CODEWITHSUNDEEP
hadoopmapreducereducerscombiners
avhacker
avhacker

Reputation: 677

Mapreduce job: combiner without reducer

I noticed that if I set number of reducer to 0, the combiner won't work. Is it possible to use combiner without reducer? Thanks.

Upvotes: 2

Views: 889

Answers (2)

Aniket
Aniket

Reputation: 11

The whole purpose of the combiner is to 'combine' parts of mapper input so that the map outputs consume lesser network bandwidth when sent over to the reducer. Without the reducer, the whole point of using a combiner becomes moot. Hence, no, it is not possible.

Upvotes: 1

greedybuddha
greedybuddha

Reputation: 7507

No it's not. Even with a specified Reducer, combiners are not guaranteed to be used. So combiners are strictly optimizations that can be, but are not necessarily, called before Reducers. Without a reducer these will never be called.

Upvotes: 3

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