2010/3/31 Ľubomír Varga <luvar@plaintext.sk>:
> Hi, stright to my "problem":
> If I try to select constant 1 from table with two rows, it will be something
> like this:
>
> explain
> SELECT * FROM t_route
> WHERE t_route.route_type_fk = (SELECT id FROM t_route_type WHERE type = 2)
> limit 4;
>
> "Limit (cost=1.02..1.91 rows=4 width=2640)"
> " InitPlan"
> " -> Seq Scan on t_route_type (cost=0.00..1.02 rows=1 width=8)"
> " Filter: ("type" = 2)"
> " -> Seq Scan on t_route (cost=0.00..118115.25 rows=535090 width=2640)"
> " Filter: (route_type_fk = $0)"
>
Looking at this it looks like you're using prepared queries, which
can't make as good of a decision as regular queries because the values
are opaque to the planner.
Can you provide us with the output of explain analyze of that query?