[jira] [Commented] (FLINK-2144) Incremental count, average, and variance for windows

["Aljoscha Krettek (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-2144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15293562#comment-15293562 ] 

Aljoscha Krettek commented on FLINK-2144:
-----------------------------------------

I think this can easily be done by users in a window with a {{FoldFunction}}. Doing it in a generic way as in the aggregation functions on {{WindowedStream}} will never be as fast as a custom implementation.

I would vote to close this issue.

> Incremental count, average, and variance for windows
> ----------------------------------------------------
>
>                 Key: FLINK-2144
>                 URL: https://issues.apache.org/jira/browse/FLINK-2144
>             Project: Flink
>          Issue Type: New Feature
>          Components: Streaming
>            Reporter: Gabor Gevay
>            Priority: Minor
>              Labels: statistics
>
> By count I mean the number of elements in the window.
> These can be implemented very efficiently building on FLINK-2143:
> Store: O(1)
> Evict: O(1)
> emitWindow: O(1)



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