Re: query not using index for descending records?

Stephan Szabo <sszabo@megazone.bigpanda.com> writes:
> I'd thought that I'd previously sent a message containing a set of
> definitions for the reverse opclasses (not meant for inclusion to the
> system because I was making SQL functions that basically did -<normal
> comparison function> to use as the function of the operator class, but
> possibly worth playing with) but now that I actually search again, I don't
> see it.

I don't recall having seen such a thing go by...

I fear that using SQL functions as comparators would only be useful for
proof-of-concept, not as an industrial-strength implementation.  The
index code needs comparator functions not to leak memory, and I doubt
that that could be guaranteed with a SQL function.  You'd probably have
speed issues too.
        regards, tom lane