Mailing-List: contact dev-help@crunch.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@crunch.apache.org
Date: Fri, 7 Jun 2013 20:52:20 +0000 (UTC)
From: "Gabriel Reid (JIRA)" <jira@apache.org>
To: crunch-dev@incubator.apache.org
Message-ID: <JIRA.12651786.1370638138040.87309.1370638340893@arcas>
In-Reply-To: <JIRA.12651786.1370638138040@arcas>
References: <JIRA.12651786.1370638138040@arcas>
Subject: [jira] [Updated] (CRUNCH-213) Add sharded join functionality
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


     [ https://issues.apache.org/jira/browse/CRUNCH-213?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gabriel Reid updated CRUNCH-213:
--------------------------------

    Attachment: CRUNCH-213.patch

Patch to introduce sharded joins. The join code is also pretty thoroughly refactored, introducing the concept of a JoinStrategy, with three implementations: DefaultJoinStrategy, MapsideJoinStrategy, and ShardedJoinStrategy.
                
> 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.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira