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From Le Zhao <lez...@cs.cmu.edu>
Subject Will already sorted Mapper output improve speed of Sort in reducer?
Date Fri, 08 Jan 2010 03:21:16 GMT

Does anybody know whether sorted Mapper output will decrease the Sort in 
the reduce phase?

I'm teaching a class, and am curious to know how much of a difference 
will sorted vs. unsorted mapper output be.  If the merge sort is 
implemented to deal with already sorted input, then I guess it will be 
fast.  Am I right?


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