starocean999 opened a new pull request, #65467:
URL: https://github.com/apache/doris/pull/65467
Related PR: #65205
Problem Summary:
PR #65205 refactored the semi/anti join constraint matching in
`LeadingHint#getJoinConstraint()` to support both semi and anti joins and
handle the constrained side correctly. However, it introduced two bugs that
together cause semi/anti joins to be silently downgraded to INNER/CROSS JOIN:
1. When the constrained side (probe side for left semi/anti, or left side for
right semi/anti) partially overlaps a join child but that child contains
extra tables, the new code does `continue` — skipping the constraint
instead of marking the leading hint as UNUSED. Since
`matchedJoinConstraint`
remains null, `computeJoinType()` falls through to INNER_JOIN or
CROSS_JOIN,
silently dropping the semi/anti semantics.
Example SQL triggering this:
```sql
SELECT /*+ leading(a2 a5 { a3 a1 }) */ COUNT(*)
FROM a1 JOIN a2 ON a2.c1 = a2.c1
LEFT SEMI JOIN a3 ON a2.c2 = a2.c1
JOIN a5 ON a2.c2 = a2.c1;
```
2. The conditionJoinType map uses HashMap<Expression, JoinType> with
put(), so when the same Expression appears in both a semi/anti join
condition and an inner join condition, the later inner join overwrites
the semi/anti join type. This disables the isConditionJoinTypeMatched()
safety net that should have caught the fallback from bug 1.
Root cause:
For bug 1: continue on constrained-side violation should be
return Pair.of(null, false) to indicate the constraint is broken, not
silently skipped.
For bug 2: a single-value-per-key map cannot represent that one expression
belongs to multiple join types. Changed to Map<Expression, Set<JoinType>>
using computeIfAbsent(...).add().
### Check List (For Author)
- Test <!-- At least one of them must be included. -->
- [ ] Regression test
- [ ] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- [ ] This is a refactor/code format and no logic has been changed.
- [ ] Previous test can cover this change.
- [ ] No code files have been changed.
- [ ] Other reason <!-- Add your reason? -->
- Behavior changed:
- [ ] No.
- [ ] Yes. <!-- Explain the behavior change -->
- Does this need documentation?
- [ ] No.
- [ ] Yes. <!-- Add document PR link here. eg:
https://github.com/apache/doris-website/pull/1214 -->
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
- [ ] Add branch pick label <!-- Add branch pick label that this PR should
merge into -->
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