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https://issues.apache.org/jira/browse/CALCITE-3890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17534632#comment-17534632
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Chunwei Lei commented on CALCITE-3890:
--------------------------------------
{quote}Emp e LEFT JOIN Dept d USING (deptno)
becomes
(SELECT * FROM Emp WHERE deptno IS NOT NULL) LEFT JOIN Dept d USING (deptno)
{quote}
AFAIK, this transformation is wrong. For left/right join, the
non-NULL-generating sides may have null values and they can not be filtered in
advance.
> Derive IS NOT NULL filter for the inputs of inner join
> -------------------------------------------------------
>
> Key: CALCITE-3890
> URL: https://issues.apache.org/jira/browse/CALCITE-3890
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Chunwei Lei
> Assignee: Chunwei Lei
> Priority: Major
> Labels: pull-request-available
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> We can infer IS NOT NULL predicate from join which implies some columns may
> not be null. For instance,
>
> {code:java}
> select * from a join b on a.id = b.id;
> {code}
> we can infer a.id is not null and b.id is not null.
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