mapreduce - How to write 'map only' hadoop jobs?

Question

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 result directly as output, which means reduce phase is not needed here, how can I achive that?

question from:https://stackoverflow.com/questions/9394409/how-to-write-map-only-hadoop-jobs

Answer 1

This turns off the reducer.

job.setNumReduceTasks(0);

http://hadoop.apache.org/docs/current/api/org/apache/hadoop/mapreduce/Job.html#setNumReduceTasks(int)