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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1126) shuffle should use serialization to get comparator
Date Fri, 05 Feb 2010 17:43:28 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12830191#action_12830191

Doug Cutting commented on MAPREDUCE-1126:

Owen, your patch uses a deprecated means to create a serialization that does not work for
all serializations.  As such, it is not a complete patch for this issue.  The intended way
to use the serialization API is for the application to use Map<String,String> metadata.
 This was established by HADOOP-6165 and was the rationale for HADOOP-6420.  The method SerializationBase.getMetadataFromClass
should not be called by the framework, but is a utility for class-based serialization implementations.

> shuffle should use serialization to get comparator
> --------------------------------------------------
>                 Key: MAPREDUCE-1126
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1126
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: task
>            Reporter: Doug Cutting
>            Assignee: Aaron Kimball
>             Fix For: 0.22.0
>         Attachments: m-1126-2.patch, MAPREDUCE-1126.2.patch, MAPREDUCE-1126.3.patch,
MAPREDUCE-1126.4.patch, MAPREDUCE-1126.5.patch, MAPREDUCE-1126.6.patch, MAPREDUCE-1126.patch,
> Currently the key comparator is defined as a Java class.  Instead we should use the Serialization
API to create key comparators.  This would permit, e.g., Avro-based comparators to be used,
permitting efficient sorting of complex data types without having to write a RawComparator
in Java.

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