Which function in spark is used to combine two RDDs by keys

Question

Let us say I have the following two RDDs, with the following key-pair values.

rdd1 = [ (key1, [value1, value2]), (key2         


        

Answer 1

I would union the two RDDs and to a reduceByKey to merge the values.

(rdd1 union rdd2).reduceByKey(_ ++ _)