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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (PHOENIX-810) [Performance] DISTINCT with a LIMIT
Date Fri, 02 May 2014 04:42:20 GMT

     [ https://issues.apache.org/jira/browse/PHOENIX-810?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

James Taylor resolved PHOENIX-810.
----------------------------------

       Resolution: Fixed
    Fix Version/s: 5.0.0
                   4.0.0
                   3.0.0

> [Performance] DISTINCT with a LIMIT
> -----------------------------------
>
>                 Key: PHOENIX-810
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-810
>             Project: Phoenix
>          Issue Type: Task
>    Affects Versions: 3.0-Release
>            Reporter: Hari Krishna Dara
>             Fix For: 3.0.0, 4.0.0, 5.0.0
>
>
> I noticed that a DISTINCT query (without an ORDER BY) takes the same amount of time whether
there is a LIMIT or not. If we push the LIMIT clause to the server instead of handling it
on the client side, I would think we could gain a big performance improvement. This is probably
the case with GROUP BY as well (untested).
> Even when there is an ORDER BY, there could still be a slight benefit in pushing the
LIMIT down, as long as the ORDER BY itself is also pushed down.



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