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MapReduce >> mail # user >> question about preserving data locality in MapReduce with Yarn


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Re: question about preserving data locality in MapReduce with Yarn
Hi Sandy, thank you very much for the information. It is good to know that
MapReduce AM considers the block location information. BTW, I am not very
familiar with the concept of splits. Is it specific to MR jobs? If
possible, code location would be very helpful for reference as I am trying
to implement an application master that needs to consider HDFS
data-locality. thx.

r.
On Mon, Oct 28, 2013 at 10:21 PM, Sandy Ryza <[EMAIL PROTECTED]>wrote:

> Hi Ricky,
>
> The input splits contain the locations of the blocks they cover.  The AM
> gets the information from the input splits and submits requests for those
> location.  Each container request spans all the replicas that the block is
> located on.  Are you interested in something more specific?
>
> -Sandy
>
>
> On Mon, Oct 28, 2013 at 7:09 PM, ricky lee <[EMAIL PROTECTED]> wrote:
>
>> Well, I thought an application master can somewhat ask where the data
>> exist to a namenode.... isn't it true? If it does not know where the data
>> reside, does a MapReduce application master specify the resource name as
>> "*" which means data locality might not be preserved at all? thx,
>>
>> r
>>
>
>