What Is The Main Difference Between Mapper And Reducer?

1.	What Is The Main Difference Between Mapper And Reducer?
Answer» Map method is called SEPARATELY for each key/value have been processed. It PROCESS input key/value PAIRS and emits intermediate key/value pairs. REDUCE method is called separately for each key/values list pair. It process intermediate key/value pairs and emits final key/value pairs. Both are initialize and called before any other method is called. Both don’t have any PARAMETERS and no output.

Answer»

Map method is called SEPARATELY for each key/value have been processed. It PROCESS input key/value PAIRS and emits intermediate key/value pairs.
REDUCE method is called separately for each key/values list pair. It process intermediate key/value pairs and emits final key/value pairs.
Both are initialize and called before any other method is called. Both don’t have any PARAMETERS and no output.

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