On Fri, May 30, 2003 at 11:31:23 -0700, Stephan Szabo <[EMAIL PROTECTED]> wrote: > On Fri, 30 May 2003, Bruno Wolff III wrote: > > > I was hoping the new stuff Tom added would make doing this easier. The issue > > has come up before and at least at that time it didn't get changed so I > > expected it wasn't easy to do. > > > > I thought maybe there was information for the - operator > > that would allow you to know that you could use an index on -col > > to go in the reverse direction safely. > > Not really. I think that if you were to do that, you'd probably need to > provide an additional thing to the opclass to let it know. Otherwise it'd > be unsafe for user defined types/user defined - operators and doesn't help > on things where - isn't the correct way to do it.
I went back and reread the stuff on NEGATOR and found it only applies to operators that return boolean types. I had thought it was different and would let you make the deduction a > b <=> -a <= -b, but that isn't the case. Instead it lets you make the deduction that a > b <=> NOT (a <= b). ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
