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From Jean-Marc Spaggiari <jean-m...@spaggiari.org>
Subject Re: Parallel scan in HBase
Date Fri, 01 Feb 2013 15:29:17 GMT
MR job is almost doing that.

The map methode is called for each row, and you can have multiple jobs
running at the same time.

It's the way the rowcounter is working. Scanning every row to count
it, but spreading the work over all the nodes...

Give it a look.

JM

2013/2/1, Alexander Ignatov <aignatov@mirantis.com>:
> You could use Coprocessors framework. To do that you have to implement
> your own Coprocessors's module and include it to each RegionServers.
>
> Here is an introduction article how to use Coprocessors:
> https://blogs.apache.org/hbase/entry/coprocessor_introduction
>
> --
> Regards,
> Alexander Ignatov
>
>
> On 2/1/2013 6:57 PM, Farrokh Shahriari wrote:
>> Tnx for your reply,
>> In my case, I should scan all rows( about 1 millions to 5 millions rows)
>> in
>> a table & it takes a long time. I wanna know is there any way I can do it
>> in parallel or not ?
>>
>> On Fri, Feb 1, 2013 at 5:32 PM, Mohammad Tariq <dontariq@gmail.com>
>> wrote:
>>
>>> Hello Farrokh,
>>>
>>>      Scans work sequentially with one region after the other. Scans from
>>> client side do not go to regionservers in parallel. And, for the second
>>> question, the code will run at the client side.
>>>
>>> Warm Regards,
>>> Tariq
>>> https://mtariq.jux.com/
>>> cloudfront.blogspot.com
>>>
>>>
>>> On Fri, Feb 1, 2013 at 7:22 PM, Farrokh Shahriari <
>>> mohandes.zebeleh.67@gmail.com> wrote:
>>>
>>>> Hi there
>>>> I have two question about scan in Hbase :
>>>> 1) Does scan operation with specific filter run in parallel on
>>>> different
>>>> regionservers ?
>>>> 2) I wanna know whether this code runs at client side for searching the
>>>> retrieved results or not ?
>>>>
>>>>           for (Result result : scanner1) {
>>>>                           for (KeyValue kv : result.raw()) {
>>>>                           //
>>>>                           // some coeds
>>>>                           //
>>>>                       }
>>>>                 }
>>>>
>>>>
>>>> Farrokh Shahriari
>>>>
>
>
>

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