[jira] [Commented] (FLINK-4691) Add group-windows for streaming tables

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4691?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15529423#comment-15529423 ] 

ASF GitHub Bot commented on FLINK-4691:
---------------------------------------

GitHub user twalthr opened a pull request:

    https://github.com/apache/flink/pull/2562

    [FLINK-4691] [table] Add group-windows for streaming tables

    This PR implements Tumble, Slide, Session group-windows for streaming tables as described in FLIP-11. It adds API, validation, logical representation, and runtime components.
    
    Some additional comments:
    
    I have not implemented the 'systemtime' keyword yet as this would cause more problems than it solves. Especially integrating it into the validation layer would be tricky. The resolution of those special fields happens within a WindowAggregate, however, the logical type of a window should already be known at this point. We are mixing logical operators and expressions which is not very nice. Furthermore, what happens in batch environment if 'systemtime' is used? It could also be a existing column but does not have to be one. That is not specified in the FLIP yet.
    
    The aggregations are not very efficient yet. Currently this PR uses window functions that wrap the GroupReduce functions. We have to rework the aggregations first. Maybe we could use `WindowedStream#apply(R, FoldFunction<T,R>, WindowFunction<R,R,K,W>, TypeInformation<R>)` which means that `R` has to be created in the translation phase.
    
    The tests are mainly ITCases yet, we might want to change that to unit tests once we have means (like new test bases) to do that.
    
    The website documentation is missing yet.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/twalthr/flink FLINK-4691

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/flink/pull/2562.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #2562
    
----
commit edbfe00cb0fd7ea8362c90988eb0860eb9ce6078
Author: twalthr <tw...@apache.org>
Date:   2016-08-25T07:19:53Z

    [FLINK-4691] [table] Add group-windows for streaming tables

----


> Add group-windows for streaming tables	
> ---------------------------------------
>
>                 Key: FLINK-4691
>                 URL: https://issues.apache.org/jira/browse/FLINK-4691
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>            Reporter: Timo Walther
>            Assignee: Timo Walther
>
> Add Tumble, Slide, Session group-windows for streaming tables as described in [FLIP-11|https://cwiki.apache.org/confluence/display/FLINK/FLIP-11%3A+Table+API+Stream+Aggregations]. 
> Implementation of group-windows on streaming tables. This includes implementing the API of group-windows, the logical validation for group-windows, and the definition of the “rowtime” and “systemtime” keywords. Group-windows on batch tables won’t be initially supported and will throw an exception.



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