Map Reduce

Map Reduce is another major component of the Hadoop Framework. This functions as the compute part (while the other center component is Storage as explained earlier). Map reduce offers a general purpose framework for the distribution of your work through various nodes and then the combination of the results for the purpose of getting the end results you desire. Map Reduce is also referred to as a programming model. The procedure of the map() helps in dividing your tasks over various queues, in a manner that each task can be autonomously executed. The procedure of the reduce() execute data summary from the individual nodes’ output, for the purpose of obtaining the end result of your task. Just as expected, a specific task may incorporate various stages of map reduce.

https://hadoop.apache.org/docs/r1.2.1/mapred_tutorial.html

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