[jira] [Work started] (HIVE-13942) Correctness of CASE folding in the presence of NULL values

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-13942?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on HIVE-13942 started by Jesus Camacho Rodriguez.
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> Correctness of CASE folding in the presence of NULL values
> ----------------------------------------------------------
>
>                 Key: HIVE-13942
>                 URL: https://issues.apache.org/jira/browse/HIVE-13942
>             Project: Hive
>          Issue Type: Sub-task
>          Components: CBO
>    Affects Versions: 2.2.0, 2.1.1
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>
> Introduced in HIVE-13068.
> {{(case when key<'90' then 2 else 4 end) > 3}} should not fold to {{key >= '90'}}, as these two expressions are not equivalent for _null_ values. Instead, it should fold to {{not NVL((key < '90'),false)}}.
> This is caused by 1) some methods still calling original _RexUtil.simplify_ method, and 2) further improvements needed in _HiveRexUtil.simplify_.



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