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https://issues.apache.org/jira/browse/CALCITE-2469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16596920#comment-16596920
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Julian Hyde commented on CALCITE-2469:
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Reviewing again now.
I'm investigating whether it's worthwhile to add {{simplifyIsNull()}}, similar
to the existing {{simplifyIsNotNull()}}, that will automatically simplify "f(a)
IS NULL" to "a IS NULL" if "f" is strong. NOT is strong - i.e. "NOT x" is null
if any only if "x" is null.
If it works, I plan to add {{simplifyIsNull}} in addition to [~pzw2018]'s patch.
> RexSimplify should not optimize '(not x) is null' to 'x is not null'
> --------------------------------------------------------------------
>
> Key: CALCITE-2469
> URL: https://issues.apache.org/jira/browse/CALCITE-2469
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.17.0
> Reporter: pengzhiwei
> Assignee: Julian Hyde
> Priority: Critical
>
> The RexSimplify will optimize the '(not x) is null' to 'x is not null'.
> However,this is incorrect.It is same to the case '(not x) is not null' .
>
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