> -----Original Message----- > From: pgsql-general-ow...@postgresql.org [mailto:pgsql-general- > ow...@postgresql.org] On Behalf Of Tom Lane > Sent: Saturday, July 21, 2012 5:48 PM > To: David Johnston > Cc: pgsql-general@postgresql.org > Subject: Re: [GENERAL] A Better Way? (Multi-Left Join Lookup) > > I wrote: > > "David Johnston" <pol...@yahoo.com> writes: > >> So, > >> EXPLAIN SELECT function_call(...) -- yields a planner expectation of > >> 1 row [Whereas] EXPLAIN SELECT * FROM function_call(...) -- yields a > >> planner expectation of "result_rows" which defaults to 1000 > > > Hm ... > > >> Was this an intentional design decision to override the result_rows > >> estimate of the function if it is used in the select list? > > > Not so much an intentional decision as just that nobody ever did > > anything about it. > > I've now done something about that for 9.2. I'm loath to back-patch it into > any already-stable releases, though, for fear of destabilizing plan choices that > production applications might be relying on. > > regards, tom lane >
Understood and agree. It isn't like the proper estimates cannot be gotten - it just is less than syntactically beautiful to do so. Maybe a documentation patch instead of a code patch would be in order to at least give people of chance to learn about the inconsistent behavior before it bites them in 8.3 to 9.1? For me personally I read and learned about the function row estimate property and didn't make the connection between the fact I knew I was using the default of 1000 and the planner was telling me it was only using 1. Thank you for your responsiveness on this. David J. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
