MCQ IN COMPUTER SCIENCE & ENGINEERING

Detailed explanation-1: -MapReduce is a programming model for processing and generating large data sets. Users specify a map function that processes a key/value pair to generate a set of intermediate key/value pairs, and a reduce function that merges all intermediate values associated with the same intermediate key.

Detailed explanation-2: -Mapper. Mapper maps input key-value pairs to a set of intermediate key-value pairs. Maps are the individual tasks that transform input records into intermediate records.

Detailed explanation-3: -The reduce function computes the final result for each group of key-value pairs with the same key. MapReduce model guarantees that key-value pairs with the same key are processed by the same reduce function. The set of all values returned by the reduce function is the final result of the MapReduce job.

Detailed explanation-4: -Mapper produces the intermediate key values pairs and these are read by reducer. Data corresponding to same key is grouped together and after some processing final output will be produced in the form of key value pairs.

Detailed explanation-5: -Intermediate Keys − They key-value pairs generated by the mapper are known as intermediate keys. Combiner − A combiner is a type of local Reducer that groups similar data from the map phase into identifiable sets.