[postgis-users] Performance comparison between PostGIS's topology creation and topojson (the module)

Sandro Santilli strk at keybit.net
Tue Mar 18 03:46:30 PDT 2014

On Tue, Mar 18, 2014 at 10:19:44AM +0100, Rémi Cura wrote:
> Hey,
> Sandro could you give more details about how postgis topology use
> PolygonizeGraph in GEOS?

It doesn't at all, GEOS graphs not being exposed to the C-API.
Would be an interesting project to expose them.
Probably the interfaces of those classes would also need to be
extended to allow for computing all the ISO relations.

> And how does it work when inserting/deleting/changing a line into the
> topology model regarding this geos topological graph?

The "graph" for postgis topology only exists on the database, with
no corresponding in-memory representation. So all changes happen
on disk, with the obvious overhead.


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