On Wed, Jan 11, 2006 at 11:33:23PM -0500, Tom Lane wrote: > Mark Liberman <[EMAIL PROTECTED]> writes: > > I've got a set-returning function, defined as STABLE, that I reference > > twice > > within a single query, yet appears to be evaluated via two seperate > > function > > scans. > > There is no guarantee, express or implied, that this won't be the case. > > (Seems like we just discussed this a couple days ago...)
Well, from 32.6: "This category allows the optimizer to optimize away multiple calls of the function within a single query." That could certainly be read as indicating that if the function is used twice in one query it could be optimized to one call. Is the issue that the optimizer won't combine two function calls (ie: SELECT foo(..) ... WHERE foo(..)), or is it that sometimes it won't make the optimization (maybe depending on the query plan, for example)? -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
