planner: don't choose merge join unless there's hint or join key fully matched | tidb-test=pr/2493

[winoros]

What problem does this PR solve?

Issue Number: close #20710

Problem Summary:

What changed and how does it work?

The previous pr only checks that the left keys will be fully covered.
If left keys meet the condition while right keys do not. we can still choose the merge join automatically and put some join key as the other condition.

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

[fixdb]

+1

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.3476%. Comparing base (2fd5d1a) to head (7eed650).
Report is 153 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #59933        +/-   ##
================================================
+ Coverage   72.9169%   73.3476%   +0.4307%     
================================================
  Files          1701       1701                
  Lines        469725     469767        +42     
================================================
+ Hits         342509     344563      +2054     
+ Misses       106094     104076      -2018     
- Partials      21122      21128         +6     

Flag	Coverage Δ
integration	42.7349% <100.0000%> (?)
unit	72.4319% <100.0000%> (+0.0157%)	⬆️

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

Components	Coverage Δ
dumpling	∅ <ø> (∅)
parser	∅ <ø> (∅)
br	46.2489% <ø> (+0.0089%)	⬆️

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[hawkingrei]

/retest

[hawkingrei]

/ok-to-test

[hawkingrei]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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 [fixdb,hawkingrei]
• pkg/planner/OWNERS [fixdb,hawkingrei]

Approvers can indicate their approval by writing /approve in a comment
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-03-05 22:19:05.316281953 +0000 UTC m=+480058.445201689: ☑️ agreed by fixdb.
• 2025-03-06 06:03:41.550215488 +0000 UTC m=+507934.679135232: ☑️ agreed by hawkingrei.

[hawkingrei]

/cherrypick release-7.5-20250306-v7.5.5-1

[ti-chi-bot]

@hawkingrei: new pull request created to branch release-7.5-20250306-v7.5.5-1: #59936.
But this PR has conflicts, please resolve them!

In response to this:

/cherrypick release-7.5-20250306-v7.5.5-1

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 ti-community-infra/tichi repository.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #59970.
But this PR has conflicts, please resolve them!

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #60426.
But this PR has conflicts, please resolve them!

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #60427.
But this PR has conflicts, please resolve them!