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https://issues.apache.org/jira/browse/CALCITE-2449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16988247#comment-16988247
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Rui Wang commented on CALCITE-2449:
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[~vladimirsitnikov]
Is there some work of Jira that I can help with? It seems a big JIRA.
> RexSimplify overhaul
> --------------------
>
> Key: CALCITE-2449
> URL: https://issues.apache.org/jira/browse/CALCITE-2449
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.17.0
> Reporter: Vladimir Sitnikov
> Assignee: Vladimir Sitnikov
> Priority: Major
>
> I would like to update \{{RexSimplify}} as follows:
> 1) Avoid multiple passes over the same expressions. Current logic calls
> "simplify" in multiple places, and it might cause simplification of the same
> tree again and again.
> 2) I would like to rework \{{unknownAsFalse}} into support for \{{IS TRUE}}.
> Current support for \{{unknownAsFalse}} is hard to follow, and it looks like
> IS_TRUE(expr) allows for the same optimizations. In other words,
> "unknownAsFalse" would become a silent adding of IS_TRUE on top of the input
> expression. Then rules like \{{OR(x, y) IS TRUE ==> x IS TRUE or y IS TRUE}}
> would push \{{IS TRUE}} downstream.
> 3) I would like to "reorder" predicates in a defined order (e.g. rewrite
> \{{5=x ==> x=5}} or \{{(x=1 or y=2) and (z=3)}} ==> \{{(z=3) and (x=1 or
> y=2)}}. It looks like adding \{{int nodeCount;}} to \{{RexNode}} would be
> helpful to rank rex nodes.
> 4) There are other bugs identified by expression fuzzer (like {{and(null,
> not(null))}} conversion to true and so on)
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