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From "Xuefu Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6348) Order by/Sort by in subquery
Date Tue, 06 Jun 2017 02:01:18 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6348?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16037986#comment-16037986
] 

Xuefu Zhang commented on HIVE-6348:
-----------------------------------

[~lirui], I think it's better to remove it from operator tree and the optimization can be
put as one of the optimization rules.

> Order by/Sort by in subquery
> ----------------------------
>
>                 Key: HIVE-6348
>                 URL: https://issues.apache.org/jira/browse/HIVE-6348
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Gunther Hagleitner
>            Assignee: Rui Li
>            Priority: Minor
>              Labels: sub-query
>         Attachments: HIVE-6348.1.patch, HIVE-6348.2.patch
>
>
> select * from (select * from foo order by c asc) bar order by c desc;
> in hive sorts the data set twice. The optimizer should probably remove any order by/sort
by in the sub query unless you use 'limit '. Could even go so far as barring it at the semantic
level.



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