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From "Trevor Strohman (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-525) Need raw comparators for hadoop record types
Date Wed, 11 Oct 2006 20:24:39 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-525?page=comments#action_12441544 ] 
            
Trevor Strohman commented on HADOOP-525:
----------------------------------------

I just added three files (TypeBuilder, WordCountType and TypeBuilder-support.tar) to this
issue based on the thread referenced below.  This code comes from my own MapReduce implementation
and is not directly Hadoop-compatible.  The code here handles automatic generation of record
comparators, hash functions, and serialization code.  The serialization code in particular
uses knowledge of object order to compress the output.

Reference: http://mail-archives.apache.org/mod_mbox/lucene-hadoop-user/200610.mbox/%3c452D1CA7.40000@apache.org%3e

> Need raw comparators for hadoop record types
> --------------------------------------------
>
>                 Key: HADOOP-525
>                 URL: http://issues.apache.org/jira/browse/HADOOP-525
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: record
>    Affects Versions: 0.6.0
>            Reporter: Sameer Paranjpye
>         Assigned To: Milind Bhandarkar
>            Priority: Minor
>             Fix For: 0.8.0
>
>         Attachments: TypeBuilder-support.tar, TypeBuilder.java, WordCountType.java
>
>
> Raw comparators are not generated for types that are generated with the Hadoop record
framework. This could have a substantial performance impact when using hadoop record generated
types in Map/Reduce. The record i/o framework should auto-generate raw comparators for types.
> Comparison for hadoop record i/o types is defined to be member wise comparison of objects.
A possible implementation could only deserialize one member from each object at a time, compare
them and either return or move on to the next member if the values are equal.

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