[postgis-users] Point in Polygon query tolerance?

Michael Fuhr mike at fuhr.org
Sun Aug 5 08:48:57 PDT 2007


On Sun, Aug 05, 2007 at 12:00:28PM +0200, Frank Broniewski wrote:
> Am Samstag, 4. August 2007 schrieb Michael Fuhr:
> > The && operator is a fast check for bounding box overlaps that can
> > take advantage of indexes.  You'll need to restrict the result set
> > further by adding a more expensive test like one of the following:
> >
> > contains(c.the_geom, p.op_centroid)
> > within(p.op_centroid, c.the_geom)
> > intersects(c.the_geom, p.op_centroid)
> > distance(c.the_geom, p.op_centroid) = 0
> 
> Thanks alot for your tip, now I get the correct results. One more thing 
> though. I was looking for operators like contains and such already, but I 
> wasn't able to find them literally in the manual. Am I correct, when I assume 
> that these operators are listed in Chapter 6 and have a "ST_" prefix ( 
> http://postgis.refractions.net/docs/ch06.html )? Because my postgis version 
> does not know them. But since I installed postgis on my ubuntu machine using 
> apt-get, I presume I have a quite outdated version.

The online doc is for the version currently under development.  As
the Note at the top of Chapter 6 indicates, most functions have
been renamed to have the ST prefix but the functions without the
prefix will still be available.  Older versions -- including the
most recent stable release -- use the function names without the
ST prefix.

-- 
Michael Fuhr



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