A combiner reduces:
A) The number of values across different keys in the iterator supplied to a single reduce method call.
B) The amount of intermediate data that must be transferred between the mapper and reducer.
C) The number of input files a mapper must process.
D) The number of output files a reducer must produce.

Question

Quizplus · Accepted Answer

A combiner is used to reduce the amount of intermediate data by performing a local reduce task on the mapper's output before it is sent to the reducer, thus minimizing data transfer.

A Combiner Reduces