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https://issues.apache.org/jira/browse/FLINK-848?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stephan Ewen resolved FLINK-848.
--------------------------------
Resolution: Fixed
Fix Version/s: (was: pre-apache)
0.7.1-incubating
Has been moved to interfaces {{CombineFunction}} and {{GroupCombineFunction}}
> Move combine() from GroupReduceFunction to Interface
> ----------------------------------------------------
>
> Key: FLINK-848
> URL: https://issues.apache.org/jira/browse/FLINK-848
> Project: Flink
> Issue Type: Sub-task
> Components: Java API
> Reporter: Fabian Hueske
> Assignee: Kostas Tzoumas
> Labels: breaking-api, github-import
> Fix For: 0.7.1-incubating
>
>
> Currently, the combine method of the GroupReduceFunction allows to return
> multiple values using a collector. However, most combiners do not need this
> because they return only a single value. Furthermore, a single value
> returning combiner can be executed using more efficient hash-based strategies.
> Hence, we propose to introduce a combine method for GroupReduce which returns
> only a single value. In order to keep support for the rare cases where more
> than one value needs to be returned, we want to keep the collector-combiner
> as well.
> To do so, we could remove the combine method from the abstract
> GroupReduceFunction class and add two Combinable interfaces, one for a
> single-value and one for a multi-value combiner.
> This would also make the Combinable annotation obsolete as the optimizer can
> check whether a GroupReduceFunction implements one of the Combinable
> interfaces or not.
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/stratosphere/stratosphere/issues/848
> Created by: [fhueske|https://github.com/fhueske]
> Labels: core, enhancement,
> Milestone: Release 0.6 (unplanned)
> Created at: Thu May 22 10:23:04 CEST 2014
> State: open
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