subtractByKey
fun <K, V, W> JavaRDD<Tuple2<K, V>>.subtractByKey(other: JavaRDD<Tuple2<K, W>>): JavaRDD<Tuple2<K, V>>
Return an RDD with the pairs from this whose keys are not in other.
Uses this partitioner/partition size, because even if other is huge, the resulting RDD will be less than or equal to us.
fun <K, V, W> JavaRDD<Tuple2<K, V>>.subtractByKey(other: JavaRDD<Tuple2<K, W>>, numPartitions: Int): JavaRDD<Tuple2<K, V>>
fun <K, V, W> JavaRDD<Tuple2<K, V>>.subtractByKey(other: JavaRDD<Tuple2<K, W>>, p: Partitioner): JavaRDD<Tuple2<K, V>>
Return an RDD with the pairs from this whose keys are not in other.