* andrew@xxxxxxxxxxxx <andrew@xxxxxxxxxxxx> [20070728 21:05]: > Let's try putting the sort/limit in each piece of the UNION to speed them up separately. > > SELECT * FROM ( > (SELECT * FROM large_table lt > WHERE lt.user_id = 12345 > ORDER BY created_at DESC LIMIT 10) AS q1 > UNION > (SELECT * FROM large_table lt > WHERE user_id IN (SELECT contact_id FROM relationships WHERE user_id=12345) > ORDER BY created_at DESC LIMIT 10) AS q2 > ORDER BY created_at DESC LIMIT 10; It's not possible to use ORDER BY or LIMIT within unioned queries. http://www.postgresql.org/docs/8.2/static/sql-select.html#SQL-UNION Would that make sense at all given the way the postgresql planner works? Does that work in other DB's? Til ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
