNERS [tangenta]
• pkg/planner/OWNERS [AilinKid,elsa0520,hawkingrei]
• pkg/session/OWNERS [yudongusa]
• pkg/sessionctx/variable/OWNERS [yudongusa]

Approvers can indicate their approval by writing /approve in a comment
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[tiprow]

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

Test name	Commit	Details	Required	Rerun command
fast_test_tiprow	c1a1488	link	true	/test fast_test_tiprow

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[ti-chi-bot]

@winoros: 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/check_dev_2	c1a1488	link	unknown	/test check-dev2
pull-br-integration-test	c1a1488	link	unknown	/test pull-br-integration-test

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[winoros]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #56882.