Bruno Baguette <bruno.baguette@xxxxxxxxx> writes: > Le 13/11/08 14:31, Tom Lane a écrit : >> 16.511 * 818 = 13505.998, so this is all but about 100 msec of the >> runtime. Can't tell if there's any easy way to improve it. In >> pre-8.4 releases trying to convert the EXISTS into an IN might help. > Can you explain why a IN is fastest than an EXISTS subquery ? The planner is smarter about IN than EXISTS --- it can usually convert the former into a join plan instead of a subplan. (This situation will improve in 8.4.) > Do you think I can improve again the performance of that query ? You've still got a subplan in there, not quite sure why. Anyway, increasing work_mem might get it to change to a hashed subplan, which'd likely be faster. 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
