MapReduce Forum

Files are already split in data node in blocks while copy file from local to hdf

  • #55418
    Hutashan Chandrakar
    Participant

    Files are already split in data node in blocks while copy file from local to hdfs then what is use of input splits in mapreduce framework

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  • #55421
    Steve Loughran
    Moderator

    Input splits let the mappers work on fractions of a larger file. As there’s usually three copies of each file in HDFS, you can run three mappers against different parts of the same block, giving you 3x the bandwidth, so hopefully 3x the performance

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