[Exec](colocate) disable colocate group execution in bucket shuffle join#63200
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run buildall |
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TPC-H: Total hot run time: 30942 ms |
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TPC-DS: Total hot run time: 169461 ms |
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FE UT Coverage ReportIncrement line coverage |
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FE Regression Coverage ReportIncrement line coverage |
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run external |
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FE Regression Coverage ReportIncrement line coverage |
zclllyybb
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May 15, 2026
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PR approved by at least one committer and no changes requested. |
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/review |
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Review result: no blocking issues found. The change is focused on avoiding tablet-count-based parallelism when a bucket/colocate scan fragment has exchange children, and the fallback matches the existing base scan parallelism path.
Critical checkpoints:
- Goal/test: The PR goal is to avoid over-parallelizing bucket shuffle join fragments; the code implements this by detecting non-empty exchange child jobs and falling back to the base degree-of-parallelism logic. The added unit test covers both exchange-present and pure colocate/no-exchange paths.
- Scope: The modification is small and localized to UnassignedScanBucketOlapTableJob.degreeOfParallelism, with a focused unit test.
- Concurrency/lifecycle: No new shared mutable state, threads, locks, or lifecycle-sensitive objects are introduced.
- Config/compatibility: No new configuration, persistence, serialization, FE-BE protocol, or storage format compatibility changes are introduced.
- Parallel paths: The affected construction path is the bucket-assigned OLAP scan job used for colocate/bucket-shuffle fragments; the fallback delegates to the existing AbstractUnassignedScanJob behavior.
- Conditional checks: The new condition is simple and documented; existing early exits for unpartitioned/query-cache/one-instance cases continue to mirror the base behavior.
- Test coverage: Targeted FE unit test passed: fe/mvnw -pl fe-core -Dtest=UnassignedScanBucketOlapTableJobTest test -Dskip.doc=true. No regression test was added; given this is planner parallelism behavior, a future explain/regression case could further protect end-to-end behavior, but I do not consider it blocking for this small fix.
- Observability/performance: No additional observability is required. The change reduces unnecessary instance parallelism for exchange-containing fragments.
- Data correctness/transactions: No transaction, visible-version, persistence, or data write path changes.
User focus: No additional user-provided review focus was present.
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What problem does this PR solve?
Issue Number: None
Related PR: #63062
Problem Summary:
Disable colocate-style parallelization for bucket shuffle join fragments. When exchange nodes exist,
UnassignedScanBucketOlapTableJobnow falls back to the base degree-of-parallelism logic instead of using the tablet-based colocate strategy,which avoids over-parallelizing join fragments. The colocate path is still kept for pure colocate scans without exchange nodes.
Release note
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