I am trying to understand the working of REDUCE operator in hive. As mentioned in one of the docs "both MAP and REDUCE are "syntactic sugar" for the more general select transform" does it mean REDUCE applies only on the local batch-data ( acting only as "local-reduce" ) or they do act on the entire values for a particular key ? For MAP command its ok, as its ok for them to act only on a subset of the data. But for REDUCE semantics to work it has to act on the entire set of values for that particular key.
Let me know if I have misunderstood any of the semantics. -Thanks, Prasen
