Re: Comments on Exclusion Constraints and related datatypes

On Mon, 2010-03-22 at 10:32 -0500, Kevin Grittner wrote:
> Simon Riggs <simon@2ndQuadrant.com> wrote:
> > On Mon, 2010-03-22 at 10:13 -0400, Tom Lane wrote:
> >> Simon Riggs <simon@2ndQuadrant.com> writes:
>  
> >> > * Circles, Boxes and other geometric datatypes defined
> >> > "overlaps" to include touching shapes. So
> >> > SELECT circle '((0,0), 1)' && circle '((2,0),1)';
> >> > is true, which is fairly strange and makes those datatypes very
> >> > counter intuitive. Considering they are instructional aids,
> >> > this is bad.
> >> 
> >> You're approximately twenty years too late to propose changing
> >> that, even if it were clearly a good idea which I doubt.
> > 
> > Possibly. We should at least document that.
>  
> Basically, what you feel is missing is documentation that if two
> shapes share one or more points they are considered to overlap;
> there is no requirement that they share an area?

Yes, for most people touching != overlap. So it just looks like a bug.

-- Simon Riggs           www.2ndQuadrant.com