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From Mike Kendall <mkend...@justin.tv>
Subject Re: Combiner phase question
Date Fri, 04 Dec 2009 21:59:30 GMT
are you sure it can be run in the reduce task?  if it does it's still
before the reducer is called though...  so the flow of your data will
still be: data -> mapper(s) -> optional reducer(s) -> reducer(s) ->
output_data



On Fri, Dec 4, 2009 at 1:42 PM, Owen O'Malley <owen.omalley@gmail.com> wrote:
> On Fri, Dec 4, 2009 at 12:32 PM, Raymond Jennings III <raymondjiii@yahoo.com
>> wrote:
>
>> Does the combiner run once per data node or one per map task?  (That it can
>> run multiple times on the same data node after each map task.)  Thanks.
>>
>
> The combiner can run 0, 1, or many times on each data value. It can run in
> both the map task and reduce task.
>
> -- Owen
>

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