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https://issues.apache.org/jira/browse/CALCITE-5036?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17934061#comment-17934061
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xiong duan commented on CALCITE-5036:
-------------------------------------
Sorry for causing this inconvenience. Next time, I will create a new ISSUE
record to document such problems.
In the previous PR
[a81cfb2|https://github.com/apache/calcite/commit/a81cfb2ad001589929e190939cf4db928ebac386],
performance issues might arise by executing RexSimplify in
RelMdPredicates#getPredicates to transform a IS NOT DISTINCT FROM b.
Therefore, in the subsequent PR submitted later
[d9363a9|https://github.com/apache/calcite/commit/d9363a952ce2e1905cca62cdee66076424267503],
I removed the RexSimplify method in RelMdPredicates#getPredicates and instead
transformed a IS NOT DISTINCT FROM b in advance by adding
`CoreRules.FILTER_REDUCE_EXPRESSIONS`.
Since `CoreRules.FILTER_REDUCE_EXPRESSIONS` is an existing optimization, no new
optimization was introduced here. It changed the implementation.
> `RelMetadataQuery#getPulledUpPredicates` support to analyze constant key for
> the operator of IS_NOT_DISTINCT_FROM
> -----------------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-5036
> URL: https://issues.apache.org/jira/browse/CALCITE-5036
> Project: Calcite
> Issue Type: Improvement
> Reporter: Xurenhe
> Assignee: Xurenhe
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.31.0
>
> Time Spent: 2h 40m
> Remaining Estimate: 0h
>
> As we know, `IS NOT DISTINCT FROM` is NULL-Safe equal operator.
> The expression of "{*}`a` IS NOT DISTINCT FROM 10{*}" is equal to "{*}(`a` =
> 10) IS TRUE{*}".
> Currently, `RelMetadataQuery#getPulledUpPredicates` could analyze the
> constant from the constant's equal condition in the filter, not support `IS
> NOT DISTINCT FROM`
> {code:java}
> -- sql
> SELECT deptno,
> mgr,
> ename
> FROM emp
> WHERE deptno IS NOT DISTINCT FROM 10{code}
> By the way, `deptno` need be rewritten to the constant project with number of
> 10, when applying the rule of {*}CoreRules#PROJECT_REDUCE_EXPRESSION{*}S
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