[OSM-dev] Best way to select from a region

Roland Olbricht roland.olbricht at gmx.de
Tue Sep 1 10:35:31 BST 2009


> In 95% of cases you will find that the borders in the database are
> unsuitable because they do not form a proper closed polygon. Plus,
> PostGIS definitely sucks at point-in-polygon performance, especially if
> your polygon has 30k points.

There are currently at least 51090 correct boundary polygons (as of 2009-09-01 
03h00 UTC) in the database. I doubt that these are only 5% of all boundaries 
(would the be more than 1'000'000) in the OSM database - there aren't even a 
million relations at all.

Have you considered just downloading the list? If you don't want to have all 
the trouble with running a GIS database, you may directly use XAPI or OSM3S 
to obtain specific data in XML format from a region, see
http://wiki.openstreetmap.org/wiki/XAPI
http://wiki.openstreetmap.org/wiki/OSM_Server_Side_Script

Cheers,

Roland




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