Question

Point out the wrong statement.

(a) The Mapper outputs are sorted and then partitioned per Reducer

(b) The total number of partitions is the same as the number of reduce tasks for the job

(c) The intermediate, sorted outputs are always stored in a simple (key-len, key, value-len, value) format

(d) None of the mentioned

The question was asked in an international level competition.

My doubt is from Mapreduce Development in chapter Developing a MapReduce Application of Hadoop

Answer 1

Right choice is (d) None of the mentioned

Easiest explanation: All intermediate values associated with a given output key are subsequently grouped by the framework, and passed to the Reducer(s) to determine the final output.