Le vendredi 27 novembre 2009 à 23:32:14, Jeff Amiel a écrit : > --- On Fri, 11/27/09, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > > You didn't show us any evidence of that, either. Both > > of your test > > cases are using the index. > > Ok...third try. The cost when passing in an empty string is SIGNIFICANTLY > higher than when not. Wouldn't seem that the planner is using the index > effectively. > > Aggregate (cost=231884.57..231884.57 rows=1 width=0) > > versus > > Aggregate (cost=34.83..34.83 rows=1 width=0) > But in the first example (the empty string one), it fetched 170468 rows from the index, and in the second one (the 17-spaces string), it fetched only 18 rows. It seems quite normal that the first one is costier then the second one. -- Guillaume. http://www.postgresqlfr.org http://dalibo.com -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
