Re: join selectivity

"Mark Cave-Ayland" <m.cave-ayland@webbased.co.uk> writes:

> Well at the moment PostGIS has a RESTRICT function that takes an expression
> of the form <column> <op> <constant> where column is a column consisting of
> geometries and constant is a bounding box. This is based upon histogram
> statistics and works well.

Are these functions that would be useful for GiST indexes in general? 

What's involved in pulling them into a system? I mean, for example, a database
using RTREE (or GiST I guess) boxes and the @ operator.

I didn't realize anyone really had any idea where to start with gathering
statistics or writing selectivity functions for geometric types. It's great
news to hear there's actually work in this area.

-- 
greg