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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: Thousands of tablesq
Date Fri, 30 Jul 2010 16:19:48 GMT


2010/7/30 H├ęctor Izquierdo Seliva <izquierdo@strands.com>:
> Hi everyone.
> We are modeling our data based on one table per customer, so it's easy
> to drop one or add one without having to put offline while altering the
> table.
> I have to questions regarding this model:
> a) Our customers data size is very uneven. Some have millions of rows,
> some just a few thousands. This model of one table per customer will
> give good load balancing?

If your customers data fits in one region, then no. For example, if
you have 1k tables then you would have 1k regions, those will be
distributed to the region servers but if any of them becomes a
hotspot, too bad. BTW a region is the basic unit of load distribution
in HBase.

> b) Won't it be too heavy on resources to have thousands of htables
> opened?

Client side? I don't believe so, there's almost nothing kept in memory.

HBase side, 1k tables of 1 region is almost exactly like having 1
table of 1k regions. A single region server, on good hardware (i7s,
more than 8GB of RAM, couple of disks), handles a couple of hundreds
regions (although it depends a lot on your usage patterns).

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