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From Susheel Kumar Gadalay <skgada...@gmail.com>
Subject Re: Question about shuffle/merge/sort phrase
Date Mon, 22 Dec 2014 04:50:34 GMT
Sorry, typo

It is the reducer which will pull the mapper o/p as soon as it completes.

On 12/22/14, Susheel Kumar Gadalay <skgadalay@gmail.com> wrote:
> It is the mapper which will push the o/p to the respective reducer as
> soon as it completes.
>
> The no of reducers are known at the beginning itself.
> The mapper as it process the input split, generate the o/p of for each
> reducer (if the mapper o/p key is eligible for the reducer).
> The reducer will wait till the completion of all map tasks to start it
> processing.
>
>
> On 12/22/14, bit1129@163.com <bit1129@163.com> wrote:
>> Could some one help me on this question? thanks.
>>
>>
>>
>> bit1129@163.com
>>
>> 发件人: Todd
>> 发送时间: 2014-12-21 21:59
>> 收件人: user@hadoop.apache.org
>> 主题: Question about shuffle/merge/sort phrase
>> Hi, Hadoopers,
>> I got a question about shuffle/sort/merge phrase related..
>> My understanding is that shuffle is used to transfer the mapper
>> output(key/value pairs) from mapper node to reducer node, and merge
>> phrase
>> is used to merge all the mapper output from all mapper nodes, and sort
>> phrase is used to sort the key/value pair by key,
>> Then my question, whose responsibility is it that brings each key with
>> all
>> its values together (The reducer's input is a key and an iterative
>> values).
>>
>>
>> Thanks.
>>
>

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