roseduan opened a new pull request, #1896: URL: https://github.com/apache/cloudberry/pull/1896
CPhysicalFullMergeJoin::PdsDerive unconditionally returned the outer child's distribution spec whenever it was Universal, ignoring the inner child's real distribution. When the inner child was actually Singleton (gathered to combine with a Universal/empty outer side), the join's output was mislabeled Universal. Universal trivially satisfies a Replicated requirement, so an enclosing per-segment join (e.g. a comma-join with a third relation) skipped the corrective motion this Singleton child needed, nesting a real cross-segment Gather Motion inside a per-segment execution context. The executor's sanity check in ExecInitMotion (nodeMotion.c) caught the inconsistent slice and raised "unexpected gang size: N". Fix by mirroring the already-correct sibling implementations (CPhysicalFullHashJoin::PdsDerive, CPhysicalHashJoin:: PdsDeriveForOuterJoin): propagate the inner child's real distribution instead of blindly returning the outer's. <!-- Thank you for your contribution to Apache Cloudberry (Incubating)! --> Fixes #ISSUE_Number ### What does this PR do? <!-- Brief overview of the changes, including any major features or fixes --> ### Type of Change - [ ] Bug fix (non-breaking change) - [ ] New feature (non-breaking change) - [ ] Breaking change (fix or feature with breaking changes) - [ ] Documentation update ### Breaking Changes <!-- Remove if not applicable. If yes, explain impact and migration path --> ### Test Plan <!-- How did you test these changes? --> - [ ] Unit tests added/updated - [ ] Integration tests added/updated - [ ] Passed `make installcheck` - [ ] Passed `make -C src/test installcheck-cbdb-parallel` ### Impact <!-- Remove sections that don't apply --> **Performance:** <!-- Any performance implications? --> **User-facing changes:** <!-- Any changes visible to users? --> **Dependencies:** <!-- New dependencies or version changes? --> ### Checklist - [ ] Followed [contribution guide](https://cloudberry.apache.org/contribute/code) - [ ] Added/updated documentation - [ ] Reviewed code for security implications - [ ] This PR contains AI-assisted code generation - [ ] Requested review from [cloudberry committers](https://github.com/orgs/apache/teams/cloudberry-committers) ### Additional Context <!-- Any other information that would help reviewers? Remove if none --> ### CI Skip Instructions <!-- To skip CI builds, add the appropriate CI skip identifier to your PR title. The identifier must: - Be in square brackets [] - Include the word "ci" and either "skip" or "no" - Only use for documentation-only changes or when absolutely necessary --> --- <!-- Join our community: - Mailing list: [[email protected]](https://lists.apache.org/[email protected]) (subscribe: [email protected]) - Discussions: https://github.com/apache/cloudberry/discussions --> -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
