what is the fastest function in RDD spark -

i'm implementing groupby function , "transformations" operation.

i need groupby function must computed immediately, i've found out solution calling "action" likes first() or count() operation after groupby computed.

the running time of groupby equal + action operation, , need fastest function minimum total running time!!

thanks!

i assume doing performance testing kind of thing.so if right don't matter action returns,you need transformation(groupby) executed.
i think first() fastest rdd action can think of.

another approach can find time taken transformation(group by) alone in webui of spark.so can use rdd action wish!