[postgis-devel] Exclusion Constraints in PostgreSQL 8.5

Jeff Davis pgsql at j-davis.com
Tue Dec 8 12:38:01 PST 2009

On Tue, 2009-12-08 at 10:10 -0800, Paul Ramsey wrote:
> Is there any big advantage to exact-operator-with-recheck over doing
> inexact-operator-combined-with-exact-function-in-sql? Being able to do
> Exclusion Constraints would be one :) Are there others?

I have some rough sketches for other features that PostGIS might find
useful (a merge join that can work on "overlaps" rather than equals),
and that will also require the operators to have real meaning by
themselves. I won't promise it in 8.5 though.

In general, I think it's a good idea for the operators to have real
meaning -- that's largely what differentiates operators from functions
(at least in PostgreSQL; I'm not suggesting there's any mathematical

Of course, many people may find the current definitions useful as well,
but I assume that a lot of people want to know whether the geometries
themselves overlap.

	Jeff Davis

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