fix: Operator::returns_null_on_null() should include string concat (||)#22458
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Dandandan merged 1 commit intoMay 23, 2026
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Which issue does this PR close?
Operator::returns_null_on_null()incorrectly classifies string concatenation #22457Rationale for this change
Operator::returns_null_on_null()incorrectly claimed that the string concatenation operator (||) treats NULL input as the empty string; it does not. (Note that theconcat()function has the NULL->empty string behavior, but the operator does not.)While we're here, also teach
Operator::negate()thatOperator::RegexMatchandOperator::RegexNotMatchare pairs, and the same for the case-insensitive versions.What changes are included in this PR?
Operator::returns_null_on_null()that||returns NULL on NULL inputsOperator::negate()thatOperator::RegexMatchandOperator::RegexNotMatchare pairs; same for case-insensitive versionsAre these changes tested?
Yes; new tests added.
Are there any user-facing changes?
Yes, but minor: expression simplification, outer join elimination, and other optimizer can take advantage of this to optimize queries a bit more effectively.