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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-4365) Add a decent heuristic for region size
Date Fri, 19 Oct 2012 19:03:12 GMT

     [ https://issues.apache.org/jira/browse/HBASE-4365?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

stack updated HBASE-4365:

    Release Note: 
Changes default splitting policy from ConstantSizeRegionSplitPolicy to IncreasingToUpperBoundRegionSplitPolicy.
 Splits quickly initially slowing as the number of regions climbs.

Split size is the number of regions that are on this server that all are of the same table,
squared, times the region flush size OR the maximum region split size, whichever is smaller.
 For example, if the flush size is 128M, then on first flush we will split which will make
two regions that will split when their size is 2 * 2 * 128M = 512M.  If one of these regions
splits, then there are three regions and now the split size is  3 * 3 * 128M =  1152M, and
so on until we reach the configured maximum filesize and then from there on out, we'll use

Be warned, this new default could bring on lots of splits if you have many tables on your
cluster.  Either go back to to the old split policy or up the lower bound configuration.

This patch changes the default split size from 64M to 128M.  It makes the region eventual
split size, hbase.hregion.max.filesize, 10G (It was 1G).
> Add a decent heuristic for region size
> --------------------------------------
>                 Key: HBASE-4365
>                 URL: https://issues.apache.org/jira/browse/HBASE-4365
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.92.1, 0.94.0
>            Reporter: Todd Lipcon
>            Assignee: stack
>            Priority: Critical
>              Labels: usability
>             Fix For: 0.94.0
>         Attachments: 4365.txt, 4365-v2.txt, 4365-v3.txt, 4365-v4.txt, 4365-v5.txt
> A few of us were brainstorming this morning about what the default region size should
be. There were a few general points made:
> - in some ways it's better to be too-large than too-small, since you can always split
a table further, but you can't merge regions currently
> - with HFile v2 and multithreaded compactions there are fewer reasons to avoid very-large
regions (10GB+)
> - for small tables you may want a small region size just so you can distribute load better
across a cluster
> - for big tables, multi-GB is probably best

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