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Re: query not using index for descending records?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
Cc: Bruno Wolff III <bruno(at)wolff(dot)to>,Achilleus Mantzios <achill(at)matrix(dot)gatewaynet(dot)com>,email lists <lists(at)darrenmackay(dot)com>, pgsql-sql(at)postgresql(dot)org
Subject: Re: query not using index for descending records?
Date: 2004-01-29 17:24:14
Message-ID: 24411.1075397054@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-sql
Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)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

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