Thanks for your reply Zheng ,
If no. of tables = no. of cols to be joined .. we can do it in one shot ! Got it! On Thu, Feb 4, 2010 at 3:05 AM, Zheng Shao <[email protected]> wrote: > https://issues.apache.org/jira/browse/HIVE-591 > > On Wed, Feb 3, 2010 at 1:34 PM, Zheng Shao <[email protected]> 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 > > <[email protected]> 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 >
