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https://issues.apache.org/jira/browse/CALCITE-7758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18110024#comment-18110024
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Ruben Q L commented on CALCITE-7758:
------------------------------------
Perhaps the title is a bit ambiguous. The idea would be removing existing (but
redundant) IS NOT NULL predicates.
IIUC, you'd like an example on a RexCall that can return NULL on non-NULL
arguments, e.g.
{noformat}
IS_NOT_NULL(REGEXP_SUBSTR(myField, '[xw]yz')) AND REGEXP_SUBSTR(myField,
'[xw]yz') || '123' = 'xyz123'
==>
REGEXP_SUBSTR(myField, '[xw]yz') || '123' = 'xyz123'
{noformat}
I think the proposed PR should work on that, I'll add a unit test to verify...
> RexSimplify does not absorb redundant IS NOT NULL on non-input-ref
> sub-expressions in AND simplification
> --------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-7758
> URL: https://issues.apache.org/jira/browse/CALCITE-7758
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Ruben Q L
> Assignee: Ruben Q L
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.43.0
>
>
> The following simplification:
> {noformat}
> IS_NOT_NULL(x) AND (x + 1) < 10
> =>
> (x + 1) < 10
> {noformat}
> is correctly applied on RexSimplify (Unknown=FALSE) for RexInputRef and
> RexFieldAccess (via simplifyAnd2ForUnknownAsFalse).
> However, if the expression X is e.g. a CAST, the simplification does not
> occur:
> {noformat}
> IS_NOT_NULL(CAST(a)) AND (CAST(a) + 1) < 10
> =>
> unchanged; should be: (CAST(a) + 1) < 10
> {noformat}
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