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From Harsh J <ha...@cloudera.com>
Subject Re: an emtry region
Date Sun, 12 Aug 2012 14:36:19 GMT
You're right there - compactions does not merge region boundaries.
They just merge the accumulated (flushed, etc.) storefiles belonging
to each region, for every region thats fragmented over time.

On Fri, Aug 10, 2012 at 2:47 PM, J Mohamed Zahoor <jmozah@gmail.com> wrote:
> No. I just now learnt that compactions does not merge regions... (need to
> verify this in code though).
>
> ./Zahoor
>
> On Fri, Aug 10, 2012 at 2:43 PM, J Mohamed Zahoor <jmozah@gmail.com> wrote:
>
>> Hi
>>
>> I think major compaction does this for you.
>> But any way there is a utility called Merge which will merge adjoining
>> Regions.
>>
>> more here http://hbase.apache.org/book/ops.regionmgt.html
>>
>> ./zahoor
>>
>>
>> On Fri, Aug 10, 2012 at 1:47 PM, samar kumar <samar.opensource@gmail.com>wrote:
>>
>>> @Zahoor thanks
>>> Looks good.. Is there a way to merge regions automatically??
>>> Assuming there was a split and then lot of deletes on each region. Making
>>> each region quite light weight can we merge those two regions to one
>>> (automatically, like some kind of config)
>>>
>>> On 10/08/12 1:07 PM, "J Mohamed Zahoor" <jmozah@gmail.com> wrote:
>>>
>>> >Look at this post for more about Catalog Janitor
>>> >
>>> >http://blog.zahoor.in/2012/08/hbase-hmaster-architecture/
>>> >
>>> >On Fri, Aug 10, 2012 at 12:45 PM, J Mohamed Zahoor <jmozah@gmail.com>
>>> >wrote:
>>> >
>>> >> Hi
>>> >> Region don't remain for ever.
>>> >> Catalog Janitor chore will scan for unused regions in the META and
>>> >>garbage
>>> >> collect. by default it is triggered every 300 sec. The property
>>> >> "hbase.catalogjanitor.interval" is used for this.
>>> >>
>>> >> ./Zahoor
>>> >>
>>> >>
>>> >> On Tue, Aug 7, 2012 at 4:44 PM, Anoop Sam John <anoopsj@huawei.com>
>>> >>wrote:
>>> >>
>>> >>> Hi,
>>> >>> >Now could I merge those two regions or automatically delete
that
>>> >>>region.
>>> >>> There is no automatic deletion of regions which will happen within
>>> >>>HBase.
>>> >>> Yes u can write code which can do the merge of the 2 regions so
that
>>> >>>only
>>> >>> one region will exists.
>>> >>> Having more and more empty regions(unwanted region) is an overhead
>>> >>>only.
>>> >>>
>>> >>> -Anoop-
>>> >>> ________________________________________
>>> >>> From: samar kumar [samar.opensource@gmail.com]
>>> >>> Sent: Tuesday, August 07, 2012 4:32 PM
>>> >>> To: user@hbase.apache.org
>>> >>> Subject: Re: an emtry region
>>> >>>
>>> >>> @Syed Thanks for respond
>>> >>>  Lets assume that we had a huge table which got split into two
>>> regions.
>>> >>> Later all the rows for that region was deleted. So now we have one
>>> >>>table,
>>> >>> two regions with the second region empty. Table could possible have
>>> >>>more
>>> >>> that one CF. also can't remove the CF because it is still relevant
and
>>> >>> data is present in the first region for that particular CF.
>>> >>> Now could I merge those two regions or automatically delete that
>>> >>>region.
>>> >>> Samar
>>> >>>
>>> >>> On 07/08/12 4:19 PM, "syed kather" <in.abdul@gmail.com> wrote:
>>> >>>
>>> >>> > samar kumar,
>>> >>> >
>>> >>> >   If all the rows of an region are deleted what happens to
the
>>> >>>region.
>>> >>> >Would it still exist .?
>>> >>> > Yes it will exist . Whenever you create a family HBase will
create
>>> >>> >a separate Space for that Column Family . If there data available
for
>>> >>> then
>>> >>> >that data will be written to HFile which is create for that
column
>>> >>>family
>>> >>> >space. If you need  to remove column family completely you have
a
>>> >>>write
>>> >>> >the separate code to handle this
>>> >>> >
>>> >>> >Also what is the cost of having a empty region?
>>> >>> >I also don't have proper explanation for this
>>> >>> >
>>> >>> >
>>> >>> >On Tue, Aug 7, 2012 at 4:03 PM, samar kumar
>>> >>> ><samar.opensource@gmail.com>wrote:
>>> >>> >
>>> >>> >> Please read the subject as  "an empty region"
>>> >>> >>
>>> >>> >> From:  samar kumar <samar.opensource@gmail.com>
>>> >>> >> Date:  Tue, 07 Aug 2012 15:57:04 +0530
>>> >>> >> To:  "user@hbase.apache.org" <user@hbase.apache.org>
>>> >>> >> Subject:  an emtry region
>>> >>> >>
>>> >>> >> Hi Hbase users,
>>> >>> >> If all the rows of an region are deleted what happens to
the
>>> region.
>>> >>> >>Would
>>> >>> >> it still exist . It can be removed by writing some code
but can it
>>> >>>be
>>> >>> >> removed automatically. Also what is the cost of having
a empty
>>> >>>region.
>>> >>> >> Regards,
>>> >>> >> Samar
>>> >>> >>
>>> >>> >>
>>> >>> >>
>>> >>>
>>> >>
>>> >>
>>>
>>>
>>>
>>



-- 
Harsh J

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