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HBase >> mail # user >> Coprocessor end point vs MapReduce?

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Re: Coprocessor end point vs MapReduce?
>What I still don’t understand is, since both CP and MR are both
>running on the region side, with is the MR better than the CP?
For the case bulk delete alone CP (Endpoint) will be better than MR for
sure..  Considering your over all need people were suggesting better MR..
U need a scan and move some data into another table too...
Both MR and CP run on the region side ???  - Well there is difference. The
CP run within your RS process itself.. So that is why bulk delete using
Endpoint is efficient..  It is a local read and delete. No n/w calls
involved at all..  But in case of MR even if the mappers run on the same
machine as that of the region it is a inter process communication..
Hope I explained you the diff well...


On Thu, Oct 25, 2012 at 6:31 PM, Jean-Marc Spaggiari <

> Hi all,
> First, sorry about my slowness to reply to this thread, but it went to
> my spam folder and I lost sight of it.
> I don’t have good knowledge of RDBMS, and so I don’t have good
> knowledge of triggers too. That’s why I looked at the endpoints too
> because they are pretty new for me.
> First, I can’t really use multiple tables. I have one process writing
> to this table barely real-time. Another one is deleting from this
> table too. But some rows are never deleted. They are timing out, and
> need to be moved by the process I’m building here.
> I was not aware of the possibility to setup the priority for an MR job
> (any link to show how?). That’s something I will dig into. I was a bit
> scared about the network load if I’m doing deletes lines by lines and
> not bulk.
> What I still don’t understand is, since both CP and MR are both
> running on the region side, with is the MR better than the CP? Because
> the hadoop framework is taking care of it and will guarantee that it
> will run on all the regions?
> Also, is there some sort of “pre” and “post” methods I can override
> for MR jobs to initially list of puts/deletes and submit them at the
> end? Or should I do that one by one on the map method?
> Thanks,
> JM
> 2012/10/18, lohit <[EMAIL PROTECTED]>:
> > I might be little off here. If rows are moved to another table on weekly
> or
> > daily basis, why not create per weekly or per day table.
> > That way you need to copy and delete. Of course it will not work you are
> > are selectively filtering between timestamps and clients have to have
> > notion of multiple tables.
> >
> > 2012/10/18 Anoop Sam John <[EMAIL PROTECTED]>
> >
> >> A CP and Endpoints operates at a region level.. Any operation within one
> >> region we can perform using this..  I have seen in below use case that
> >> along with the delete there was a need for inserting data to some other
> >> table also.. Also this was kind of a periodic action.. I really doubt
> how
> >> the endpoints alone can be used here.. I also tend towards the MR..
> >>
> >>   The idea behind the bulk delete CP is simple.  We have a use case of
> >> deleting a bulk of rows and this need to be online delete. I also have
> >> seen
> >> in the mailing list many people ask question regarding that... In all
> >> people were using scans and get the rowkeys to the client side and then
> >> doing the deletes..  Yes most of the time complaint was the slowness..
> >> One
> >> bulk delete performance improvement was done in HBASE-6284..  Still
> >> thought
> >> we can do all the operation (scan+delete) in server side and we can make
> >> use of the endpoints here.. This will be much more faster and can be
> used
> >> for online bulk deletes..
> >>
> >> -Anoop-
> >>
> >> ________________________________________
> >> From: Michael Segel [[EMAIL PROTECTED]]
> >> Sent: Thursday, October 18, 2012 11:31 PM
> >> Subject: Re: Coprocessor end point vs MapReduce?
> >>
> >> Doug,
> >>
> >> One thing that concerns me is that a lot of folks are gravitating to
> >> Coprocessors and may be using them for the wrong thing.