On Apr 30, 2011, at 7:38 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Pavel Stehule <pavel.steh...@gmail.com> writes: >> Actually we had to solve a issue with slow SELECT. The problem was in >> low value of JOIN_COLLAPSE_LIMITS. Can we increase a default of this >> value. I checked some complex query, and planner needed about 200ms >> for JOIN_COLLAPSE_LIMIT = 16. So some around 12 can be well. > > I'd like to see a rather larger survey of cases before changing that. > Also, amount of memory consumed is at least as large a concern here > as runtime.
I seem to remember that I was the last one to suggest raising these limits and someone demonstrated rather convincingly that for certain classes of queries that would cause really big problems. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
