Tom Lane wrote:
Rajesh Kumar Mallah <mallah@trade-india.com> writes:
SELECT DISTINCT main.* FROM
( ( ( ( Tickets main JOIN Groups as Groups_1 ON ( main.id = Groups_1.Instance) ) JOIN Principals as Principals_2 ON ( Groups_1.id = Principals_2.ObjectId) ) JOIN CachedGroupMembers as CachedGroupMembers_3 ON ( Principals_2.id = CachedGroupMembers_3.GroupId) ) JOIN Users as Users_4 ON ( CachedGroupMembers_3.MemberId = Users_4.id)
) WHERE...
I think the reason for the performance difference is that 7.3 treats
JOIN syntax as forcing a particular join order, while 7.4 doesn't.
Just out of curiosity , how does 7.4 determine the optimal Join Order?
is it GEQO in case of 7.4 although i did not enable it explicitly?
Thanks for the reply , I sent the EXPLAINs also just now.
What i really want is to help improving the Pg specific Component
for DBIx::SearchBuilder. The module is being widely used in
the mod_perl world and has impact on the performance perception
of PostgreSQL.
regards, tom lane
