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HDFS Forum

Question on how MapReduce works?

  • #27802
    nietzsche
    Member

    I am trying to understand the order in which the following steps works. My understanding in general is that they happen in the following order (although Combiner can also happen during the reduce phase too.)

    Mapper
    Combiner
    Partitioner
    Shuffle/Sort
    Reducer

    Esp. confused about when Combiner, Partitioner and Shuffle/Sort happens.

    Any anyone confirm? I found this question among the Hortonworks sample test questions.

  • Author
    Replies
  • #27803
    tedr
    Moderator

    Hi Nietzsche,

    In my quick read over the docs that I can find, it looks like you have the order correct.

    Thanks,
    Ted.

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