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https://issues.apache.org/jira/browse/FLINK-4604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15554766#comment-15554766
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Timo Walther commented on FLINK-4604:
-------------------------------------

Yes, you are right. We have to make the costs for STDDEV_POP, etc. very high. 
So if one of those aggregation functions is contained, than 
{{planner.getCostFactory.makeInfiniteCost()}}.

> Add support for standard deviation/variance
> -------------------------------------------
>
>                 Key: FLINK-4604
>                 URL: https://issues.apache.org/jira/browse/FLINK-4604
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: Timo Walther
>            Assignee: Anton Mushin
>         Attachments: 1.jpg
>
>
> Calcite's {{AggregateReduceFunctionsRule}} can convert SQL {{AVG, STDDEV_POP, 
> STDDEV_SAMP, VAR_POP, VAR_SAMP}} to sum/count functions. We should add, test 
> and document this rule. 
> If we also want to add this aggregates to Table API is up for discussion.



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