One-to-multiple lookup

[liyan2015]

Hi, Ankur,

IndexedRDD works prefect for one-to-one Key-Value pairs. But for the case that there are multiple values to a key, it only returns one value, which is not as the Seq(Value) returned by lookup method of RDD.

Since IndexedRDD extends from RDD, I guess perhaps the lookup method is worth overriding? Or its one-to-multiple lookup performance will be actually the same with the one for RDD partitioned by HashPartitioner? Thanks for your patience.

Best regards,
Li