In MapReduce - Zero Reduce Task.



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In MapReduce Program, is it possible to have zero Reduce Task. will such scenario comes.  If so can i get some example for the scenario.

Thanks

Shankar


2 Answer(s)


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Yes we can do it by using 

job.setNumReduceTasks(0);

Basically wherever we have to not do any aggregation we can skip the Reduce Task


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Yes, Map Only Map Reduce jobs are common. In these jobs, you configure number of reduce tasks to zero.

 

job.setnumofreducetasks(0)

 

Examples:

1. Masking of sensitive columns in a data set.

2. Map side join 

3. Filtering