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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (HBASE-420) Adjacent small regions should be automatically merged
Date Sun, 08 Jun 2014 21:53:02 GMT

     [ https://issues.apache.org/jira/browse/HBASE-420?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Andrew Purtell resolved HBASE-420.

    Resolution: Not a Problem

Other issues cover this in various ways. Let's retire this golden oldie.

> Adjacent small regions should be automatically merged
> -----------------------------------------------------
>                 Key: HBASE-420
>                 URL: https://issues.apache.org/jira/browse/HBASE-420
>             Project: HBase
>          Issue Type: Improvement
>          Components: master, regionserver
>            Reporter: Bryan Duxbury
>            Priority: Minor
> Region merge functionality exists in HBase today, but merges are triggered manually (in
theory only, because there is no admin tool for doing so). Instead of relying on an admin
to note and merge regions, the Master should detect adjacent undersized regions and automatically
merge them.
> Other than the case when a table has exactly one region, region sizes should always be
between 1/2x and 1x the split size. For instance, if the max file size is 256MB, steady-state,
regions will be between 128 and 256MB. If we find two regions near each other that are less
than some threshold when summed together, they are candidates for merging. For instance, we
could set the threshold to 1/2x max file size, so if one region was 50MB and the other was
16MB, they would be mergeable. 
> The only time that regions small enough to merge should exist is when there have been
significant deletions. Otherwise, regions will always stay in the 1/2 to 1x range. 

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