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https://issues.apache.org/jira/browse/CALCITE-3890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17534496#comment-17534496
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Julian Hyde commented on CALCITE-3890:
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The description does not say that the filter is a relational expression, nor
does it say that the filter is before the join rather than after.
I understand why FULL join is not covered, but could you apply the rule to the
non-NULL-generating sides of LEFT and RIGHT join? E.g.
{code}Emp e LEFT JOIN Dept d USING (deptno){code}
becomes
{code}(SELECT * FROM Emp WHERE deptno IS NOT NULL) LEFT JOIN Dept d USING
(deptno){code}
Were you able to use {{Strong}} as I suggested? It should be easy to cover
cases such as
{code}Emp e JOIN Dept d ON e.deptno > d.deptno{code}
or
{code}Emp e JOIN Dept d ON e.deptno + d.deptno < 10{code}
> Derive IS NOT NULL filter from 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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