[HBASE-13103] [ergonomics] add region size balancing as a feature of master - ASF JIRA

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Details

Type: Improvement
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: None
Fix Version/s: 1.2.0, 1.3.0, 2.0.0
Component/s: Balancer, Usability
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Hadoop Flags:

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Release Note:

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This patch adds optional ability for HMaster to normalize regions in size (disabled by default, change hbase.normalizer.enabled property to true to turn it on). If enabled, HMaster periodically (every 30 minutes by default) monitors tables for which normalization is enabled in table configuration and performs splits/merges as seems appropriate. Users may implement their own normalization strategies by implementing RegionNormalizer interface and configuring it in hbase-site.xml.

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This patch adds optional ability for HMaster to normalize regions in size (disabled by default, change hbase.normalizer.enabled property to true to turn it on). If enabled, HMaster periodically (every 30 minutes by default) monitors tables for which normalization is enabled in table configuration and performs splits/merges as seems appropriate. Users may implement their own normalization strategies by implementing RegionNormalizer interface and configuring it in hbase-site.xml.

Description

Often enough, folks miss-judge split points or otherwise end up with a suboptimal number of regions. We should have an automated, reliable way to "reshape" or "balance" a table's region boundaries. This would be for tables that contain existing data. This might look like:

Admin#reshapeTable(TableName, int numSplits);

or from the shell:

> reshape TABLE, numSplits

Better still would be to have a maintenance process, similar to the existing Balancer that runs AssignmentManager on an interval, to run the above "reshape" operation on an interval. That way, the cluster will automatically self-correct toward a desirable state.