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From Mike Spreitzer <mspre...@us.ibm.com>
Subject Stupid questions about combiners in ...hadoop.mapreduce
Date Mon, 23 May 2011 18:32:29 GMT
In general, the Java interfaces say that one invocation of a combiner 
(technically, a Class<? extends Reducer>) can output multiple (key,value) 
pairs.  So:

What happens if one invocation of a combiner outputs more than one value?

What happens if an output key is different from the input key?

What happens if an output value is of a different class than the class of 
the input values?

Thanks,
Mike Spreitzer

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