~300 million measurements ~12000 stations (not 70000 as I mentioned before) ~5500 cities
some serious data tho, at least. Basically, PG is sequentially scanning through all of the tables in your partitioning setup. What is constraint_exclusion set to? What version of PG is this? Do the results og this query look at all correct to you?
PG 8.4
show constraint_exclusion; partition
With so much data, it is really hard to tell if the query looks okay without having it visualized. I can't visualize it until I have the query set up correctly. At the moment it looks like the query is wrong. :-(
Have you considered an index on elevation, btw? How many records in that city table are there and how many are actually in that range?
I've since added a constraint on elevation; it'll help a bit:
CREATE INDEX station_elevation_idx ON climate.station USING btree (elevation);
