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Date: Fri, 17 Jul 2009 15:16:15 -0700 (PDT)
From: "Ashish Thusoo (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Subject: [jira] Commented: (HIVE-647) SORT BY with GROUP ignored without
 LIMIT
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    [ https://issues.apache.org/jira/browse/HIVE-647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12732756#action_12732756 ] 

Ashish Thusoo commented on HIVE-647:
------------------------------------

I think what Bill is saying is that order by DOES NOT use 1 reducer in his tests. That seems to be a bug to me.


> SORT BY with GROUP ignored without LIMIT
> ----------------------------------------
>
>                 Key: HIVE-647
>                 URL: https://issues.apache.org/jira/browse/HIVE-647
>             Project: Hadoop Hive
>          Issue Type: Bug
>          Components: Query Processor
>            Reporter: Bill Graham
>
> For queries with GROUP BY and SORT BY, the sort is not handled properly when a LIMIT is not supplied. If I run the following two queries, the first returns properly sorted results. The second does not.
> SELECT user, SUM(numRequests) AS num FROM MyTable GROUP BY user SORT BY num DESC LIMIT 50;
> SELECT user, SUM(numRequests) AS num FROM MyTable GROUP BY user SORT BY num DESC;
> Explain is different for the two queries as well. The first uses 3 M/R jobs and the second only uses 2, which might be part of the problem.

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