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From "Anton Mushin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-4604) Add support for standard deviation/variance
Date Fri, 28 Oct 2016 12:44:58 GMT

    [ https://issues.apache.org/jira/browse/FLINK-4604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15615280#comment-15615280

Anton Mushin commented on FLINK-4604:

I found rootcause

problems occur only in query with SUM, if in query replace SUM to $SUM0 (or any aggregate
function) then query works.
At time execute {{AggregateReduceFunctionsRule#onMatch}} SUM must replace to $SUM0 [here|https://github.com/apache/calcite/blob/0938c7b6d767e3242874d87a30d9112512d9243a/core/src/main/java/org/apache/calcite/rel/rules/AggregateReduceFunctionsRule.java#L338]
But it is not happening because the types in FLINK is nullable. ( in my case)

I do not know how to solve this problem yet, please let me know if you have idea how resolve
this problem.

> 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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