On Tue, 27 Apr 2004 18:01:34 -0400, Rod Taylor <[EMAIL PROTECTED]> wrote: >On Tue, 2004-04-27 at 17:27, Vitaly Belman wrote: >> Hello pgsql-performance, >> >> I discussed the whole subject for some time in DevShed and didn't >> achieve much (as for results). I wonder if any of you guys can help >> out: >> >> http://forums.devshed.com/t136202/s.html
>The point is that a book cannot be of a certain genre more than once. Rod, he has a hierarchy of genres. Genre 1 has 6379 child genres and a book can be in more than one of these. Vitaly, though LIMIT makes this look like a small query, DISTINCT requires the whole result set to be retrieved. 0.7 seconds doesn't look so bad for several thousand rows. Did you try with other genre_ids? Maybe a merge join is not the best choice. Set enable_mergejoin to false and see whether you get a (hopefully faster) hash join, assuming that sort_mem is large enough to keep the hash table in memory. If you send me your table contents I'll try it on Linux. Servus Manfred ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
