pkg/planner: avoid eliminating max/min over binary literals

[hawkingrei]

What problem does this PR solve?

Issue Number: close #67040

Problem Summary:

MAX/MIN over a binary literal can return different results depending on whether the GROUP BY
column is rewritten as a unique-key aggregation-elimination case. The eliminated path returned 42
with no warning, while the non-eliminated path returned 0 with warning 1292 Truncated incorrect DOUBLE value: '*'.

What changed and how does it work?

• Skip aggregation elimination for MAX/MIN when the argument is a binary literal.
• Add a planner regression case that covers both MAX and MIN for unique-key and plain GROUP BY
  schemas.

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

Summary by CodeRabbit

• Bug Fixes

  • Corrected aggregation function handling for binary literal values to ensure consistent query output.

• Tests

  • Added regression test validating aggregation query behavior with binary literals.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 11186211-94f3-4591-81b6-076a453e16c9

📥 Commits

Reviewing files that changed from the base of the PR and between 682b45d and 558c99b.

📒 Files selected for processing (1)

• pkg/planner/core/issuetest/planner_issue_test.go

🚧 Files skipped from review as they are similar to previous changes (1)

• pkg/planner/core/issuetest/planner_issue_test.go

---

📝 Walkthrough

Walkthrough

This PR addresses a regression where ABS(MAX(b'101010')) with GROUP BY produced inconsistent results depending on column constraints. The fix adds a regression test and modifies the aggregation elimination rule to prevent rewriting MAX/MIN expressions with binary literal arguments.

Changes

Cohort / File(s)	Summary
Test case for binary literal aggregation regression pkg/planner/core/issuetest/planner_issue_test.go	Adds test case abs-max-binary-literal-group-by-unique-key that verifies ABS(MAX(b'101010')) with GROUP BY produces consistent results (0 rows with warning) regardless of column constraints (ZEROFILL NOT NULL UNIQUE).
Aggregation elimination rule update pkg/planner/core/rule_aggregation_elimination.go	Modified rewriteExpr to skip aggregation elimination rewriting for MAX/MIN when the first argument is a binary literal; non-binary-literal arguments continue to be rewritten via wrapCastFunction.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Suggested labels

release-note, size/M

Suggested reviewers

• qw4990
• AilinKid

Poem

🐰 A binary hop through MAX and MIN,
Where literals once led us to sin,
Now ZEROFILL won't confuse,
Constraints no longer abuse,
Aggregation flows true—we all win! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: preventing aggregation elimination for MAX/MIN over binary literals in the planner.
Linked Issues check	✅ Passed	The PR successfully addresses issue #67040 by preventing aggregation elimination for MAX/MIN with binary literal arguments, ensuring consistent results across different GROUP BY schemas.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the MAX/MIN aggregation elimination bug: test case regression, planner logic update, and helper utilities.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

Tools execution failed with the following error:

Failed to run tools: 13 INTERNAL: Received RST_STREAM with code 2 (Internal server error)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.0335%. Comparing base (25eacc4) to head (558c99b).
⚠️ Report is 13 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #67394        +/-   ##
================================================
+ Coverage   77.7922%   79.0335%   +1.2413%     
================================================
  Files          2023       1960        -63     
  Lines        556481     547051      -9430     
================================================
- Hits         432899     432354       -545     
+ Misses       121834     113664      -8170     
+ Partials       1748       1033       -715     

Flag	Coverage Δ
integration	45.0236% <62.5000%> (-3.1035%)	⬇️
unit	77.0311% <100.0000%> (+0.6846%)	⬆️

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

Components	Coverage Δ
dumpling	61.5065% <ø> (ø)
parser	∅ <ø> (∅)
br	65.8676% <ø> (+5.0298%)	⬆️

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[hawkingrei]

/retest

[hawkingrei]

@pantheon-bot review

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Review failed due to infrastructure/execution failure after retries. Please re-trigger review.

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, qw4990

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Details

Needs approval from an approver in each of these files:

• pkg/planner/OWNERS [AilinKid,qw4990]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-03-30 06:19:08.34162252 +0000 UTC m=+159553.546982577: ☑️ agreed by qw4990.
• 2026-03-30 06:31:34.583567886 +0000 UTC m=+160299.788927933: ☑️ agreed by AilinKid.

[hawkingrei]

/retest

[ti-chi-bot]

@hawkingrei: 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
pull-unit-test-next-gen	558c99b	link	unknown	/test pull-unit-test-next-gen

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