[jira] [Closed] (FLINK-3179) Combiner is not injected if Reduce or GroupReduce input is explicitly partitioned

["Fabian Hueske (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-3179?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fabian Hueske closed FLINK-3179.
--------------------------------
       Resolution: Fixed
    Fix Version/s:     (was: 0.10.2)
                       (was: 1.0.0)
                   1.0.1
                   1.1.0

Fixed for 1.0.1 with cd5773ed302cc3c287b00cef6440cc2d740fc469
Fixed for 1.1.0 with 76da442837d8606d8c4c4d8367b29fd79dc5ba35

> Combiner is not injected if Reduce or GroupReduce input is explicitly partitioned
> ---------------------------------------------------------------------------------
>
>                 Key: FLINK-3179
>                 URL: https://issues.apache.org/jira/browse/FLINK-3179
>             Project: Flink
>          Issue Type: Bug
>          Components: Optimizer
>    Affects Versions: 0.10.1
>            Reporter: Fabian Hueske
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Critical
>             Fix For: 1.1.0, 1.0.1
>
>
> The optimizer does not inject a combiner if the input of a Reducer or GroupReducer is explicitly partitioned as in the following example
> {code}
> DataSet<Tuple2<String,Integer>> words = ...
> DataSet<Tuple2<String,Integer>> counts = words
>   .partitionByHash(0)
>   .groupBy(0)
>   .sum(1);
> {code}
> Explicit partitioning can be useful to enforce partitioning on a subset of keys or to use a different partitioning method (custom or range partitioning).
> This issue should be fixed by changing the {{instantiate()}} methods of the {{ReduceProperties}} and {{GroupReduceWithCombineProperties}} classes such that a combine is injected in front of a {{PartitionPlanNode}} if it is the input of a Reduce or GroupReduce operator. This should only happen, if the Reducer is the only successor of the Partition operator.



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