Mikkel Lauritsen <renard@xxxxxxx> writes: > I would like to do a query which retrieves the newest record for each > type, and the persistence framework that I'm using does something > which is structurally like > SELECT * FROM table t1 WHERE 0 = (SELECT COUNT(*) FROM table t2 WHERE > t2.type = t1.type AND t2.timestamp > t1.timestamp) I suspect that *any* database is going to have trouble optimizing that. You'd be well advised to lobby the persistence framework's authors to produce less brain-dead SQL. The NOT EXISTS formulation seems to express what's wanted much less indirectly. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
