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Posted to issues@calcite.apache.org by "Zoltan Haindrich (JIRA)" <ji...@apache.org> on 2018/07/02 13:02:00 UTC
[jira] [Commented] (CALCITE-2393) RexSimplify optimization error
for expression 'x is not null and x <> 5'
[ https://issues.apache.org/jira/browse/CALCITE-2393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16529839#comment-16529839 ]
Zoltan Haindrich commented on CALCITE-2393:
-------------------------------------------
I would like to try to convince you that its working correctly:
* any operation involving unknown results in unknown; so: the result of (x<>5) when x is null: is null (unknown)
* if "x is null" then "x<>5 is null" which is false; because of the setting of unknownAsFalse
I know its a little bit confusing sometimes...
> RexSimplify optimization error for expression 'x is not null and x <> 5'
> -------------------------------------------------------------------------
>
> Key: CALCITE-2393
> URL: https://issues.apache.org/jira/browse/CALCITE-2393
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.16.0
> Reporter: pengzhiwei
> Assignee: Julian Hyde
> Priority: Major
> Fix For: 1.17.0
>
>
> After the optimization of RexSimplify,the expression 'x is not null and x <> 5' (x is nullable) is optimized to 'x<> 5' (RexSimplify#unknownAsFalse is true). I think it is not a correct result because when x is null, null<> 5 should return true,while 'x is not null and x <> 5' return false.
> I think the optimization for "is not null" in RexSimplify#simplifyAnd2ForUnknownAsFalse should exclude the case of not-equal operator.
> I really confused with this optimization, can you give some suggestion,thanks!
>
>
>
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