feiniaofeiafei opened a new pull request, #58372:
URL: https://github.com/apache/doris/pull/58372
### What problem does this PR solve?
Issue Number: close #xxx
Related PR: #xxx
Problem Summary:
### Release note
The optimizer cannot derive predicates across multiple LEFT JOINs. For
example, given a filter on the leftmost table in a chain of LEFT JOINs, the
optimizer should be able to derive predicates on the rightmost table, but it
currently fails to do so.
```sql
create table t1(a int, b int);
create table t2(a int, b int);
create table t3(a int, b int);
insert into t1 values(1,2);
insert into t2 values(1,2);
insert into t3 values(1,2);
insert into t3 values(null,2);
explain logical plan
select * from t1 left join t2 on t1.a=t2.a left join t3 on t2.a=t3.a where
t1.a=1;
LogicalResultSink[110] ( outputExprs=[a#0, b#1, a#2, b#3, a#4, b#5] )
+--LogicalProject[109] ( distinct=false, projects=[a#0, b#1, a#2, b#3, a#4,
b#5] )
+--LogicalJoin[108] ( type=LEFT_OUTER_JOIN,
markJoinSlotReference=Optional.empty, hashJoinConjuncts=[(a#2 = a#4)],
otherJoinConjuncts=[], markJoinConjuncts=[] )
|--LogicalProject[105] ( distinct=false, projects=[a#0, b#1, a#2, b#3]
)
| +--LogicalJoin[104] ( type=LEFT_OUTER_JOIN,
markJoinSlotReference=Optional.empty, hashJoinConjuncts=[(a#0 = a#2)],
otherJoinConjuncts=[], markJoinConjuncts=[] )
| |--LogicalFilter[101] ( predicates=(a#0 = 1) )
| | +--LogicalOlapScan ( qualified=internal.maldb.t1,
indexName=<index_not_selected>, selectedIndexId=1764043369852, preAgg=ON,
operativeCol=[a#0], virtualColumns=[] )
| +--LogicalFilter[103] ( predicates=(a#2 = 1) )
| +--LogicalOlapScan ( qualified=internal.maldb.t2,
indexName=<index_not_selected>, selectedIndexId=1764043369875, preAgg=ON,
operativeCol=[a#2], virtualColumns=[] )
+--LogicalOlapScan ( qualified=internal.maldb.t3,
indexName=<index_not_selected>, selectedIndexId=1764043369898, preAgg=ON,
operativeCol=[a#4], virtualColumns=[] )
```
The optimizer should derive t3.a=1 from t1.a=1 and the join conditions, but
it currently doesn't.
The root cause is that the PullUpPredicates rule doesn't properly handle
predicate pull-up from the right side of LEFT JOINs. This PR fixes this by
generating null-tolerant predicates when pulling up from RIGHT JOIN's right
table and strengthening them when possible based on upper-level join conditions.
None
### 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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