You have written a Mapper which invokes the following five calls to the OutputColletor.collect method: output.collect (new Text ("Apple"), new Text ("Red") ) ; output.collect (new Text ("Banana"), new Text ("Yellow") ) ; output.collect (new Text ("Apple"), new Text ("Yellow") ) ; output.collect (new Text ("Cherry"), new Text ("Red") ) ; output.collect (new Text ("Apple"), new Text ("Green") ) ; How many times will the Reducer's reduce method be invoked?
A) 6
B) 3
C) 1
D) 0
E) 5

Question

Quizplus · Accepted Answer

The Reducer's reduce method is invoked once per unique key. Here, the unique keys are "Apple", "Banana", and "Cherry", so the reduce method will be invoked 3 times.

You Have Written a Mapper Which Invokes the Following Five