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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 Wed, 08 Jun 2016 19:35:20 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-2965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15321306#comment-15321306
] 

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

I'll add a few tests for these:
* {{SELECT COUNT(pk1), COUNT(DISTINCT pk1) FROM t;}} will not use the optimization.
* {{SELECT COUNT(DISTINCT pk1), COUNT(DISTINCT pk2) FROM t WHERE pk1='foo'}} and {{SELECT
COUNT(DISTINCT pk1), COUNT(DISTINCT (pk1,pk2)) FROM t}} do use the optimization and they return
the correct values for everything I tested. I'll check some more.


> 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
>             Fix For: 4.8.0
>
>         Attachments: 2965-v2.txt, 2965-v3.txt, 2965.txt
>
>
> 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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