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https://issues.apache.org/jira/browse/PHOENIX-2965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15319760#comment-15319760
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Lars Hofhansl edited comment on PHOENIX-2965 at 6/8/16 12:19 AM:
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Looking around a bit, it turns out that many SQL databases only support
COUNT(DISTINCT ...) for a single DISTINCT column.
Neither MSSQL nor Oracle seem to support this syntax.
was (Author: lhofhansl):
Looking around a bit, it turns out that many SQL databases only support
COUNT(DISTINCT ...) for a single DISTINCT column.
> 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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