[postgis-users] spatial index for topology?

[Sandro Santilli]

On Sat, Oct 26, 2013 at 06:27:41PM -0500, William Kyngesburye wrote:
> Is there any way to spatially index topogeometry?

Nope, due to the fact that TopoGeometry spatial extent is not
in the value itself but derived using a volatile function from
external (referenced) data.

This is a known problem:
http://trac.osgeo.org/postgis/ticket/2124
http://trac.osgeo.org/postgis/ticket/853

One idea would be to make the && operator be
implemented by an SQL-defined function to be
fully inlined and thus giving the planner enough
hints to use the index on the underlying primitive
tables, but feasibility of that is uncertain.

Another idea would be to introduce a trigger-based
mechanism to update some form of bbox cache into
each TopoGeometry affected by any change into any
primitive table, and then use that cache in select
querys. Note that making it transparent (using &&
operator) would require a change in the TopoGeometry
structure, to add a bounding box field. 

--strk;