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Posted to common-user@hadoop.apache.org by Mark <st...@gmail.com> on 2010/08/26 04:12:59 UTC

Basic question

  job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);

Does this mean the input to the reducer should be Text/IntWritable or 
the output of the reducer is Text/IntWritable?

What is the inverse of this.. setInputKeyClass/setInputValueClass? Is 
this inferred by the JobInputFormatClass? Would someone mind briefly 
explaining?

Thanks

Re: Basic question

Posted by James Seigel <ja...@tynt.com>.

The output of the reducer is Text/IntWritable. 

To set the "input" to the reducer you set the mapper output classes. 

Cheers
James

Sent from my mobile. Please excuse the typos.

On 2010-08-25, at 8:13 PM, "Mark" <st...@gmail.com> wrote:

>  job.setOutputKeyClass(Text.class);
> job.setOutputValueClass(IntWritable.class);
> 
> Does this mean the input to the reducer should be Text/IntWritable or 
> the output of the reducer is Text/IntWritable?
> 
> What is the inverse of this.. setInputKeyClass/setInputValueClass? Is 
> this inferred by the JobInputFormatClass? Would someone mind briefly 
> explaining?
> 
> Thanks