If the join key is the same, you can use "unique join" to make sure it's done in a single map-reduce job.
Zheng On Wed, Feb 3, 2010 at 1:25 AM, bharath v <[email protected]> wrote: > Hi , > > I have a small doubt in how hive handles queries containing join of more > than 2 tables . > > Suppose we have 3 tables A,B,C .. and the plan is "((AB)C)" .. > We can join A,B in a map reduce job and join the resultant table with "C". I > have a doubt whether the result of "AB" is stored to disk before joining > with C or is it streamed directly to join with C (I don't know how , just a > guess) . > > > Any help is appreciated , > > Thanks -- Yours, Zheng
