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From Raj K Singh <rajkrrsi...@gmail.com>
Subject Re: Reduce Task Clarification
Date Wed, 14 Aug 2013 09:18:49 GMT
Implement raw comparator for your emitted keys to sort the output at the
reducer.

::::::::::::::::::::::::::::::::::::::::
Raj K Singh
http://www.rajkrrsingh.blogspot.com
Mobile  Tel: +91 (0)9899821370


On Wed, Aug 14, 2013 at 1:21 AM, Sam Garrett <sam@actionx.com> wrote:

> I am working on a MapReduce job where I would like to have the output
> sorted by a LongWritable value. I read the Anatomy of a MapReduce Run in
> the Definitive Guide and it didn't say explicitly whether reduce() gets
> called only once per map output key. If it does get called only once I was
> thinking that I could use this:
> http://hadoop.apache.org/docs/current/api/org/apache/hadoop/mapreduce/Job.html#setSortComparatorClass(java.lang.Class)to
do the sorting.
>
> Thank you for your time.
>
> --
> Sam Garrett
> ActionX, NYC
>

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