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From "Jim Kellerman (POWERSET)" <Jim.Keller...@microsoft.com>
Subject RE: for one specific row: are the values of all columns of one family stored in one physical/grid node?
Date Thu, 11 Jun 2009 08:10:15 GMT
To expand on Erik's explanation:

A table is made up of one or more regions.

Each region contains all the data for all the rows between its start and end keys.

Each region owns multiple stores, one per column family.

Each region is served from one region server (but regions can migrate from one
region server to another due to region server death, load balancing, etc.)

Based on the row key, the client can determine which region server to talk to. The
client can then fetch from any of the column families for that row by talking to
that one region server.

If you haven't read the Bigtable paper (http://labs.google.com/papers/bigtable.html )
it is highly recommended that you do, because the goal from the start of the HBase
project has to produce something that is as close to Bigtable as possible (esp from
the client point of view), in an open source project so that there is no vendor lock-in.

---
Jim Kellerman, Powerset (Live Search, Microsoft Corporation)


> -----Original Message-----
> From: Erik Holstad [mailto:erikholstad@gmail.com]
> Sent: Thursday, June 11, 2009 12:51 AM
> To: hbase-user@hadoop.apache.org
> Subject: Re: for one specific row: are the values of all columns of
> one family stored in one physical/grid node?
>
> Hi!
> Just to be clear what is being said here is that every region
> contains a set
> of stores which holds
> one family each, for that specific row range. And one store can hold
> many
> files with data for that
> store, which in the case of a major compaction turns into one single
> file.
>
> Erik

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