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From Angus He <angu...@gmail.com>
Subject Re: online automatic region merge
Date Fri, 09 Jul 2010 05:49:37 GMT
Considering the following case:
After  lowering the value of hbase.hregion.max.filesize and manually
starting a major compaction, I notice HBase start to split until all
regions meet the requirement.  But in the case of increasing the value
hbase.hregion.max.filesize , nothing happens.

Probably we could include onlinemerge utility in the following
release, or already in HBase 0.89 yet?
At lease we could do the merging operation manually.

By the way, onlinemerge utility seems to do the merging operation just
one pass,  probably it is better to merge recursively.

On Fri, Jul 9, 2010 at 12:27 PM, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
> HBASE-1621 isn't about automatic merging and it's still very experimental.
>
> The issue with doing automatically is that you have to figure that two
> regions, together, are smaller in size than the max size of a region
> to split. At the same time, it's not because two regions are small
> that you want to merge them, maybe they are taking inserts and are
> still growing. Lots of things to take into consideration, to solve a
> problem that is normally generated by a use case that's typically
> heavy on deletes or that updates the same cells a lot (creating too
> many versions that are often garbage collected... but after the splits
> happen). This is atypical, and can probably be solved by changing
> HBase is used. This is why this is low priority for the dev community
> and there's currently no planning done for it.
>
> That said, HBase is an open source project and we accept contributions 24/7 ;)
>
> J-D
>
> On Thu, Jul 8, 2010 at 8:51 PM, Angus He <angushe@gmail.com> wrote:
>> Hi guys,
>>
>> It seems that there is no support for automatic region merge in the
>> current implementation of HBase (0.20.5).
>> After searching in jira, I only found a command line utility called
>> onlinemerge in HBASE-1621.
>>
>> If so, any plan on automatic region merge?
>>
>> Thanks.
>>
>> --
>> Regards
>> Angus
>>
>



-- 
Regards
Angus

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