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https://issues.apache.org/jira/browse/HBASE-14867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15020207#comment-15020207
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Enis Soztutar commented on HBASE-14867:
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SimpleRN is too simple :)
I think we should introduce a more sophisticated RN.
- Run every 5 min by default rather than 30 min. This will be similar to
balancer.
- SRN computes only 1 action per run. This clearly will not work with with 10K
region tables. We should be able to compute a batch of normalization plans.
- RN should look at best possible actions in terms of splits or merges not
only for smallest or largest regions. In a single pass, we should be able to
calculate whether to split or merge for every pair of neighbors.
> SimpleRegionNormalizer needs to have better heuristics to trigger merge
> operation
> ---------------------------------------------------------------------------------
>
> Key: HBASE-14867
> URL: https://issues.apache.org/jira/browse/HBASE-14867
> Project: HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 1.2.0
> Reporter: Romil Choksi
>
> SimpleRegionNormalizer needs to have better heuristics to trigger merge
> operation. SimpleRegionNormalizer is not able to trigger a merge action if
> the table's smallest region has neighboring regions that are larger than
> table's average region size, whereas there are other smaller regions whose
> combined size is less than the average region size.
> For example,
> - Consider a table with six region, say r1 to r6.
> - Keep r1 as empty and create some data say, 100K rows of data for each of
> the regions r2, r3 and r4. Create smaller amount of data for regions r5 and
> r6, say about 27K rows of data.
> - Run the normalizer. Verify the number the regions for that table and also
> check the master log to see if any merge action was triggered as a result of
> normalization.
> In such scenario, it would be better to have a merge action triggered for
> those two smaller regions r5 and r6 even though either of them is not the
> smallest one
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