[jira] [Commented] (CALCITE-4467) Incorrect simplification for 'NaN' value

["Mihai Budiu (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18038436#comment-18038436 ] 

Mihai Budiu commented on CALCITE-4467:
--------------------------------------

no need to reopen an issue to discuss.

but your question is not really related to this issue, so it should be a separate issue

> Incorrect simplification for 'NaN' value
> ----------------------------------------
>
>                 Key: CALCITE-4467
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4467
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Jesús Camacho Rodríguez
>            Assignee: Jesús Camacho Rodríguez
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.27.0
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> {{RexSimplify}} simplifies {{x = x}} to {{null or x is not null}} (similarly <= and >=), and {{x != x}} to {{null and x is null}} (similarly < and >).
> https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L363
> This may not be applicable in some cases. For instance, if the type of x is floating-point, x could be 'NaN'. While some RDBMS consider 'NaN' = 'NaN' (e.g., Postgres), some others consider 'NaN' != 'NaN' following the IEEE 754 standard. For the latest, the rewriting above will result in incorrect results.
> I think we should simply ignore this simplification for floating-point type.



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