"news.gmane.org" <nis@xxxxxxxxxxxxx> writes: > Gurjeet Singh skrev: >> Also note that this query is much cheaper that the 'distinct on' query >> by more than two orders on magnitude ( 217.86 vs. 98040.67): > No it isn't. The estimate is much lower, but the actual times are very > close: > [explain of distinct on] >> Time: 5.003 ms > [explain of correlated subquery] >> Time: 4.125 ms You're both confused: the planner estimate certainly should not be taken as gospel, but the actual runtime of an EXPLAIN (not EXPLAIN ANALYZE) only reflects planning effort. EXPLAIN ANALYZE output would be a lot more suitable to settle the question which one is faster. regards, tom lane
