When can a reduce class also serve as a combiner without affecting the output of a MapReduce program?

Question

Options

• AWhen the types of the reduce operation's input key and input value match the types of the reducer's output
• BWhen the signature of the reduce method matches the signature of the combine method.
• CAlways. Code can be reused in Java since it is a polymorphic object-oriented programming language.
• DAlways. The point of a combiner is to serve as a mini-reducer directly after the map phase to increase
• ENever. Combiners and reducers must be implemented separately because they serve different purposes.

• A
  77% (41)
• B
  4% (2)
• C
  6% (3)
• D
  11% (6)
• E
  2% (1)

Explanation

You can use your reducer code as a combiner if the operation performed is commutative and

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