Thanks for the help namit ! :)
On Fri, Dec 24, 2010 at 12:00 PM, Namit Jain <nj...@fb.com> wrote: > Yes > > Sent from my iPhone > > On Dec 23, 2010, at 8:02 PM, "bharath vissapragada" > <bharathvissapragada1...@gmail.com > > wrote: > >> Hi, >> >> Thanks for the reply . >> >> This is the optimization of converting 2 MR jobs to a single MR job >> right ? as we are using only a single join val per table. >> >> Thanks >> Bharath.V >> 4th year undergraduate, >> IIIT Hyderabad, >> >> On Fri, Dec 24, 2010 at 12:22 AM, Namit Jain <nj...@fb.com> wrote: >>> The idea there is to merge the join trees. >>> >>> For eg. If the query is: >>> >>> Select * from >>> T1 join T2 on T1.key = T2.key >>> join T3 on T1.key = T3.key >>> Where ... >>> >>> >>> One join can have 3 inputs: T1, T2 and T3. >>> >>> mergeJoinTree() merges the 2 join operators (T1,T2) and (result of >>> (T1,T2), T3) >>> into a new join operator with 3 children (T1,T2,T3) >>> >>> >>> On 12/23/10 4:24 AM, "bharath vissapragada" >>> <bharathvissapragada1...@gmail.com> wrote: >>> >>>> Hi all, >>>> >>>> >>>> Once the JoinTrees are created by the the semantic analyzer for a >>>> query block , a function mergeJoinTree(qb) is called . >>>> Can anyone tell me what it does ? >>>> >>>> Thanks in anticipation, >>>> Bharath.V >>> >>> >
