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From Billie J Rinaldi <billie.j.rina...@ugov.gov>
Subject Re: tablet distribution
Date Fri, 13 Jul 2012 21:21:49 GMT
On Friday, July 13, 2012 5:14:53 PM, "John Vines" <john.w.vines@ugov.gov> wrote:
> Sounds like you want to use the TableLoadBalancer which will try to
> even balance all tablets on a table-by-table basis.

To use this, set "master.tablet.balancer" to "org.apache.accumulo.server.master.balancer.TableLoadBalancer".
 This has been made the default balancer as of 1.4.1.

Billie


> John
> 
> 
> On Fri, Jul 13, 2012 at 5:09 PM, ameet kini < ameetkini@gmail.com >
> wrote:
> 
> 
> Thanks, I was looking for something of the equivalent:
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HBaseAdmin.html#move(byte[],
> byte[])
> 
> 
> The use case is common enough that there may be some other way to do
> what I want. I have a table that doesn't have its tablets distributed
> evenly. At the system (instance?) level, they are evenly distributed,
> but not at this particular table level.
> 
> 
> The docs seem to suggest that pre-splitting a table would
> automatically guarantee that the tablets would be distributed evenly
> across the nodes of the cluster. I see that pre-splitting guarantees
> that you have that many tablets, but not necessarily that they are
> evenly distributed. Maybe if the instance had only one table, then it
> would be forced to distribute its tablets.
> 
> 
> 
> Thanks,
> Ameet
> 
> 
> PRE-SPLITTING TABLES
> 
> 
> Accumulo will balance and distribute tables accross servers. Before a
> table gets large, it will be maintained as a single tablet on a single
> server. This limits the speed at which data can be added or queried to
> the speed of a single node. To improve performance when the a table is
> new, or small, you can add split points and generate new tablets.
> 
> In the shell:
> root @myinstance > createtable newTable root @myinstance > addsplits -
> t newTable g n t
> 
> This will create a new table with 4 tablets. The table will be split
> on the letters g'', n'', and ``t'' which will work nicely if the row
> data start with lower-case alphabetic characters. If your row data
> includes binary information or numeric information, or if the
> distribution of the row information is not flat, then you would pick
> different split points. Now ingest and query can proceed on 4 nodes
> which can improve performance.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> On Fri, Jul 13, 2012 at 3:04 PM, Eric Newton < eric.newton@gmail.com >
> wrote:
> 
> 
> Yes, you need to write your own tablet balancer.
> 
> -Eric
> 
> 
> 
> On Fri, Jul 13, 2012 at 2:48 PM, ameet kini < ameetkini@gmail.com >
> wrote:
> >
> > Hi,
> >
> > Is there a way to force a tablet to move to a particular tablet
> > server?
> >
> > Thanks,
> > Ameet

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