Mapreduce algorithm

Question

Describe the general mapreduce algorithm.

Answer 1

The mapreduce algorithm mainly has four main phases:

a) Map,

b) Combine,

c) Shuttle and sort

d) Phase output

Mappers simply execute on unsorted key/values pairs. They form the intermediate keys. Once these keys are ready the combiners pair the key/value pairs along with the right key. The shuttle/sort is done by the framework their role being to group the data and transfer it. Once completed, it will proceed for output through the phase output process.