Bruno Volpato created CALCITE-7816:
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Summary: SEMI join simplification duplicates a singleton left row
Key: CALCITE-7816
URL: https://issues.apache.org/jira/browse/CALCITE-7816
Project: Calcite
Issue Type: Bug
Reporter: Bruno Volpato
A SEMI join must return each matching left row once. With left `VALUES (1)` and
right `VALUES (1), (1)`, the original join returns one row. The left-singleton
simplification rewrites the join as a filter and projection over the right
input, so it returns two rows. The Project-over-Values variant has the same
problem.
Expected: one left row.
Actual: two identical left rows after simplification.
The left-singleton rules should skip SEMI joins. The right-singleton SEMI
optimization is unaffected.
Fix and regression tests: https://github.com/apache/calcite/pull/5241
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