[postgis-users] relationship functions not working well

[William Kyngesburye]

On Dec 5, 2008, at 11:22 AM, Martin Davis wrote:

> Good news!  I thought about this some more overnight, and I realized  
> that the relation "interior-intersects" should produce the result  
> you're looking for.  This still doesn't have a named predicate, but  
> the really good news is that the IM pattern for this is trivial:   
> [T********] .
>
> (Exercise left for the student: Prove that the pattern expression  
> for "intersects-and-not-touches"  is equivalent to [T********].  Or  
> not - the proof in either situation would be interesting)


Well, that works:

ST_relate(wkb_geometry, SetSRID('BOX3D(-162 55,-161 56)'::box3d,4326),  
'T********')

But it's painfully slow - looks like relate doesn't do an index  
bounding box test.

... added a normal intersect (it's a superset of what I want) and let  
short-circuit logic take care of the initial selection:

ST_Intersects(wkb_geometry, SetSRID('BOX3D(-162 55,-161 56)'::box3d, 
4326)) AND ST_relate(wkb_geometry, SetSRID('BOX3D(-162 55,-161  
56)'::box3d,4326), 'T********')

That's reasonably fast, for a small box at least.  It will likely slow  
down on a larger box.

-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/

"Those people who most want to rule people are, ipso-facto, those  
least suited to do it."

- A rule of the universe, from the HitchHiker's Guide to the Galaxy