1.

What are the primary phases of reducer in Hadoop?

Answer»

In Hadoop, the PRIMARY phases of reducer are as follows:

  • Shuffle: In this phase, the mapper’s sorted OUTPUT becomes the input to the reducer.
  • Sort: In this phase, Hadoop sorts the input to Reducer using the same key. Both the Sort and Shuffle phases HAPPEN concurrently.
  • Reduce: This phase occurs after the sort and shuffle phase. In this phase, output values ASSOCIATED with a specific key are reduced to consolidate the data into the reducer FINAL output. Reducer output sorting is not there.


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