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From "Aihua Xu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-12941) Unexpected result when using MIN() on struct with NULL in first field
Date Tue, 09 Feb 2016 16:19:18 GMT

    [ https://issues.apache.org/jira/browse/HIVE-12941?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15139137#comment-15139137
] 

Aihua Xu commented on HIVE-12941:
---------------------------------

The patch in general looks good. I would suggest to use a enum {Min, Max} to treat NULL as
Min or Max in comparison instead of a boolean.





> Unexpected result when using MIN() on struct with NULL in first field
> ---------------------------------------------------------------------
>
>                 Key: HIVE-12941
>                 URL: https://issues.apache.org/jira/browse/HIVE-12941
>             Project: Hive
>          Issue Type: Bug
>          Components: Hive
>    Affects Versions: 1.1.0
>            Reporter: Jan-Erik Hedbom
>            Assignee: Yongzhi Chen
>         Attachments: HIVE-12941.1.patch, HIVE-12941.2.patch
>
>
> Using MIN() on struct with NULL in first field of a row yields NULL as result.
> Example:
> select min(a) FROM (select 1 as a union all select 2 as a union all select cast(null
as int) as a) tmp;
> OK
> _c0
> 1
> As expected. But if we wrap it in a struct:
> select min(a) FROM (select named_struct("field",1) as a union all select named_struct("field",2)
as a union all select named_struct("field",cast(null as int)) as a) tmp;
> OK
> _c0
> NULL
> Using MAX() works as expected for structs.



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