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From "Alex Liu (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-5544) Hadoop jobs assigns only one mapper in task
Date Mon, 27 May 2013 21:44:20 GMT


Alex Liu commented on CASSANDRA-5544:

[~shamim] How many splits do you get for each hadoop node? You can set ConfigHelper.setInputSplitSize
to a smaller number to get more mappers for your pig job. The existing CassandraStorage class
doesn't set it, so it uses the defualt value of 64k. So if your nodes has less than 64k rows,
it will have only one mapper.
> Hadoop jobs assigns only one mapper in task 
> --------------------------------------------
>                 Key: CASSANDRA-5544
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Hadoop
>    Affects Versions: 1.2.1
>         Environment: Red hat linux 5.4, Hadoop 1.0.3, pig 0.11.1
>            Reporter: Shamim Ahmed
>            Assignee: Alex Liu
>         Attachments: Screen Shot 2013-05-26 at 4.49.48 PM.png
> We have got very strange beheviour of hadoop cluster after upgrading 
> Cassandra from 1.1.5 to Cassandra 1.2.1. We have 5 nodes cluster of Cassandra, where
three of them are hodoop slaves. Now when we are submitting job through Pig script, only one
map assigns in task running on one of the hadoop slaves regardless of 
> volume of data (already tried with more than million rows).
> Configure of pig as follows:
> export PIG_HOME=/oracle/pig-0.10.0
> export PIG_CONF_DIR=${HADOOP_HOME}/conf
> export PIG_RPC_PORT=9160
> export PIG_PARTITIONER=org.apache.cassandra.dht.Murmur3Partitioner
> Also we have these following properties in hadoop:
>  <property>
>  <name></name>
>  <value>10</value>
>  </property>
>  <property>
>  <name></name>
>  <value>4</value>
>  </property>

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