Briefing Cloudera Knowledge

How many times will the Reducer’s reduce method be invoked.

You have written a Mapper which invokes the following five calls to the outputcollector.collect
method:
C:\Documents and Settings\RraAsShHiIdD\Desktop\untitled.JPG
How many times will the Reducer’s reduce method be invoked.

A.
0

B.
1

C.
3

D.
5

E.
6

Explanation:
Note:
org.apache.hadoop.mapred Interface OutputCollector<K,V>
Collects the <key, value> pairs output by Mappers and Reducers.
OutputCollector is the generalization of the facility provided by the Map-Reduce framework to
collect data output by either the Mapper or the Reducer i.e. intermediate outputs or the output of
the job.