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From David Medinets <>
Subject Re: Determining tablets assigned to table splits, and the number of rows in each tablet
Date Sat, 04 Oct 2014 16:04:35 GMT
I did some work to explain these topics at
If you have the luxury of writing the ingest code you can use
Cardinality Estimates using techniques described in

On Sat, Oct 4, 2014 at 12:23 AM, Dylan Hutchison <> wrote:
> This is for Accumulo 1.6.  Suppose we have the table splits
> c
> g
> w
> Does anyone know how to determine
> the number of tablets assigned to each table split range?
> For this example, this is the number of tablets in the ranges (-Inf,c),
> (c,g), (g,w), (w,Inf).  Or is the design 1-1, that is, for each table split
> range there is exactly one tablet?
> the number of rows inside all the tablets occupying a table split range?
> For this example, this is the total number of rows among all tablets in the
> ranges (-Inf,c), (c,g), (g,w), (w,Inf).
> We use this count to verify how well manually set table splits are load
> balancing in the tables.
> Some context: I wrote functions that found these numbers two years ago
> working on D4M in Accumulo 1.5.  I took the dark route of using non-public
> Accumulo API to get TabletServer information, get TabletStats information,
> and find the matchings to a table's splits by scanning the extents listed in
> the METATABLE.  I can share the code if anyone is curious.  It's not pretty,
> but it did the job.
> Moving forward as we aim to upgrade to Accumulo 1.6, we should determine the
> tablet split information the right way, not by reverse engineering Accumulo.
> Any suggestions?
> Thanks,
> Dylan Hutchison
> --

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