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https://issues.apache.org/jira/browse/CALCITE-7071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17985889#comment-17985889
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Julian Hyde commented on CALCITE-7071:
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I don’t think this should be done as part of ProjectJoinRemoveRule. There
doesn’t need to be a Project. If the join condition is always FALSE the join
should be replaced by a Project with NULL columns on the NULL-generating side.
If there’s a Project on top, that Project will later be rewritten away.
I wish you wouldn’t file a case and then immediately post a PR. It prevents
design discussions.
> Support replacing JOIN node with its child node when JOIN condition is false
> in ProjectJoinRemoveRule
> -----------------------------------------------------------------------------------------------------
>
> Key: CALCITE-7071
> URL: https://issues.apache.org/jira/browse/CALCITE-7071
> Project: Calcite
> Issue Type: Improvement
> Reporter: Zhen Chen
> Assignee: Zhen Chen
> Priority: Minor
> Labels: pull-request-available
> Fix For: 1.41.0
>
>
> SQL
> {code:java}
> SELECT e.deptno
> FROM sales.emp e
> LEFT JOIN sales.dept d ON e.deptno = d.deptno and e.deptno between 3 and 1
> {code}
> Plan before
> {code:java}
> LogicalProject(DEPTNO=[$7])
> LogicalJoin(condition=[false], joinType=[left])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> {code}
> Plan after
> {code:java}
> LogicalProject(DEPTNO=[$7])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> In ProjectJoinRemoveRule, when the Join condition is false, replace the Join
> with its left child for a left join or its right child for a right join. The
> above is an example of a left join.
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