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From Andrew McNabb <amcn...@mcnabbs.org>
Subject Re: [jira] Resolved: (HADOOP-115) Hadoop should allow the user to use SequentialFileOutputformat as the output format and to choose key/value classes that are different from those for map output.
Date Fri, 31 Mar 2006 18:18:48 GMT
On Fri, Mar 31, 2006 at 06:17:48PM +0100, Doug Cutting (JIRA) wrote:
> This is the way it is supposed to work.  From the MapReduce paper:
>   map (k1,v1) ! list(k2,v2)
>   reduce (k2,list(v2)) ! list(v2)
>   I.e., the input keys and values are drawn from a different
>   domain than the output keys and values. Furthermore,
>   the intermediate keys and values are from the same domain
>   as the output keys and values.
> I am closing this bug.  If someone feels strongly that we should extend the MapReduce
model in this direction, then we can re-open it.  But, as it stands, things work as intended.

I agree with you.  If you need to change keys, run a second map-reduce

Andrew McNabb
PGP Fingerprint: 8A17 B57C 6879 1863 DE55  8012 AB4D 6098 8826 6868

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