Partitioner
Related Docs:
class Partitioner
| package spark
Choose a partitioner to use for a cogroup-like operation between a number of RDDs.
Choose a partitioner to use for a cogroup-like operation between a number of RDDs.
If any of the RDDs already has a partitioner, choose that one.
Otherwise, we use a default HashPartitioner. For the number of partitions, if spark.default.parallelism is set, then we'll use the value from SparkContext defaultParallelism, otherwise we'll use the max number of upstream partitions.
Unless spark.default.parallelism is set, the number of partitions will be the same as the number of partitions in the largest upstream RDD, as this should be least likely to cause out-of-memory errors.
We use two method parameters (rdd, others) to enforce callers passing at least 1 RDD.