What is MapReduce?

MapReduce is the heart of Hadoop, the programming framework used by thousands of Hadoop Clusters to treat massive amounts of data and big data. The MapReduce idea is comparable to the data processing methods of cluster scale-out. Two major Hadoop processes are referred to by the name MapReduce.

Firstly, map() work turns data into another collection of pieces breaking down into key/value pairs (tuples). Then reduction () is playing, wherein the map output, i.e. the tuples are used as the input and merged in smaller numbers. The map task is always done, prior to the reduction, as the name implies.