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https://issues.apache.org/jira/browse/HBASE-3373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12988214#action_12988214
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Matt Corgan commented on HBASE-3373:
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Have you guys considered using a consistent hashing method to choose which
server a region belongs to? You would create ~50 buckets for each server by
hashing serverName_port_bucketNum, and then hash the start key of each region
into the buckets.
There are a few benefits:
* when you add a server it takes an equal load from all existing servers
* if you remove a server it distributes its regions equally to the remaining
servers
* adding a server does not cause all regions to shuffle like round robin
assignment would
* assignment is nearly random, but repeatable, so no hot spots
* when a region splits the front half will stay on the same server, but the
back half will usually be sent to another server
And a few drawbacks:
* each server wouldn't end up with exactly the same number of regions, but they
would be close
* if a hot spot does end up developing, you can't do anything about it, at
least not unless it supported a list of manual overrides
> Allow regions of specific table to be load-balanced
> ---------------------------------------------------
>
> Key: HBASE-3373
> URL: https://issues.apache.org/jira/browse/HBASE-3373
> Project: HBase
> Issue Type: Improvement
> Components: master
> Affects Versions: 0.20.6
> Reporter: Ted Yu
> Fix For: 0.92.0
>
>
> From our experience, cluster can be well balanced and yet, one table's
> regions may be badly concentrated on few region servers.
> For example, one table has 839 regions (380 regions at time of table
> creation) out of which 202 are on one server.
> It would be desirable for load balancer to distribute regions for specified
> tables evenly across the cluster. Each of such tables has number of regions
> many times the cluster size.
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