[jira] [Commented] (CALCITE-2451) RexSimplify: fuse unknownAsFalse and IS TRUE handling

["Zoltan Haindrich (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2451?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16571407#comment-16571407 ] 

Zoltan Haindrich commented on CALCITE-2451:
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I've tried this earlier...with a slightly different goal for calcite-2326 but I wasn't able to finish it; my experiences are:

* I think that rexbuilder shouldn't be running rexsimplify under the hood; only at build time, since simplify may happen multiple times and/or simplify may miss the simplification context...
* I feel that the rexsimplify api is a bit too broad...the many methods makes it hard to change it. so I think Calcite-2338 would be good
* I've a feeling that at some point, we may not be able to do the simplification with acceptable compute times without introducing something which also keeps track what have been done so far.
* there are 2 different kind of logics with more or less the same goals:
** there are the predicates way...what this can't do is "further" simplification
** and in one of the and analyzers there's a lot of things going on - which is limited to and; but its even able to notice a variable with an empty range in one pass
but essentially these two are more or less the same; I stopped  while I was planning to merge these 2....

 



> RexSimplify: fuse unknownAsFalse and IS TRUE handling
> -----------------------------------------------------
>
>                 Key: CALCITE-2451
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2451
>             Project: Calcite
>          Issue Type: Sub-task
>          Components: core
>    Affects Versions: 1.17.0
>            Reporter: Vladimir Sitnikov
>            Assignee: Julian Hyde
>            Priority: Major
>
> It looks like {{unknownAsFalse}} duplicates {{IS_TRUE}} handling.
> In other words, {{withUnknownAsFalse(true). simplfy(expr)}} is more or less comparable to {{simplify(isTrue(expr))}}
> Implementing {{IS_TRUE/IS_FALSE/...}} simplification possibilities might make {{unknownAsFalse}} obsolete.



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