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

Luca Morandini lmorandini at ieee.org
Mon Mar 17 13:34:37 PDT 2014

On 17/03/14 23:36, Rémi Cura wrote:
> If you _know_ that your data is topological ready (no intersection).
> You can  fill the topology table way faster using set query (rather than the
> actual line by line algorithm).
> the first step would be to compute the pair of all connected segments, then
> extract from it node, node-segment relation and segment-segment relation. Then fil
> the face table with bbox from enveloppe of lines
> Yet it would require to write some dedicated sql.

I see your point, but, apart from complexity, I was a little bit worried by the 
number of schemas to create while seeding the cache using PostGIS (every tile a 
topology, hence every tile a schema): doing it in Node.js looks a safer bet.

> Another solution (experimental) would be to load your geometry as a GRASS GIS
> vector layer, then use the Grass method (grass 7 only) to convert it to
> postgis_topology.
> It should be way way faster.

Using the topojson module is way handier.


Luca Morandini
Data Architect - AURIN project
Melbourne eResearch Group
Department of Computing and Information Systems
University of Melbourne
Tel. +61 03 903 58 380
Skype: lmorandini

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