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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1060) Support explicit shuffling of DataSets
Date Mon, 01 Sep 2014 17:04:20 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1060?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14117564#comment-14117564

ASF GitHub Bot commented on FLINK-1060:

Github user rmetzger commented on the pull request:

    I successfully looked superficially over the code ;)

> Support explicit shuffling of DataSets
> --------------------------------------
>                 Key: FLINK-1060
>                 URL: https://issues.apache.org/jira/browse/FLINK-1060
>             Project: Flink
>          Issue Type: Improvement
>          Components: Java API, Optimizer
>            Reporter: Fabian Hueske
>            Assignee: Fabian Hueske
>            Priority: Minor
> Right now, Flink only shuffles data if it is required by some operation such as Reduce,
Join, or CoGroup. There is no way to explicitly shuffle a data set.
> However, in some situations explicit shuffling would be very helpful including:
> - rebalancing before compute-intensive Map operations
> - balancing, random or hash partitioning before PartitionMap operations (see FLINK-1053)
> - better integration of support for HadoopJobs (see FLINK-838)
> With this issue, I propose to add the following methods to {{DataSet}}
> - {{DataSet.partitionHashBy(int...)}} and {{DataSet.partitionHashBy(KeySelector)}} to
perform an explicit hash partitioning
> - {{DataSet.partitionRandomly()}} to shuffle data completely random
> - {{DataSet.partitionRoundRobin()}} to shuffle data in a round-robin fashion that generates
very even distribution with possible bias due to prior distributions
> The {{DataSet.partitionRoundRobin()}} might not be necessary if we think that random
shuffling balances good enough.

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