Utility used to group data by key within RDD partitions by a key, assuming that RDD is already partitioned and sorted by key.
Utility used to group data by key within RDD partitions by a key, assuming that RDD is already partitioned and sorted by key. The RDD data are processed sequentialy without shuffling and materializing them in memory.
Expression to extract key from a value.
RDD with key -> values.
Maps RDD preserving partitioning