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Posted to dev@hive.apache.org by "Gopal V (JIRA)" <ji...@apache.org> on 2014/05/15 04:25:25 UTC

[jira] [Commented] (HIVE-7063) Optimize for the Top N within a Group use case

    [ https://issues.apache.org/jira/browse/HIVE-7063?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13998389#comment-13998389 ] 

Gopal V commented on HIVE-7063:
-------------------------------

This would be exceptionally useful - I have seen at least two implementations of TOPN UDAFs for this.

> Optimize for the Top N within a Group use case
> ----------------------------------------------
>
>                 Key: HIVE-7063
>                 URL: https://issues.apache.org/jira/browse/HIVE-7063
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Harish Butani
>            Assignee: Harish Butani
>
> It is common to rank within a Group/Partition and then only return the Top N entries within each Group.
> With Streaming mode for Windowing, we should push the post filter on the rank into the Windowing processing as a Limit expression.



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