Explain Apache Hadoop's MapReduce .

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Apache Hadoop's MapReduce 

  • Apache Hadoop's MapReduce is the most widely used batch data processing. The diagram below explains in detail how Hadoop processes data using MapReduce.


  • MapReduce Hadoop MapReduce is a Java-based system for processing large datasets. It reads data from the HDFS and divides the dataset into smaller pieces. Each piece is then scheduled and distributed for processing among the nodes available in the Hadoop cluster. Each node performs the required computation on the chunk of data and is intermediate results obtained are written back to the HDFS. These intermediate outputs may then be sembled, split, and redistributed for further processing until final results are written back to HDFS.
  • As already discussed above, the MapReduce data processing programming model consists of two different jobs executed by programs: a Map job and a Reduce job. Typically, the Map operation begins by turning a collection of data into another set of data in which individual pieces of the data are broken down into tuples consisting of key-value pairs. One or more Map tasks can then shuffle, sort, and process these key-value pairs. The Reduce task typically takes as input the results of a Map task and merges those data tuples into a smaller collection of tuples.
  • Batch processing, in a nutshell, is a way of waiting and performing everything periodically such as at the end of the day, week, or month. In the enterprise, during the specified period, the cumulative data will be large. So, to handle such big data, distributed computing environment, and the MapReduce technique can play a vital role.

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