When a reduce class also serve as a combiner?

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When can a reduce class also serve as a combiner without affecting the output of a MapReduce program?
Aug 8, 2018 in Big Data Hadoop by Shubham
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1 answer to this question.

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It will act as a combiner when the types of the reduce operation’s input key and input value match the types of the reducer’s output key and output value and when the reduce operation is both communicative and associative.
answered Aug 8, 2018 by nitinrawat895
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