Simons SQL Blog

This is not entirely correct. STContains means that they can't share border. Calculating the intersection includes the border:

Compare these two queries:

declare @g geography = 'POLYGON((0 0,0 10,10 10,10 0, 0 0))';

declare @l geography = geography::Parse('LINESTRING(0 10,10 10)');

select @g.STIntersection(@l).STEquals(@l);

(return true)

declare @g1 geometry = 'POLYGON((0 0,10 0,10 10,0 10, 0 0))';

declare @l1 geometry =  geometry::Parse('LINESTRING(10 0,10 10)');

select @g1.STContains(@l1);

(returns false)

In general the problem with Geography is that Microsoft haven't implemented STRelate which is the generic method that all these operations use (granted this is hard for spherical geometry). Instead they patched it up with a couple specially implemented topological operations.

Actually, determining the Relation matrix itself is not a problem.  Instead, one big part of the problem is the definition of Boundary on the ellipsoid.  No OGC spec defines how an edge is defined on the earth (our resident mathematician, Michael Kallay, wrote a paper on the subject for ACM-GIS 2007 "Defining Edges on a Round Earth"

http://www.cise.ufl.edu/dept/acmgis2007/poster-sessions.html) and hence the boundary of these objects is not explicitly defined either.  So we did not implement any OGC relation operator that had an explicit requirement on the boundary of the object, nor did we expose the STBoundary method.

Новой возможностью SQL Server 11 в части геопространственных расширений являются агрегатные функции...