Home > Software > BIGDATA > HADOOP
Interview Questions   Tutorials   Discussions   Programs   Videos   Discussion   

HADOOP - What is next step after Mapper or MapTask?

asked SRVMTrainings August 9, 2013 07:24 AM  

What is next step after Mapper or MapTask?


2 Answers

answered By   0  
After Map task , Reducer task starts. 

Reducer has 3 primary phases:
Shuffle, sort & Reduce.

Reducer combines the multiple outputs of Mapper (Map Task) to one standard output.
   add comment

answered By   0  
After Map Task, sorting and shuffling phase coming to the picture, In this phase sorted and merge the data, once complete the sort and shuffling phase reducer will coming to the picture. 
mapper output: (hi,1) (hi,1) (hi,1) (hi,1) (what,2) (what,3) (what,3)
Sort and Shuffle: (hi, {1,1,1,1,}),(what,{2,3,3,}).................)
Reducer Input: (hi, {1,1,1,1,}),(what,{2,3,3,}).................)
   add comment

Your answer

Join with account you already have



Ready to start your tutorial with us? That's great! Send us an email and we will get back to you as soon as possible!