如何编写“仅地图"hadoop 作业? [英] How to write 'map only' hadoop jobs?

问题描述

我是 hadoop 的新手，我对 map-reduce 编程的风格很熟悉，但现在我遇到了一个问题:有时我只需要 map 的工作，我只需要直接将 map 结果作为输出，这意味着这里不需要减少阶段，我怎样才能做到这一点?

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?

推荐答案

这会关闭reducer.

This turns off the reducer.

job.setNumReduceTasks(0);

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

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