Unfortunately I've just tried with a new cluster with RandomPartitioner and it doesn't work better :

it may come from hadoop/pig modifications :

18:02:53|elia:hadoop cyril$ git diff --stat cassandra-1.1.5..cassandra-1.2.1 .
 .../apache/cassandra/hadoop/BulkOutputFormat.java  |   27 +--
 .../apache/cassandra/hadoop/BulkRecordWriter.java  |   55 +++---
 .../cassandra/hadoop/ColumnFamilyInputFormat.java  |  102 ++++++----
 .../cassandra/hadoop/ColumnFamilyOutputFormat.java |   31 ++--
 .../cassandra/hadoop/ColumnFamilyRecordReader.java |   76 ++++----
 .../cassandra/hadoop/ColumnFamilyRecordWriter.java |   24 +--
 .../apache/cassandra/hadoop/ColumnFamilySplit.java |   32 ++--
 .../org/apache/cassandra/hadoop/ConfigHelper.java  |   73 ++++++--
 .../cassandra/hadoop/pig/CassandraStorage.java     |  214 +++++++++++++-------
 9 files changed, 380 insertions(+), 254 deletions(-)

Can anyone help on getting more mapper running ? Maybe we should open a bug report ?
-- 
Cyril SCETBON

On May 5, 2013, at 8:45 AM, Shamim <srecon@yandex.ru> wrote:

Hello,
  We have also came across this issue in our dev environment, when we upgrade Cassandra from 1.1.5 to 1.2.1 version. I have mentioned this issue in few times in this forum but haven't got any answer yet. For quick work around you can use pig.splitCombination false in your pig script to avoid this issue, but it will make one of your task with a very big amount of data. I can't figure out why this happening in newer version of Cassandra, strongly guess some thing goes wrong in Cassandra implementation of LoadFunc or in Murmur3Partition (it's my guess).
Here is my earliar post
http://www.mail-archive.com/user@cassandra.apache.org/msg28016.html
http://www.mail-archive.com/user@cassandra.apache.org/msg29425.html

Any comment from authors will be highly appreciated
P.S. please keep me in touch with any solution or hints.

--
Best regards
  Shamim A.



03.05.2013, 19:25, "cscetbon.ext@orange.com" <cscetbon.ext@orange.com>:
Hi,
I'm using Pig to calculate the sum of a columns from a columnfamily (scan of all rows) and I've read that input data locality is supported at http://wiki.apache.org/cassandra/HadoopSupport
However when I execute my Pig script Hadoop assigns only one mapper to the task and not one mapper on each node (replication factor = 1).  FYI, I've 8 mappers available (2 per node).
Is there anything that can disable the data locality feature ?

Thanks
--
Cyril SCETBON

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