zabetak commented on a change in pull request #2385:
URL: https://github.com/apache/calcite/pull/2385#discussion_r656989338
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File path: core/src/main/java/org/apache/calcite/tools/RelBuilder.java
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@@ -2422,18 +2422,16 @@ public RelBuilder join(JoinRelType joinType, RexNode
condition,
}
if (correlate) {
final CorrelationId id = Iterables.getOnlyElement(variablesSet);
- if (!RelOptUtil.notContainsCorrelation(left.rel, id, Litmus.IGNORE)) {
- throw new IllegalArgumentException("variable " + id
- + " must not be used by left input to correlation");
- }
// Correlate does not have an ON clause.
switch (joinType) {
case LEFT:
case SEMI:
case ANTI:
// For a LEFT/SEMI/ANTI, predicate must be evaluated first.
stack.push(right);
- filter(condition.accept(new Shifter(left.rel, id, right.rel)));
+ filter(
+ RelOptUtil.correlateLeftShiftRight(getRexBuilder(),
+ left.rel, id, right.rel, condition));
Review comment:
Let's consider for instance the following plans which can be produced
with the code before and after the changes in this PR.
```
LogicalProject(DEPTNO=[$0], EMPNO=[$3])
LogicalCorrelate(correlation=[$cor0], joinType=[left],
requiredColumns=[{0}])
LogicalTableScan(table=[[scott, DEPT]])
LogicalFilter(condition=[=($cor0.DEPTNO, $7)])
LogicalSort(sort0=[$5], dir0=[ASC], fetch=[2])
LogicalTableScan(table=[[scott, EMP]])
LogicalProject(DEPTNO=[$0], EMPNO=[$3])
LogicalJoin(condition=[=($0, $10)], joinType=[left])
LogicalTableScan(table=[[scott, DEPT]])
LogicalSort(sort0=[$5], dir0=[ASC], fetch=[2])
LogicalTableScan(table=[[scott, EMP]])
```
What I would like to make sure is that whatever is under the right side of
the join/correlate+filter does not give different results if we switch from
correlate+filter to join. I need to find some time to think on it a bit more.
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