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From "Chang Hu" <chan...@cs.umd.edu>
Subject Re: setMapOutputValueClass doesn't work
Date Mon, 24 Mar 2008 22:42:56 GMT
Thanks Doug!  I am able to run the job after removing the setConbiner()
line.  Does it hurt efficiency and how do I add a combiner?

 - Chang

On Mon, Mar 24, 2008 at 6:26 PM, Doug Cutting <cutting@apache.org> wrote:

> Chang Hu wrote:
> > Code below, also attached.  I put this together from the word count
> > example.
>
> The problem is with your combiner.  When a combiner is specified, it
> generates the final map output, since combination is a map-side
> operation.  Your combiner takes <Text,IntWritable> generated by your
> mapper and generates <Text,Text> outputs, which would not be acceptable
> to your reducer, which accepts <Text,IntWritable> inputs.  Does that
> make sense?
>
> Doug
>



-- 
---------------
√úberstehen ist alles.


Chang Hu
Ph.D. student
Computer Science Department
University of Maryland

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