I found a slow part of the query:
SELECT
date(extract(YEAR FROM m.taken)||'-1-1') d1,
date(extract(YEAR FROM m.taken)||'-1-31') d2
FROM
climate.city c,
climate.station s,
climate.station_category sc,
climate.measurement m
WHERE
c.id = 5148 AND ...
date(extract(YEAR FROM m.taken)||'-1-1') d1,
date(extract(YEAR FROM m.taken)||'-1-31') d2
FROM
climate.city c,
climate.station s,
climate.station_category sc,
climate.measurement m
WHERE
c.id = 5148 AND ...
Date extraction is 3.2 seconds, but without is 1.5 seconds. The PL/pgSQL code that actually runs (where p_month1, p_day1, and p_month2, p_day2 are integers):
date(extract(YEAR FROM m.taken)||''-'||p_month1||'-'||p_day1||''') d1,
date(extract(YEAR FROM m.taken)||''-'||p_month2||'-'||p_day2||''') d2
What is a better way to create those dates (without string concatenation, I presume)?
Dave
