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https://issues.apache.org/jira/browse/CALCITE-3431?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16955705#comment-16955705
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jin xing commented on CALCITE-3431:
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Thanks for comment [~julianhyde]
I updated the Jira title to make it more clear ~
I created this Jira because semi-join is not created for the simple sql in the
Jira description.
Currently SemiJoinRule is mainly used to create semi-join from
sub-query(IN/EXISTS clause). As the discussion on
[https://github.com/apache/calcite/pull/1469], rather than refine SemiJoinRule,
I would prefer to make a change in SqlToRelConverter and have a direct path
from IN/EXISTS to semi- or anti-semi Join
> SemiJoinRule doesn't work when right-hand side is not Aggregate but distinct
> on join keys
> -----------------------------------------------------------------------------------------
>
> Key: CALCITE-3431
> URL: https://issues.apache.org/jira/browse/CALCITE-3431
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: jin xing
> Assignee: jin xing
> Priority: Major
>
> Calcite generate semi-join by SemiJoinRule, which only works on pattern of
> Join(RelNode, Aggregate).
> Take below sql as an example
> {code:java}
> select * from dept
> where exists (
> select * from emp
> where emp.empno = dept.deptno)
> {code}
> If empno is a key column of emp, thus the original plan is as below
> {code:java}
> LogicalProject(DEPTNO=[$0], NAME=[$1])
> LogicalJoin(condition=[=($0, $2)], joinType=[inner])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> LogicalProject(EMPNO=[$0])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> Thus SemiJoinRule cannot support such a pattern
>
>
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