On 29 Jan 2010, at 1:56, Yan Cheng Cheok wrote: > Isn't the primary constraint will implicitly create an index for day already? > > PRIMARY KEY (advertiser_id, day), Yes, but it's not a very efficient index to look for values of day if you don't provide a value for advertiser_id as well. See http://www.postgresql.org/docs/8.4/interactive/indexes-multicolumn.html Alban Hertroys -- If you can't see the forest for the trees, cut the trees and you'll see there is no forest. !DSPAM:737,4b62d2e810751877882363! -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general