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

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0, 1.3.0, 2.0.0
• Component/s: Balancer, Usability
• Hadoop Flags: Reviewed

Release Note

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.

• Assignee: Mikhail Antonov
• Reporter: Nick Dimiduk
• Created: 25/Feb/15 19:19
• Updated: 16/Jun/22 01:16
• Resolved: 23/Jun/15 06:08

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.

Issue Links

• is related to: HBASE-14838 Clarify that SimpleRegionNormalizer does not merge empty (<1MB) regions
• is related to: HBASE-13964 Skip region normalization for tables under namespace quota
• is related to: HBASE-15073 Finer grained control over normalization actions for RegionNormalizer
• relates to: HBASE-15098 Normalizer switch in configuration is not used
• relates to: HBASE-14367 Add normalization support to shell
• relates to: HBASE-15124 Document the new 'normalization' feature in refguid
• supercedes: HBASE-7629 Master initiated automatic region merges
• supercedes: HBASE-3521 region be merged with others automatically when all data in the region has expired and removed, or region gets too small.
• links to: review board