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MapReduce, mail # user - Merge Reducers Outputs


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Re: Merge Reducers Outputs
David Rosenstrauch 2011-07-27, 14:55
On 07/26/2011 06:52 PM, Mohamed Riadh Trad wrote:
> Dear All,
>
> Is it possible to set up a task with multiple reducers and merge reducers outputs into one single file?
>
> Bests,
>
> Trad Mohamed Riadh, M.Sc, Ing.

Not within the map-reduce job, but you can merge it after the job is
done.  At my previous company we used FileUtil.copyMerge() to do this,
and it worked quite well.

See:

http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/fs/FileUtil.html#copyMerge%28org.apache.hadoop.fs.FileSystem,%20org.apache.hadoop.fs.Path,%20org.apache.hadoop.fs.FileSystem,%20org.apache.hadoop.fs.Path,%20boolean,%20org.apache.hadoop.conf.Configuration,%20java.lang.String%29

DR