fix shuffle join for recursive cte

[iamlinjunhong]

User description

What type of PR is this?

• [ ] API-change
• [ ] BUG
• [ ] Improvement
• [ ] Documentation
• [ ] Feature
• [ ] Test and CI
• [ ] Code Refactoring

Which issue(s) this PR fixes:

issue #https://github.com/matrixorigin/MO-Cloud/issues/5764

What this PR does / why we need it:

fix shuffle join for recursive cte

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PR Type

Bug fix

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Description

• Fix shuffle join logic for recursive CTE queries

• Add proper batch handling for last batch condition

• Include comprehensive test case for recursive CTE with large dataset

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Changes walkthrough 📝

	Relevant files
Bug fix	shuffle.go Fix batch handling in shuffle operations                                  pkg/sql/colexec/shuffle/shuffle.go Fix batch handling logic by adding bat.Last() condition check Resolve merge conflict by removing duplicate import formatting Ensure proper flow control for last batch in shuffle operations +4/-0
Tests	recursive_cte.result Add test results for recursive CTE fix                                      test/distributed/cases/recursive_cte/recursive_cte.result Add test results for new recursive CTE test case Include expected output showing count of 6 for large dataset query +8/-1      recursive_cte.sql Add comprehensive recursive CTE test case                                test/distributed/cases/recursive_cte/recursive_cte.sql Add comprehensive test case with large dataset (1M records) Test recursive CTE with JOIN operations and filtering conditions Include table creation, data insertion, and cleanup operations +6/-1

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⚡ Recommended focus areas for review Merge Conflict The code contains unresolved merge conflict markers that need to be cleaned up before merging. The import section has Git conflict markers that will cause compilation errors. <<<<<<< HEAD "fmt" ======= >>>>>>> 74ada5848 (fix shuffle join for recursive cte) Logic Error The control flow logic appears incorrect. When bat.Last() is true, the function returns immediately without processing the batch, but the return statement seems to be in the wrong conditional block. } else if bat.Last() { return result, nil

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Fix premature return on last batch The control flow is incorrect - when bat.Last() is true, the function returns immediately without processing the batch. This causes the last batch to be skipped entirely, which can lead to data loss in shuffle operations. pkg/sql/colexec/shuffle/shuffle.go [110-112] } else if bat.Last() { - return result, nil -} else if !bat.IsEmpty() { + shuffle.ctr.ending = true + shuffle.ctr.lastForShufflePool = shuffle.ctr.shufflePool.Ending() +} +if !bat.IsEmpty() { [ ] Apply / Chat <!-- /improve --apply_suggestion=0 --> Suggestion importance[1-10]: 10 __ Why: The suggestion correctly identifies a critical bug introduced in the PR. The new logic for bat.Last() causes the function to return prematurely, skipping the processing of the final batch, which would lead to data loss or incorrect results. The proposed fix is correct.	High
	✅ Resolve merge conflict markers Suggestion Impact: The commit directly implemented the suggestion by removing all merge conflict markers (>>>>>> 74ada5848) and removing the fmt import entirely code diff: -<<<<<<< HEAD - "fmt" - -======= ->>>>>>> 74ada5848 (fix shuffle join for recursive cte) There's an unresolved merge conflict in the import section. The conflict markers need to be resolved by either keeping or removing the fmt import based on whether it's actually used in the code. pkg/sql/colexec/shuffle/shuffle.go [19-23] -<<<<<<< HEAD "fmt" -======= ->>>>>>> 74ada5848 (fix shuffle join for recursive cte) - [Suggestion processed] Suggestion importance[1-10]: 10 __ Why: The suggestion correctly identifies unresolved merge conflict markers (<<<<<<<, =======, >>>>>>>) in the import block. This is a critical error that will cause the build to fail, and it must be resolved before the PR can be merged.	High
[ ] Update <!-- /improve_multi --more_suggestions=true -->