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https://issues.apache.org/jira/browse/CALCITE-3890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17072391#comment-17072391
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Julian Hyde commented on CALCITE-3890:
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I agree. And we can also push down filters: ‘id is not null’ to both inputs, in
this case.
Hopefully we can use existing logic, e.g. {{class Strong}}, for this deduction.
> Infer IS NOT NULL predicate from join
> -------------------------------------
>
> Key: CALCITE-3890
> URL: https://issues.apache.org/jira/browse/CALCITE-3890
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Chunwei Lei
> Priority: Major
>
> 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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