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From Nick Jones <nick.jo...@amd.com>
Subject Re: Combiner function
Date Mon, 02 Aug 2010 15:43:13 GMT
Hi Jackob,
A combiner acts a lot like a reduce step but it's executed on the mapper 
with in-memory data.  I've seen a reduction in job execution time by 
adding one.  The one caveat to keep in mind is that it may or may not 
run on a particular map attempt.


On 8/2/2010 10:39 AM, Jackob Carlsson wrote:
> Hi everyone,
> Could anyone please help me to understand the function of combiner?
> Thanks in advance
> Jackob

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