[jira] [Updated] (HBASE-24583) Normalizer can't actually merge empty regions when neighbor is larger than average size

["Nick Dimiduk (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-24583?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nick Dimiduk updated HBASE-24583:
---------------------------------
    Fix Version/s: 3.0.0-alpha-1

> Normalizer can't actually merge empty regions when neighbor is larger than average size
> ---------------------------------------------------------------------------------------
>
>                 Key: HBASE-24583
>                 URL: https://issues.apache.org/jira/browse/HBASE-24583
>             Project: HBase
>          Issue Type: Bug
>          Components: master, Normalizer
>    Affects Versions: 2.3.0
>            Reporter: Nick Dimiduk
>            Assignee: Nick Dimiduk
>            Priority: Major
>             Fix For: 3.0.0-alpha-1
>
>
> There are plenty of cases where empty regions can accumulate -- incorrect guessing at split points, old data is automatically expiring off, &c. The normalizer stubbornly refuses to handle this case, despite this being an original feature it was intended to support (HBASE-6613).
> Earlier discussion had concerns for a user pre-splitting a table and then the normalizer coming along and merging those splits away before they could be populated. Thus, right now, the default behavior via {{hbase.normalizer.merge.min_region_size.mb=1}} is to not split any region that's so small. Later, we added {{hbase.normalizer.merge.min_region_age.days=3}}, which prevents us from merging any region too young. So there's plenty of nobs for an operator to customize their behavior.
> But when I set {{hbase.normalizer.merge.min_region_size.mb=0}}, I still end up with stubborn regions that won't merge away. Looks like a large neighbor will prevent a merge from going through.



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