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Posted to issues@ignite.apache.org by "Vladimir Ozerov (JIRA)" <ji...@apache.org> on 2019/01/25 12:16:00 UTC

[jira] [Assigned] (IGNITE-8047) SQL: optimize simple COUNT with DISTINCT query.

     [ https://issues.apache.org/jira/browse/IGNITE-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vladimir Ozerov reassigned IGNITE-8047:
---------------------------------------

    Assignee:     (was: Vladimir Ozerov)

> SQL: optimize simple COUNT with DISTINCT query.
> -----------------------------------------------
>
>                 Key: IGNITE-8047
>                 URL: https://issues.apache.org/jira/browse/IGNITE-8047
>             Project: Ignite
>          Issue Type: Improvement
>          Components: sql
>            Reporter: Andrew Mashenkov
>            Priority: Major
>              Labels: performance
>
> {{SELECT COUNT(DISTINCT <expr>) FROM table}} will fetch full data set to reduce node.
> Looks like we can add group by '<expr>'- push down DISTINCT into map query to reduce network pressure.
> See details on nabble [1].
> [1] [http://apache-ignite-users.70518.x6.nabble.com/COUNT-DISTINCT-could-push-down-group-expressions-tt20782.html]



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