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Date: Wed, 10 Sep 2008 11:15:45 -0700 (PDT)
From: "Doug Cutting (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-4143) Support for a "raw" Partitioner
 that partitions based on the serialized key and not record objects
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    [ https://issues.apache.org/jira/browse/HADOOP-4143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12629895#action_12629895 ] 

Doug Cutting commented on HADOOP-4143:
--------------------------------------

> Unfortunately, Partitioner is an interface [ ... ] 

This is a non-issue with HADOOP-1230.  If this feature is needed soon, then we should push harder on that one.

That said, I'm still not clear on the motivation.  Is it performance?  Comparators already provide both raw and cooked comparisons.  If a partitioner is defined in terms of a comparator, it must currently used a cooked comparison, which might be slower.  If this is a performance issue, then we should measure the potential performance improvement with a benchmark before we consider the API change.  Are there non-performance reasons for this change?

> Support for a "raw" Partitioner that partitions based on the serialized key and not record objects
> --------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-4143
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4143
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: mapred
>            Reporter: Chris Douglas
>         Attachments: 4143-0.patch
>
>
> For some partitioners (particularly those using comparators to classify keys), it would be helpful if one could specify a "raw" partitioner that would receive the serialized version of the key rather than the object emitted from the map.

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