What happens in a MapReduce job when you set the number of reducers to one

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I am new to Hadoop and I know that default replication factor of Hadoop is 3 but my question is that what happens to a MapReduce job when we set the number of reducers to one?
Jul 31, 2018 in Big Data Hadoop by Shubham
 • 13,490 points • 1,835 views

1 answer to this question.

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If you set number of reducers as 1 so what happens is that a single reducer gathers and processes all the output from all the mappers. The output is written to a single file in HDFS.

Hope you got the answer.
answered Jul 31, 2018 by nitinrawat895
 • 11,380 points

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