"Josh Berkus" <[EMAIL PROTECTED]> writes: > Tom, > >> Wasn't this exact proposal discussed and rejected awhile back? > > We rejected Greenplum's much more invasive resource manager, because it > created a large performance penalty on small queries whether or not it was > turned on. However, I don't remember any rejection of an idea as simple > as a cost limit rejection.
The idea's certainly come up before. It probably received the usual non-committal cold shoulder rather than an outright "rejection". > This would, IMHO, be very useful for production instances of PostgreSQL. > The penalty for mis-rejection of a poorly costed query is much lower than > the penalty for having a bad query eat all your CPU. Well that's going to depend on the application.... But I suppose there's nothing wrong with having options which aren't always a good idea to use. The real question I guess is whether there's ever a situation where it would be a good idea to use this. I'm not 100% sure. What I would probably use myself is an option to print a warning before starting the query. That would be handy for interactive sessions so you would be able to hit C-c instead of waiting for several minutes and then wondering whether you got the query wrong. I wonder if it would be useful to have a flag on some GUC options to make them not globally settable. That is, for example, you could set enable_seqscan in an individual session but not in postgres.conf. Or perhaps again just print a warning that it's not recommended as a global configuration. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's Slony Replication support! -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers