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https://issues.apache.org/jira/browse/FLINK-5963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15895178#comment-15895178
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ASF GitHub Bot commented on FLINK-5963:
---------------------------------------

GitHub user fhueske opened a pull request:

    https://github.com/apache/flink/pull/3472

    [FLINK-5963] [table] Remove prepare mapper of DataSetAggregate.

    We remove the preparation mapper to 
    - save one operator
    - be able to apply `AggregateFunction.accumulate()` in a 
`GroupCombineFunction` or `MapPartitionFunction` for pre-aggregation or in a 
`GroupReduceFunction` for final aggregation.

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

    $ git pull https://github.com/fhueske/flink tableRmPrepareMap

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

    https://github.com/apache/flink/pull/3472.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 #3472
    
----

----


> Remove preparation mapper of DataSetAggregate
> ---------------------------------------------
>
>                 Key: FLINK-5963
>                 URL: https://issues.apache.org/jira/browse/FLINK-5963
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>    Affects Versions: 1.3.0
>            Reporter: Fabian Hueske
>            Assignee: Fabian Hueske
>            Priority: Minor
>
> With the new UDAGG interface we do not need the preparation mapper anymore. 
> It adds overhead because 
> - it is another operator
> - it prevents to use {{AggregateFunction.accumulate()}} in a combiner or 
> reducer.
> Hence, it should be removed.



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