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https://issues.apache.org/jira/browse/HBASE-14838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15013175#comment-15013175
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Mikhail Antonov commented on HBASE-14838:
-----------------------------------------
Interesting, to be honest I did think about this scenario :)
I think original incentive was to provide a tool to 1) automatically fix skews
in data distribution in regions (result of suboptimal choice of pre-chosen
split points or something) 2) merge up small regions (either the ones which
shrunk after major compaction, or old small regions after migration to new
version with bigger "standard" region size)
If you have 5-6 empty regions and no data in there, do you want normalizer to
merge them together? I would assume (if I see this scenario) that someone has
just pre-split the table, and it should be left as is, until some data comes in
and skews in distribution start to show up, at which point normalizer would
kick in? Am I missing something?
> SimpleRegionNormalizer does not merge empty region of a table
> -------------------------------------------------------------
>
> Key: HBASE-14838
> URL: https://issues.apache.org/jira/browse/HBASE-14838
> Project: HBase
> Issue Type: Bug
> Affects Versions: 1.2.0, 1.1.2
> Reporter: Romil Choksi
>
> SImpleRegionNormalizer does not merge empty region of a table
> Steps to repro:
> - Create an empty table with few, say 5-6 regions without any data in any of
> them
> - Verify hbase:meta table to verify the regions for the table or check
> HMaster UI
> - Enable normalizer switch and normalization for this table
> - Run normalizer, by 'normalize' command from hbase shell
> - Verify the regions for table by scanning hbase:meta table or checking
> HMaster web UI
> The empty regions are not merged on running the region normalizer. This seems
> to be an edge case with completely empty regions since the Normalizer checks
> for: smallestRegion (in this case 0 size) + smallestNeighborOfSmallestRegion
> (in this case 0 size) > avg region size (in this case 0 size)
> thanks to [~elserj] for verifying this from the source code side
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