On Fri, Mar 2, 2012 at 5:12 AM, Tyler Durden <tylersticky@xxxxxxxxx> wrote: > Hi, > I can't figure out why query planner doesn't use the proper index, anyone > can help me? > > This query properly uses indexes: > > mydb=# EXPLAIN SELECT U0."object_id" FROM "activity_follow" U0 WHERE > (U0."content_type_id" = 3 AND U0."user_id" = 1); Query plan: http://explain.depesz.com/s/ccJ No order by in the above. Order by in the below: > mydb=# EXPLAIN SELECT "activity_action"."id", "activity_action"."actor_id", > "activity_action"."verb", "activity_action"."action_content_type_id", > "activity_action"."action_object_id", > "activity_action"."target_content_type_id", > "activity_action"."target_object_id", "activity_action"."public", > "activity_action"."created", "auth_user"."id", "auth_user"."username", > "auth_user"."first_name", "auth_user"."last_name", "auth_user"."email", > "auth_user"."password", "auth_user"."is_staff", "auth_user"."is_active", > "auth_user"."is_superuser", "auth_user"."last_login", > "auth_user"."date_joined" FROM "activity_action" INNER JOIN "auth_user" ON > ("activity_action"."actor_id" = "auth_user"."id") WHERE > "activity_action"."actor_id" IN (SELECT U0."object_id" FROM > "activity_follow" U0 WHERE (U0."content_type_id" = 3 AND U0."user_id" = 1 )) > ORDER BY "activity_action"."created" DESC LIMIT 100; query plan: http://explain.depesz.com/s/f92O What happens if you drop the order by on it? Just for comparison. I'm guessing that needing to sort is where the cost is coming from. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
