I\'m a novice on hadoop, I\'m getting familiar to the style of map-reduce programing but now I faced a problem : Sometimes I need only map for a job and I only need the map
This turns off the reducer.
job.setNumReduceTasks(0);
http://hadoop.apache.org/docs/current/api/org/apache/hadoop/mapreduce/Job.html#setNumReduceTasks(int)