planner: fix wrong TopN's ByItem with expression.ScalarFunction when to PushDownTopN (#60822)

[ti-chi-bot]

This is an automated cherry-pick of #60822

What problem does this PR solve?

Issue Number: close #60655

Problem Summary:

In the #40593,

There is a column in topN.ByItems is generated by proj, when topN is pushed down below proj, topN cannot obtain the column from datasource, to fix this, we can check whether topN.ByItems contains a column(with ID=0) generated by proj, if so, proj will prevent the optimizer from pushing topN down.

1. A column with ID=0 indicates that the column cannot be resolved by data source.
2. To determine whether a column is generated by projection, we can check whether the child of proj contains the column.

What changed and how does it work?

If you find that the TopN you can push down cannot actually be pushed down, you should use the original TopN to assemble into a structure of TopN -> Projection, rather than using the processed TopN to assemble.

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.

planner: fix wrong TopN's ByItem with expression.ScalarFunction when to PushDownTopN

修复在 TopN 下推过程中错误生成带表达式的TopN排序项 

[ti-chi-bot]

@hawkingrei This PR has conflicts, I have hold it.
Please resolve them or ask others to resolve them, then comment /unhold to remove the hold label.

[fixdb]

fix the conflict

[hawkingrei]

/unhold

[codecov]

Codecov Report

Attention: Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-7.5@a4ff00a). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #61004   +/-   ##
================================================
  Coverage               ?   72.3042%           
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  Files                  ?       1417           
  Lines                  ?     414663           
  Branches               ?          0           
================================================
  Hits                   ?     299819           
  Misses                 ?      94901           
  Partials               ?      19943           

Flag	Coverage Δ
unit	72.3042% <63.6363%> (?)

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

Components	Coverage Δ
dumpling	52.9400% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.5531% <0.0000%> (?)

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[fixdb]

+1

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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Details

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-07-08 10:02:23.139828674 +0000 UTC m=+1993995.863007655: ☑️ agreed by AilinKid.
• 2025-07-08 23:31:07.491037187 +0000 UTC m=+2042520.214216168: ☑️ agreed by fixdb.

[fixdb]

/retest