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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-2965) Use DistinctPrefixFilter logic for COUNT(DISTINCT ...) and COUNT(...) GROUP BY
Date Sun, 12 Jun 2016 16:06:20 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-2965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15326503#comment-15326503
] 

Lars Hofhansl commented on PHOENIX-2965:
----------------------------------------

That still flags the above statement as error without the optimization, but won't when optimizing.
I.e.
{{select /*+ RANGE_SCAN */ count(distinct pk1) from pv order by pk1}} would result in an error,
but
{{select count(distinct pk1) from pv order by pk1}} won't.

> Use DistinctPrefixFilter logic for COUNT(DISTINCT ...) and COUNT(...) GROUP BY
> ------------------------------------------------------------------------------
>
>                 Key: PHOENIX-2965
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-2965
>             Project: Phoenix
>          Issue Type: Sub-task
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>             Fix For: 4.8.0
>
>         Attachments: 2965-v10.txt, 2965-v11.txt, 2965-v12.txt, 2965-v2.txt, 2965-v3.txt,
2965-v4.txt, 2965-v5.txt, 2965-v6.txt, 2965-v7.txt, 2965-v8.txt, 2965-v9.txt, 2965.txt, PHOENIX-2965_wip.patch
>
>
> Parent uses skip scanning to optimize DISTINCT and certain GROUP BY operations along
the row key.
> COUNT queries are optimized differently, could be sped up significantly as well.
> [~giacomotaylor], I might need to help into where COUNT(DISTINCT) queries are planned
and optimized.



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