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HBase >> mail # user >> hbase map/reduce questions


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Re: hbase map/reduce questions
> if i do a custom input that split the table by 100 rows, can i
> distribute manually each part  on a node   regardless where the data
> is ?

Yes - if you do a custom split, and have sufficient map slots in your
cluster, you can parallelize the map tasks to run on other nodes as
well. But if you are using HBase as the sink / source, these map tasks
will still reach back to the region server node holding that row. So -
if you have all your rows in two nodes, all the map tasks will still
reach out to those two nodes. Depending on what your map tasks are
doing (intensive crunching vs I/O) this may or may not help with what
you are doing.
--Suraj

On Thu, Apr 5, 2012 at 6:44 AM, Arnaud Le-roy <[EMAIL PROTECTED]> wrote:
> yes i know but it's just an exemple we can do the same exemple with
> one billion but effectivelly you could say me in this case the rows
> would be stored on all node.
>
> maybe it's not possible to distributed manually the task through the cluster ?
> and maybe it's not a good idea but  I would like to know in order to
> make the best schema for my data.
>
> Le 5 avril 2012 15:08, Doug Meil <[EMAIL PROTECTED]> a écrit :
>>
>> If you only have 1000 rows, why use MapReduce?
>>
>>
>>
>>
>>
>> On 4/5/12 6:37 AM, "Arnaud Le-roy" <[EMAIL PROTECTED]> wrote:
>>
>>>but do you think that i can change the default behavior ?
>>>
>>>for exemple i have ten nodes in my cluster and my table is stored only
>>>on two nodes this table have 1000 rows.
>>>with the default behavior only two nodes will work for a map/reduce
>>>task., isn't it ?
>>>
>>>if i do a custom input that split the table by 100 rows, can i
>>>distribute manually each part  on a node   regardless where the data
>>>is ?
>>>
>>>Le 5 avril 2012 00:36, Doug Meil <[EMAIL PROTECTED]> a écrit :
>>>>
>>>> The default behavior is that the input splits are where the data is
>>>>stored.
>>>>
>>>>
>>>>
>>>>
>>>> On 4/4/12 5:24 PM, "sdnetwork" <[EMAIL PROTECTED]> wrote:
>>>>
>>>>>ok thanks,
>>>>>
>>>>>but i don't find the information that tell me how the result of the
>>>>>split
>>>>>is
>>>>>distrubuted across the different node of the cluster ?
>>>>>
>>>>>1) randomely ?
>>>>>2) where the data is stored ?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>