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From Héctor Izquierdo Seliva <izquie...@strands.com>
Subject Re: Thousands of tablesq
Date Fri, 30 Jul 2010 16:30:37 GMT

> 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.

I see. Usually a whole customer fits within a region. Actually, the 
number of customers that doesn't fit in a single region are only two or three.

But then another question comes up. Even if a put all the data in a single 
table, given that the keys are written in order, and given that several 
customers can fit in the same region, I'd had the exact same problem right?
I mean, if data from customer A to D sits in the same region within the same
table, the result is worse than having 4 different tables, as those can actually
sit in another region server right?

Is there a way to move a region manually to another machine?

> 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).

Even if all the htables are opened at the same time? 



El vie, 30-07-2010 a las 09:19 -0700, Jean-Daniel Cryans escribió:
> Inline.
> 
> J-D
> 
> 2010/7/30 Héctor 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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