public class ShuffleDependency<K,V,C>
:: DeveloperApi ::
Represents a dependency on the output of a shuffle stage. Note that in the case of shuffle,
the RDD is transient since we don't need it on the executor side.
param: _rdd the parent RDD
param: partitioner partitioner used to partition the shuffle output
param: serializer Serializer to use. If not set
explicitly then the default serializer, as specified by spark.serializer
config option, will be used.
param: keyOrdering key ordering for RDD's shuffles
param: aggregator map/reduce-side aggregator for RDD's shuffle
param: mapSideCombine whether to perform partial aggregation (also known as map-side combine)