I wasn't involved in this decision ("I just make the fries"), but
CompactBuffer is designed for relatively small data sets that at least fit
in memory. It's more or less an Array. In principle, returning an iterator
could hide the actual data structure that might be needed to hold a much
bigger data set, if necessary.HOWEVER, it actually returns a CompactBuffer. https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala#L444 Dean Wampler, Ph.D. Author: Programming Scala, 2nd Edition <http://shop.oreilly.com/product/0636920033073.do> (O'Reilly) Typesafe <http://typesafe.com> @deanwampler <http://twitter.com/deanwampler> http://polyglotprogramming.com On Thu, Apr 23, 2015 at 5:46 PM, Hao Ren <inv...@gmail.com> wrote: > Should I repost this to dev list ? > > > > -- > View this message in context: > http://apache-spark-user-list.1001560.n3.nabble.com/why-does-groupByKey-return-RDD-K-Iterable-V-not-RDD-K-CompactBuffer-V-tp22616p22640.html > Sent from the Apache Spark User List mailing list archive at Nabble.com. > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@spark.apache.org > For additional commands, e-mail: user-h...@spark.apache.org > >
