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From Markus Mock <markus.m...@gmail.com>
Subject Multiple input column families in Cassandra Hadoop mapreduce
Date Fri, 15 Jul 2011 08:34:36 GMT
Hello,

with org.apache.cassandra.hadoop.ConfigHelper.setInputColumnFamily I can set
up the map phase to read from one column family. Is it possible to have
multiple mapper classes each mapping over their own column family so that
data from multiple column families can be "joined" in the reduce phase? I
didn't find any documentation on how to do that.

One workaround I see is to do several MRs write the data from the different
column families in a single helper column family and then do the desired
computation but I am trying to avoid that if possible. Any suggestions on
how to do this without running multiple MRs and instead read from multiple
column families in one go?

Thanks.

  -- Markus

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