HIVE-29616: Fix incorrect column lineage when multiple subqueries with identical table aliases#6485
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deniskuzZ
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May 29, 2026
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What changes were proposed in this pull request?
lineage column Predicate baseCols
Why are the changes needed?
The logic in ExprProcFactory#findSourceColumn resolves source columns from TopOps by matching table and field aliases. If a match is found, it returns the result directly. This implementation fails in scenarios involving multiple subqueries with identical table aliases (e.g., in a UNION statement). Because the search returns the first match it encounters, it may link to the wrong source column from a different subquery branch, leading to incorrect lineage
Does this PR introduce any user-facing change?
No
How was this patch tested?
mvn test -Pitests -pl itests/qtest -Dtest=TestMiniLlapLocalCliDriver -Dqfile=lineage8.q