On Fri, 3 Mar 2006, Tom Lane wrote: > Stephan Szabo <[EMAIL PROTECTED]> writes: > > On Thu, 2 Mar 2006, Tom Lane wrote: > >> 1. If the index opclass contains an exact operator for the case > >> "PKtype = FKtype", use that operator. > > > Is this rule to read explicitly naming '=' or just the item in that > > position in the opclass? > > The operator occupying the equality position in the opclass.
Okay. > > I think it's an acceptable idea to fail if we're going to extend the > > cross-type indexing support, but AFAICS we have to at the very least allow > > all of the "standard" numeric types in all combinations to work to meet > > the spec, and I don't think the above rules and current opclasses will > > give that to us (and I don't honestly understand some of the bits of this > > to know if there's a problem with extending the opclasses to allow that). > > The cases that are likely to be problematic are things like a FLOAT8 > column referencing a NUMERIC primary key. However, that sort of > mishmash is fraught with all kinds of risks anyway (think roundoff > error) so the fact that the spec nominally allows it doesn't tell me > that we ought to encourage it. There's a bit of difference between not encouraging it and disallowing it entirely, but I'm willing to buy that argument. I do think that numeric reference int needs to be allowed though, and I thought that's also currently not there (although int reference numeric should work I think). ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match