https://issues.apache.org/jira/browse/HIVE-591
On Wed, Feb 3, 2010 at 1:34 PM, Zheng Shao <zsh...@gmail.com> wrote: > See ql/src/test/queries/clientpositive/uniquejoin.q > > > FROM UNIQUEJOIN PRESERVE T1 a (a.key), PRESERVE T2 b (b.key), PRESERVE > T3 c (c.key) > SELECT a.key, b.key, c.key; > > FROM UNIQUEJOIN T1 a (a.key), T2 b (b.key), T3 c (c.key) > SELECT a.key, b.key, c.key; > > FROM UNIQUEJOIN T1 a (a.key), T2 b (b.key-1), T3 c (c.key) > SELECT a.key, b.key, c.key; > > FROM UNIQUEJOIN PRESERVE T1 a (a.key, a.val), PRESERVE T2 b (b.key, > b.val), PRESERVE T3 c (c.key, c.val) > SELECT a.key, a.val, b.key, b.val, c.key, c.val; > > FROM UNIQUEJOIN PRESERVE T1 a (a.key), T2 b (b.key), PRESERVE T3 c (c.key) > SELECT a.key, b.key, c.key; > > FROM UNIQUEJOIN PRESERVE T1 a (a.key), T2 b(b.key) > SELECT a.key, b.key; > > > Zheng > > On Wed, Feb 3, 2010 at 2:07 AM, bharath v > <bharathvissapragada1...@gmail.com> wrote: >> >> Hi , >> >> Can anyone give me an example in which there is an optimization of >> "Converting multiple joins into a single multi-way join" .. i.e., reducing >> the number of map-reduce jobs . >> I read this from hive's design document but I couldn't find any example . >> Can anyone point me to the same?? >> >> Kindly help, >> >> Thanks >> > > > > -- > Yours, > Zheng > -- Yours, Zheng
