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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15249) Provide lower bound on number of regions in region normalizer for pre-split tables
Date Wed, 17 Feb 2016 03:51:18 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15149801#comment-15149801
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Anoop Sam John commented on HBASE-15249:
----------------------------------------

Thanks for the explanation of ur usage [~swagle].  Yes what I was saying is even if write
reqs to a region is very small in numbers, still it may not be correct to merge it with another.
 As there is clear indication that this region is growing. May be after some time it might
be getting much more write load.   When 2 regions are done with all its writes and the data
will be used only for read purpose, it may get merged.. The challenge is how we know whether
region is done with its writes :-)

> Provide lower bound on number of regions in region normalizer for pre-split tables
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-15249
>                 URL: https://issues.apache.org/jira/browse/HBASE-15249
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Assignee: Ted Yu
>         Attachments: HBASE-15249.v1.txt, HBASE-15249.v2.txt
>
>
> AMS (Ambari Metrics System) developer found the following scenario:
> Metrics table was pre-split with many regions on large cluster (1600 nodes).
> After some time, AMS stopped working because region normalizer merged the regions into
few big regions which were not able to serve high read / write load.
> This is a big problem since the write requests flood the regions faster than the splits
can happen resulting in poor performance.
> We should consider setting reasonable lower bound on region count.
> If the table is pre-split, we can use initial region count as the lower bound.



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