Which is the equivalent function to Combiners of MapReduce in Spark?
I guess that it's combineByKey, but is combineByKey executed locally?
I understand than functions as reduceByKey or foldByKey aren't executed locally.
Reading the documentation looks like combineByKey is equivalent to
I think the simplest answer is that it's not really a separate concept
from the 'reduce' function, because Spark's API is a sort of simpler,
purer form of FP. It is just the same function that can be applied at
many points in an aggregation -- both map side (a la Combiners in
MapReduce) or reduce
