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https://issues.apache.org/jira/browse/CALCITE-4340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17219777#comment-17219777
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James Starr commented on CALCITE-4340:
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[~danny0405] The bug was introduced in CALCITE-4210.
> Correlated Queries in ON clause do not work when referring to left side
> -----------------------------------------------------------------------
>
> Key: CALCITE-4340
> URL: https://issues.apache.org/jira/browse/CALCITE-4340
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: James Starr
> Priority: Major
> Labels: pull-request-available
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Changes from CALCITE-4210 does not robustly support correlated queries in ON
> clauses.
> For the short term I am going revert the logic for supporting ON clause and
> throw an exception when correlated queries occur in ON clause.
> Then I will follow up with a fix that will support single subqueries in on
> clauses. This will require fixing the offset in Blackboard.register,
> correctly detect if correlated variable is on the being used and adding a
> rule RelDecorrelator joined decorrelations.
> Given:
> {code:sql}
> SELECT *
> FROM dept
> LEFT JOIN bonus ON bonus.job = (
> SELECT emp.job
> FROM emp
> WHERE emp.deptno = dept.deptno
> )
> {code}
> Should generate
> {code}
> LogicalProject(DEPTNO=[$0], NAME=[$1], ENAME=[$2], JOB=[$3], SAL=[$4],
> COMM=[$5])
> LogicalCorrelate(correlation=[$cor0], joinType=[left],
> requiredColumns=[{0}]) //requiring dept.DEPTNO as the correlated value
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> LogicalFilter(condition=[=($1, $4)]) //This is comparing bonus.job =
> emp.job
> LogicalJoin(condition=[true], joinType=[left])
> LogicalTableScan(table=[[CATALOG, SALES, BONUS]])
> LogicalAggregate(group=[{}], agg#0=[SINGLE_VALUE($0)])
> LogicalProject(JOB=[$2])
> LogicalFilter(condition=[=($7, $cor0.DEPTNO)]) //all employees
> for a given department
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> But instead generates:
> {code}
> LogicalProject(DEPTNO=[$0], NAME=[$1], ENAME=[$2], JOB=[$3], SAL=[$4],
> COMM=[$5])
> LogicalJoin(condition=[=($3, $0)], joinType=[left])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> LogicalCorrelate(correlation=[$cor0], joinType=[left],
> requiredColumns=[{0}])
> LogicalTableScan(table=[[CATALOG, SALES, BONUS]])
> LogicalAggregate(group=[{}], agg#0=[SINGLE_VALUE($0)])
> LogicalProject(JOB=[$2])
> LogicalFilter(condition=[=($7, $cor0.DEPTNO)])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
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