[OSM-talk] live rendering

[Schuyler Erle]

* On  3-May-2007 at  9:07AM PDT, Robert (Jamie) Munro said:
> 
> It is a solved problem. See http://labs.metacarta.com/osm. We just have
> to get updates into it as they happen, rather than once a week. PostGres
> triggers (or rules) are almost certainly capable of doing this.

Luka Frelih points out to me via private email that PostgreSQL also
supports notifications, which offers interesting possibilities. I
would be very very glad to work on setting up the labs.metacarta
tiling system to pull live updates from the main server.

> I'm sure improvements can be made. I'm mainly posting this stuff to
> avoid duplication of effort. Schuler is working on moving the DB to
> PostGIS and writing the triggers. I'm hoping to pick up his DB and port
> the rails port to it at the Oxford Dev meeting on Saturday (unless he
> does that first).

I don't think I'm going to get to it sooner, but my working materials
are online at http://freemap.in/~sderle/pg_osm/. Don't forget to
UTF8sanitize your planet.osm before piping it to import_osm.py.

> The next stage is to integrate Schuler's DB layout with Mapnik.

This is going to be a bit tricky, since Mapnik (I think) expects a
much flatter database structure than the Rails port uses. I have a
scheme in mind for mimicking this structure on the fly with a mesh of
views, rules, and indexes built on procedural functions but I haven't
tested it and can't yet say how it will perform. Certainly we can
maintain summary tables with triggers if it comes to that; Christopher
Schmidt and I have tested this on our own databases and it does work.

One thing at a time, though :)

SDE