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https://issues.apache.org/jira/browse/CALCITE-5639?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17711506#comment-17711506
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Julian Hyde commented on CALCITE-5639:
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It's quite possible that the Javadoc on {{class Strong}} is incorrect. The
class is rather complicated, especially the reasoning about when an expression
is "strong on" a particular input argument. That said, I think the
implementation of the class is strong (pun intended), is well-supported by unit
tests, and we should use the class more in {{RexSimplify}}.
> RexSimplify should remove IS NOT NULL check when LIKE comparison is present
> ---------------------------------------------------------------------------
>
> Key: CALCITE-5639
> URL: https://issues.apache.org/jira/browse/CALCITE-5639
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.34.0
> Reporter: Leonid Chistov
> Assignee: Leonid Chistov
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Consider query like
> {code:java}
> select r_reason_desc from reason
> where r_reason_desc is not null and r_reason_desc like '%child%'
> {code}
> where "r_reason_desc" is a nullable field.
> When RexSimplify::simplifyFilterPredicates is called on that conjunction of
> expressions, expression is not simplified, meaning that redundant "is not
> null" check is not removed.
> In the same time, if query like
> {code:java}
> select r_reason_desc from reason
> where r_reason_desc is not null and r_reason_desc >= 'A'{code}
> is passed to optimizer, redundant "is not null" check is eliminated.
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