[jira] [Commented] (CALCITE-2555) RexSimplify: >=(true, null) could be simplified to null

[Vladimir Sitnikov (JIRA)]

    [ 
https://issues.apache.org/jira/browse/CALCITE-2555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16620254#comment-16620254
 ] 

Vladimir Sitnikov commented on CALCITE-2555:
--------------------------------------------

So what's the risk?
Wrong results here just means there's a bug in RexSimplify.

For instance, 
https://github.com/apache/calcite/blob/7174a4e42bbf6db2a0cfee4d7de718e7cc0cf49c/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L490-L492
 is an apparent bug in simplifyIs2 for {{unknownAsFalse}} case.

it would basically simplify {{IS NULL(null)}} ==since null is simplified to 
false in unknownAsFalse==> {{IS NULL(false)}} ==> {{false}}

So I think {{withUnknownAsFalse(false)}} must be added to the line 490

> RexSimplify: >=(true, null) could be simplified to null
> -------------------------------------------------------
>
>                 Key: CALCITE-2555
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2555
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.17.0
>            Reporter: Vladimir Sitnikov
>            Assignee: Julian Hyde
>            Priority: Major
>              Labels: newbie
>
> {code:java}
> @Test public void simplifyComparisonWithNull() {
>   checkSimplify2(ge(trueLiteral, falseLiteral), "true", "true");
>   checkSimplify2(ge(trueLiteral, nullBool), "null", "false");
>   checkSimplify2(ge(nullBool, nullBool), "null", "false");
> }
> {code}



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