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Date: Fri, 7 Jun 2013 20:50:21 +0000 (UTC)
From: "Gabriel Reid (JIRA)" <jira@apache.org>
To: crunch-dev@incubator.apache.org
Message-ID: <JIRA.12651786.1370638138040.87293.1370638221373@arcas>
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Subject: [jira] [Created] (CRUNCH-213) Add sharded join functionality
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Gabriel Reid created CRUNCH-213:
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             Summary: 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


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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