On Dec 14, 2012, at 3:36 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Evgeny Shishkin <itparan...@gmail.com> writes: >> On Dec 14, 2012, at 3:09 AM, Andrew Dunstan <and...@dunslane.net> wrote: >>> Well, it looks like it's choosing a join order that's quite a bit different >>> from the way the query is expressed, so the OP might need to play around >>> with forcing the join order some. > >> OP joins 8 tables, and i suppose join collapse limit is set to default 8. I >> thought postgresql's optimiser is not mysql's. > > It's not obvious to me that there's anything very wrong with the plan. > An 8-way join that produces 150K rows is unlikely to run in milliseconds > no matter what the plan. The planner would possibly have done the last > join step differently if it had had a better rowcount estimate, but even > if that were free the query would still have been 7 seconds (vs 8.5). >
May be in this case it is. I once wrote to this list regarding similar problem - joining 4 tables, result set are off by 2257 times - 750ms vs less then 1ms. Unfortunately the question was not accepted to the list. I spoke to Bruce Momjian about that problem on one local conference, he said shit happens :) > regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
