Hi, Alexey.
Is it necessary to get the data as far as 1900 all the time ? Maybe there is a possibility to aggregate results from the past years if they are constant.
This I have done. I created another table (station_category) that associates stations with when they started to take measurements and when they stopped (based on the data in the measurement table). For example:
station_id; category_id; taken_start; taken_end
1;4;"1984-07-01";"1996-11-30"
1;5;"1984-07-01";"1996-11-30"
1;6;"1984-07-01";"1996-11-10"
1;7;"1984-07-01";"1996-10-31"
This means that station 1 has data for categories 4 through 7. The measurement table returns 3865 rows for station 1 and category 7 (this uses an index and took 7 seconds cold):
station_id; taken; amount
1;"1984-07-01";0.00
1;"1984-07-02";0.00
1;"1984-07-03";0.00
1;"1984-07-04";0.00
The station_category table is basically another index.
Would explicitly sorting the measurement table (273M rows) by station then by date help?
Dave