Graeme Hinchliffe <graeme.hinchliffe@xxxxxxxxxxxxxxxxx> writes: > If I do the following: > SELECT username,acctstarttime FROM radacct WHERE username='user' > ORDER BY acctstarttime; > again the results come up slightly slower as would be expected but > still very quickly.. (a few hundred rows in this case) > Now, if I do the following: > SELECT username,acctstarttime FROM radacct WHERE username='user' > ORDER BY acctstarttime LIMIT 50; > I have to wait a very long time, IE instead of 2-3 seconds.. can be > as slow as 10+ minutes. Have you compared EXPLAIN ANALYZE outputs for the two cases? Presumably the planner is picking a different plan for the LIMIT case (and guessing wrong :-() regards, tom lane
