Re: full outer performance problem

Kim Bisgaard <kib+pg(at)dmi(dot)dk> writes:
> I have two BIG tables (virtually identical) with 3 NOT NULL columns
> Station_id, TimeObs, Temp_XXXX, with indexes on (Station_id, TimeObs)
> and valid ANALYSE (set statistics=100). I want to join the two tables
> with a FULL OUTER JOIN.

I'm confused. If the columns are NOT NULL, why isn't this a valid
transformation of your original query?

> select temp_max_60min,temp_dry_at_2m
> from station s natural join
> temp_dry_at_2m a full outer join temp_max_60min b using (station_id, timeobs)
> where s.wmo_id=6065
> and _a.timeobs='2004-1-1 0:0:0' and b._timeobs='2004-1-1 0:0:0'
> and '2004-1-1 0:0:0' between s.startdate and s.enddate;

Seems like it's not eliminating any rows that would otherwise succeed.

regards, tom lane