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https://issues.apache.org/jira/browse/FLINK-1045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15101585#comment-15101585
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Fabian Hueske commented on FLINK-1045:
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As per [discussion on the dev mailing
list|http://mail-archives.apache.org/mod_mbox/flink-dev/201601.mbox/%3CCAAdrtT2UETHDt-zYwbrDiZjnzOSJa7hucAufTBBsFeaCpb1WAA%40mail.gmail.com%3E],
we decided to:
- Remove (not deprecate) the {{Combinable}} annotation.
- Remove the default combine implementation of the {{RichGroupReduceFunction}}.
- Use a combiner for all {{GroupReduceFunction}} that implement a combine
interface ({{CombineFunction}} or {{GroupCombineFunction}}).
We did not discuss this, but I think it makes sense to change the name of the
{{GroupReduceOperator.setCombinable()}} method to {{disableCombiner()}}.
This change will require a review of all! {{GroupReduceFunction}}
implementations.
> Remove Combinable Annotation
> ----------------------------
>
> Key: FLINK-1045
> URL: https://issues.apache.org/jira/browse/FLINK-1045
> Project: Flink
> Issue Type: Improvement
> Components: DataSet API
> Reporter: Fabian Hueske
> Priority: Minor
> Labels: api-change, breaking-api
> Fix For: 1.0.0
>
>
> Since the {{combine()}} method was extracted into an interface, we can check
> if a function is combinable by checking if the interface is implemented.
> Hence, the {{Combinable}} annotation could be removed, IMHO.
> However, this would change the API because {{RichGroupReduceFunction}} could
> no longer have a default implementation of {{combine()}} that can be enabled
> by attaching the annotation.
> Right now, the {{Combinable}} annotation is just not necessary as the
> implementation of the interface tells the system everything it needs to know.
> Removing the {{Combinable}} annotation would also make the handling of
> different combinable functions easier. For example a function that implements
> the interfaces {{GroupReduceFunction}} and {{FlatCombineFunction}} does not
> need to attach the annotation.
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