On Mon, May 23, 2011 at 11:32 AM, Mike Spreitzer wrote:
> 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?
The combiner is responsible for maintaining the sort order (and
partitioning) effected prior to th
the same class)?
>
> Even for question 3, I did not exactly see an answer to "what happens" ---
> only a statement that I should not exercise that case.
>
> Thanks,
> Mike
>
>
>
> From:Ted Yu
> To: mapreduce-user@hadoop.apache.org
&
of the same class)?
Even for question 3, I did not exactly see an answer to "what happens" ---
only a statement that I should not exercise that case.
Thanks,
Mike
From: Ted Yu
To: mapreduce-user@hadoop.apache.org
Date: 05/23/2011 03:04 PM
Subject: Re: Stupid quest
Questions 2 and 3 can be answered relatively easily:
Remember, the output of the combiner is going to be consumed by the reducer.
So the output key/vlaue classes of the combiner have to align with the input
key/vlaue classes of the reducer.
On Mon, May 23, 2011 at 11:32 AM, Mike Spreitzer wrote:
In general, the Java interfaces say that one invocation of a combiner
(technically, a Class) 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 o
