hadoop: difference between 0 reducer and identity reducer?

Question

I am just trying to confirm my understanding of difference between 0 reducer and identity reducer.

• 0 reducer means reduce step will be skipped and mapper outp

Answer 1

It depends on your business requirements. If you are doing a wordcount you should reduce your map output to get a total result. If you just want to change the words to upper case, you don't need a reduce.