planner: Add variable for no_decorrelate in select list

[terry1purcell]

What problem does this PR solve?

Issue Number: close #51116

Problem Summary:

What changed and how does it work?

Customer requirement to allow decorrelation of subqueries in the select list. Added a variable to control this behavior.

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 @terry1purcell. Thanks for your PR.

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[terry1purcell]

/ok-to-test

[codecov]

Codecov Report

❌ Patch coverage is 84.78261% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.2007%. Comparing base (d75dc0b) to head (d21f9c8).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #63204        +/-   ##
================================================
+ Coverage   72.7831%   73.2007%   +0.4176%     
================================================
  Files          1832       1832                
  Lines        495876     495984       +108     
================================================
+ Hits         360914     363064      +2150     
+ Misses       113039     111030      -2009     
+ Partials      21923      21890        -33     

Flag	Coverage Δ
integration	42.0138% <78.2608%> (?)
unit	72.2609% <84.7826%> (+0.0075%)	⬆️

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

Components	Coverage Δ
dumpling	52.8700% <ø> (ø)
parser	∅ <ø> (∅)
br	46.4989% <ø> (-0.0102%)	⬇️

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[terry1purcell]

/retest-required

[qw4990]

LGTM, but it's better add some test cases for this.

[terry1purcell]

/retest-required

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-09-02 02:00:28.793809659 +0000 UTC m=+837520.671640613: ☑️ agreed by qw4990.
• 2025-09-03 04:30:02.942591814 +0000 UTC m=+932894.820422768: ☑️ agreed by hawkingrei.

[mjonss]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: benmeadowcroft, hawkingrei, qw4990

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 [hawkingrei,qw4990]
• pkg/bindinfo/OWNERS [hawkingrei,qw4990]
• pkg/planner/OWNERS [hawkingrei,qw4990]
• pkg/sessionctx/vardef/OWNERS [benmeadowcroft]
• pkg/sessionctx/variable/OWNERS [benmeadowcroft]

Approvers can indicate their approval by writing /approve in a comment
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[terry1purcell]

/retest-required

[terry1purcell]

/cherry-pick release-8.5

[ti-chi-bot]

@terry1purcell: new pull request created to branch release-8.5: #63541.
But this PR has conflicts, please resolve them!

In response to this:

/cherry-pick release-8.5

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