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From fding hbase <fding.hb...@gmail.com>
Subject Re: Coprocessors on specific servers
Date Thu, 28 Jun 2012 04:36:11 GMT
HTable api document shows:

  <T extends CoprocessorProtocol, R> Map<byte[],R> coprocessorExec(
      Class<T> protocol, byte[] startKey, byte[] endKey, Batch.Call<T,R>
callable)
      throws IOException, Throwable;


startKey && endKey bounds the region of your interest.

On Thu, Jun 28, 2012 at 5:43 AM, Mohammad Tariq <dontariq@gmail.com> wrote:

> Aman, Lars,
>
>              If I already know in advance that a particular region
> holds the data of my interest, then how can I use Coprocessor to
> operate on that region only and not on all the regions of a particular
> table??Thank you.
>
> Regards,
>     Mohammad Tariq
>
>
> On Wed, Jun 27, 2012 at 11:57 PM, Lars George <lars.george@gmail.com>
> wrote:
> > Hi Mohammad,
> >
> > Not sure I follow. :(
> >
> > Coprocessor is not MapReduce. MapReduce already takes care to run your
> code local to the data.
> >
> > Coprocessors can be seen like lightweight Map-only MapReduce job.
> >
> > You need to share a few more details for us to be able to help.
> >
> > Thanks,
> > Lars
> >
> > On Jun 26, 2012, at 7:44 PM, Mohammad Tariq wrote:
> >
> >> Hello Lars,
> >>
> >>        Thank you so much for the quick response.Actually, I want to
> >> run my MapReduce jobs on a region that contains a specific set of
> >> data.
> >>
> >> Regards,
> >>     Mohammad Tariq
> >>
> >>
> >> On Tue, Jun 26, 2012 at 9:18 PM, Lars George <lars.george@gmail.com>
> wrote:
> >>> Hi Mohammad,
> >>>
> >>> The code runs on the server which is opening the region. It sounds to
> me that this is not what you want and that you need to have access to some
> sort of resources only available on one specific server? Because if that is
> not the case, then you are simply using the coprocessors the wrong way IMHO.
> >>>
> >>> Lars
> >>>
> >>> On Jun 26, 2012, at 6:44 PM, Mohammad Tariq wrote:
> >>>
> >>>> Hello list,
> >>>>
> >>>>         Is it possible to use Coprocessors on some specific
> >>>> regionservers instead of a per-region basis??As per my understanding
a
> >>>> coprocessor allows us to run the code directly on each region
> >>>> server.Please correct me if I am wrong.Many thanks.
> >>>>
> >>>> Please correct me if I am wrong.
> >>>> Regards,
> >>>>     Mohammad Tariq
> >>>
> >
>



-- 

Best Regards!

Fei Ding
fding.church@gmail.com

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