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From: Jean-Marc Spaggiari <jean-marc@spaggiari.org>
Date: Sat, 16 Mar 2013 09:51:12 -0400
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 <CAPQV63VN-sG_ztvKN0atS7-Wnc3v716r9AU4ChLzez724BhPEQ@mail.gmail.com>
Subject: Re: review request: HBASE-7403 Online Merge
To: dev@hbase.apache.org
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I see.

I agree that we should throw a warning at least, when someone is
trying to merge such regions. Might still be good to have this
possibility.

JM

2013/3/16 Kevin O'dell <kevin.odell@cloudera.com>:
> Ted,
>
>   Why would we use that merge tool when hbck will repair that?  Should we
> throw a warning and tell the user to run repair first?
> On Mar 16, 2013 9:17 AM, "Ted" <yuzhihong@gmail.com> wrote:
>
>> Chunhui replied to this question on review board.
>>
>> Basically the force option is to repair overlapping regions or table with
>> hole in its regions.
>>
>> Personally I think online merge should detect merging regions with hole in
>> between them and not require force flag in that case because logically
>> they're adjacent.
>>
>> Cheers
>>
>> On Mar 16, 2013, at 5:52 AM, Jean-Marc Spaggiari <jean-marc@spaggiari.org>
>> wrote:
>>
>> > Hi Ted,
>> >
>> > I jut gave it a look.
>> >
>> > I have updated it on the RB.
>> >
>> > Overall, this is very good and I'm eager to see that integrated! I'm
>> > waiting for this feature since the beginning ;)
>> >
>> > Regarding non adjacent regions merge? Will the system still be
>> > consistent after that? Or will hbck report some regions overlaps?
>> >
>> > JM
>> >
>> >
>> > 2013/3/16 Ted Yu <yuzhihong@gmail.com>:
>> >> Hi,
>> >> On behalf of Chunhui, I am requesting review for HBASE-7403 Online
>> Merge.
>> >>
>> >> This JIRA was created 3 months ago.
>> >> Chunhui has responded to review comments very promptly, including a
>> major
>> >> rewrite around the time split transaction was rewritten.
>> >>
>> >> This feature has widely been requested. I feel the patch is mostly
>> ready to
>> >> go in.
>> >> Here is brief recap of the steps.
>> >>
>> >> Process of merging two regions:
>> >>
>> >> a.client sends RPC (dispatch merging regions) to master
>> >> b.master moves the regions together (on the regionserver where the more
>> >> heavily loaded region resided)
>> >> c.master sends RPC (merge regions) to this regionserver
>> >> d.Regionserver executes the region merge transaction in the thread pool
>> >>
>> >> I think step b is a nice simplification for the problem. In previous
>> >> versions of the patch, the two merging regions stay on respective
>> servers
>> >> which required more complex coordination through zookeeper.
>> >>
>> >> High level comment as well as detailed review are both welcome.
>> >>
>> >> Thanks
>>