[jira] [Created] (FLINK-4604) Add support for standard deviation/variance

[Shang Yuanchun (Jira)]

Timo Walther created FLINK-4604:
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             Summary: 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


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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