[jira] Updated: (HIVE-2) [Hive] group by over a subquery with a cluster by not optimized

["Ashish Thusoo (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-2?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ashish Thusoo updated HIVE-2:
-----------------------------

    Component/s: Query Processor

> [Hive] group by over a subquery with a cluster by not optimized
> ---------------------------------------------------------------
>
>                 Key: HIVE-2
>                 URL: https://issues.apache.org/jira/browse/HIVE-2
>             Project: Hadoop Hive
>          Issue Type: Bug
>          Components: Query Processor
>            Reporter: Namit Jain
>
> Consider the following
> select x.a, count(x.b) from (select ...... cluster by a) x group by x.a
> Even though the user has specifically asked to cluster by a, the group by will again run 2 map-reduce jobs,
> sorting by a random number and a in that order. So, there will be a total of 3 map-reduce jobs sorting
> by a, random and a respectively - this should be optimized

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