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…e#21068) ## Which issue does this PR close? * Closes apache#20492. ## Rationale for this change `HashJoinExec` currently continues polling and consuming the probe side even after the build side has completed with zero rows. For join types whose output is guaranteed to be empty when the build side is empty, this work is unnecessary. In practice, it can trigger large avoidable scans and extra compute despite producing no output. This is especially costly for cases such as INNER, LEFT, LEFT SEMI, LEFT ANTI, LEFT MARK, and RIGHT SEMI joins. This change makes the stream state machine aware of that condition so execution can terminate as soon as the build side is known to be empty and no probe rows are needed to determine the final result. The change also preserves the existing behavior for join types that still require probe-side rows even when the build side is empty, such as RIGHT, FULL, RIGHT ANTI, and RIGHT MARK joins. ## What changes are included in this PR? * Added `JoinType::empty_build_side_produces_empty_result` to centralize logic determining when an empty build side guarantees empty output. * Updated `HashJoinStream` state transitions to: * Skip transitioning to `FetchProbeBatch` when the build side is empty and output is deterministically empty. * Immediately complete the stream in such cases. * Refactored logic in `build_batch_empty_build_side` to reuse the new helper method and simplify match branches. * Ensured probe-side consumption still occurs for join types that require probe rows (e.g., RIGHT, FULL). * Added helper `state_after_build_ready` to unify post-build decision logic. * Introduced reusable helper for constructing hash joins with dynamic filters in tests. ## Are these changes tested? Yes, comprehensive tests have been added: * Verified that probe side is **not consumed** when: * Build side is empty * Join type guarantees empty output * Verified that probe side **is still consumed** when required by join semantics (e.g., RIGHT, FULL joins) * Covered both filtered and non-filtered joins * Added tests ensuring correct behavior with dynamic filters * Added regression test ensuring correct behavior after partition bounds reporting These tests validate both correctness and the intended optimization behavior. ## Are there any user-facing changes? No API changes. However, this introduces a performance optimization: * Queries involving joins with empty build sides may complete significantly faster * Reduced unnecessary IO and compute No behavioral changes in query results. ## LLM-generated code disclosure This PR includes LLM-generated code and comments. All LLM-generated content has been manually reviewed and tested. (cherry picked from commit 6c5e241)
LiaCastaneda
approved these changes
Apr 16, 2026
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Cherry picks apache#21068