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https://issues.apache.org/jira/browse/PHOENIX-2965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15319776#comment-15319776
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Julian Hyde commented on PHOENIX-2965:
--------------------------------------

Agreed, composite distinct count (and indeed composite count) is not standard. 
But in my opinion it is a very useful extension to the standard. Calcite and 
MySQL do it.

> 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.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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