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From "Gabriel Reid (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-213) Add sharded join functionality
Date Sat, 08 Jun 2013 07:02:21 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13678696#comment-13678696
] 

Gabriel Reid commented on CRUNCH-213:
-------------------------------------

I've run the integration tests with both hadoop-1 (i.e. default) and hadoop-2, and everything
passes. Looking at the join tests themselves, it appears that there's nothing order-sensitive
there.
                
> Add sharded join functionality
> ------------------------------
>
>                 Key: CRUNCH-213
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-213
>             Project: Crunch
>          Issue Type: New Feature
>            Reporter: Gabriel Reid
>            Assignee: Gabriel Reid
>         Attachments: CRUNCH-213.patch
>
>
> Performing joins where a large proportion of the values on one or both sides of the join
are mapped to a single key can result in poor performance, as one (or a small number) of reducers
end up handling most of the joining work, leaving the rest of the cluster idle.
> Sharded joining should be added to allow splitting up join keys, thereby distributing
values mapped to a single key over multiple reducer partitions.

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