So, if that's the case, and you argument makes sense understanding how scan versus get works, I'd have to write a custom InputFormat class that looks like the TableInputFormat class, but uses a get(or series of gets) rather than a scan object as the current table mapper does?
James Kilbride -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jean-Daniel Cryans Sent: Tuesday, July 06, 2010 12:53 PM To: [email protected] Subject: Re: MapReduce HBASE examples > > > Does this make any sense? > > Not in a MapReduce context, what you want to do is a LIKE with a bunch of values right? Since a mapper will always read all the input that it's given (minus some filters like you can do with HBase), whatever you do will always end up being a full table scan. You "could" solve your problem by configuring your Scan object with a RowFilter that knows about the names you are looking for, but that still ends up being a full scan on the region server side so it will be slow and will generate a lot of IO. WRT examples, HBase ships with a couple of utility classes that can also be used as examples. The Export class has the Scan configuration stuff: http://github.com/apache/hbase/blob/0.20/src/java/org/apache/hadoop/hbase/mapreduce/Export.java J-D
