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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: hbase mapreduce scan
Date Mon, 05 Apr 2010 16:57:02 GMT
You want to put the result in a HashMap? MapReduce is a batch
processing framework that runs multiple parallel JVMs over a cluster
of machines so I don't see how you could simply output in a HashMap
(unless you don't mind outputting on disk, then reading it back into a
HashMap).

So I will guess that you want to do a live query against HBase, here
MR won't help you since that is meant for bulk processing which
usually takes more than a minute.

What you want to use is a Scan, using HTable. The unit tests have tons
of example on how to use a scanner, look in the
org.apache.hadoop.hbase.client package, so will find what you need.
The main client package also contains some examples
http://hadoop.apache.org/hbase/docs/r0.20.3/api/org/apache/hadoop/hbase/client/package-summary.html

J-D

On Sun, Apr 4, 2010 at 11:18 AM, Jürgen Jakobitsch <jakobitschj@punkt.at> wrote:
> hi,
>
> i'm totally new to hbase and mapreduce and could really need some
> pointer into the right direction for the following situation.
>
> i managed to run a basic mapreduce example - analog to Export.java
> in the hbase.mapreduce package.
>
> what i need to achieve is the following :
>
> do a map/reduce scan on a hbase table and put the results
> into a HashMap.
>
> could someone point me to an example.
>
> any help really appreciated
>
> wkr turnguard.com/turnguard
>
> --
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