fix: don't infer join predicates for null-aware joins in push_down_filter - #23901
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`push_down_filter` infers equi-key predicates across a join's ON keys and
pushes them to the opposite side. For a null-aware join (the `LeftAnti`
join produced by `NOT IN` with a nullable subquery), an outer predicate on
the left key such as `outer.id > 5` is rewritten to `sub.id > 5` and pushed
onto the right/subquery input. Because the inferred predicate must be
null-rejecting to be pushed, this drops the subquery's NULL rows, which
breaks the three-valued `NOT IN` semantics: a NULL in the subquery key must
reach the join so the result is empty (UNKNOWN for every row).
For example:
CREATE TABLE outer_t(id INT) AS VALUES (3), (7);
CREATE TABLE sub_t(id INT) AS VALUES (NULL);
SELECT id FROM outer_t WHERE id > 5 AND id NOT IN (SELECT id FROM sub_t);
correctly returns no rows, but previously returned `7` because `sub.id > 5`
was inferred onto the subquery, dropping its NULL row.
Skip predicate inference entirely when `join.null_aware` is set. This
mirrors the null-aware guard added to `FilterNullJoinKeys` in apache#23848.
Add a `push_down_filter` regression unit test asserting no predicate is
inferred onto the subquery side of a null-aware `LeftAnti` join, and SLT
coverage for the failing query (including a `prefer_hash_join = false`,
multi-partition variant).
Co-authored-by: Claude Code
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AdamGS
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Jul 25, 2026
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Thanks @AdamGS for review |
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Which issue does this PR close?
Rationale for this change
push_down_filterinfers equi-key predicates across a join's ON keys and pushes them to the opposite side. For a null-aware join (theLeftAntijoin produced byNOT INwith a nullable subquery), an outer predicate on the left key likeouter.id > 5is rewritten tosub.id > 5and pushed onto the subquery input. Since the inferred predicate must be null-rejecting to be pushed, this drops the subquery's NULL rows and breaks the three-valuedNOT INsemantics — a NULL in the subquery key must reach the join so the result is empty.Same class of bug as #23848, in a different rule.
What changes are included in this PR?
infer_join_predicateswhenjoin.null_awareis set (mirrors the fix: Handle null-aware joins correctly inFilterNullJoinKeyswhen its enabled #23848 guard onFilterNullJoinKeys).push_down_filterunit test asserting no predicate is inferred onto the subquery side of a null-awareLeftAntijoin.prefer_hash_join = false/ multi-partition variant.Are these changes tested?
Yes — new unit test (verified it fails without the guard) and SLT cases. The full optimizer lib suite passes.
Are there any user-facing changes?
No, aside from the correctness fix.