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From "Liu Shaohui (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-12451) IncreasingToUpperBoundRegionSplitPolicy may cause unnecessary region splits in rolling update of cluster
Date Thu, 21 May 2015 06:54:01 GMT

    [ https://issues.apache.org/jira/browse/HBASE-12451?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14553738#comment-14553738
] 

Liu Shaohui commented on HBASE-12451:
-------------------------------------

[~stack]
You mean this comment?

[~Apache9]
{quote}
I think the goal of IncreasingToUpperBoundRegionSplitPolicy is splitting fast when region
count is small(especially when smaller than region server count), and falling back to ConstantSizeSplitPolicy
when region count is larger than regionserver count(or twice, it depends) which means we already
have the ability to distribute request to every regionserver.

Add a minimum split size will break the first goal, right? And actually, there is a "hbase.increasing.policy.initial.size"
configuration in IncreasingToUpperBoundRegionSplitPolicy which specify the initial(minimum)
split size. And if you do not like the curve of split size, I think we should introduce a
new split policy instead?
{quote}
Agreed.
So I adjust the solution by using avg rather than RS count in the policy, and not setting
a minimum split size.



> IncreasingToUpperBoundRegionSplitPolicy may cause unnecessary region splits in rolling
update of cluster
> --------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-12451
>                 URL: https://issues.apache.org/jira/browse/HBASE-12451
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Liu Shaohui
>            Assignee: Liu Shaohui
>            Priority: Minor
>             Fix For: 2.0.0
>
>         Attachments: HBASE-12451-v1.diff, HBASE-12451-v2.diff
>
>
> Currently IncreasingToUpperBoundRegionSplitPolicy is the default region split policy.
In this policy, split size is the number of regions that are on this server that all are of
the same table, cubed, times 2x the region flush size.
> But when unloading regions of a regionserver in a cluster using region_mover.rb, the
number of regions that are on this server that all are of the same table will decrease, and
the split size will decrease too, which may cause the left region split in the regionsever.
Region Splits also happens when loading regions of a regionserver in a cluster. 
> A improvment may set a minimum split size in IncreasingToUpperBoundRegionSplitPolicy
> Suggestions are welcomed. Thanks~



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