[OSM-dev] Questions on PostGIS

Jochen Topf jochen at remote.org
Wed Feb 6 14:19:50 GMT 2008

On Wed, Feb 06, 2008 at 02:35:57PM +0100, Frederik Ramm wrote:
> > Basically I think it would be best to write a script that will  
> > generate
> > REAL ways (polylines) in the postGIS database in a real geometric  
> > table.
> > That way you will take optimized use of geometry functions.
> I assume that this might use up a lot of space, and it might be  
> viable to store a bounding box with each way instead of a proper  
> polyline. This would lead to some "false positives" (if a way's  
> bounding box intersects with your query bounding box, this does not  
> always mean that the way does) but could save time and space.

PostGIS is very space efficient as it stores the polyline in some
binary format. And if the polylines are used there are many nice
operations that PostGIS gives you for free, such as intersection between
ways etc.

If you want to optimize for space I suggest starting with the tags.
Storing the same string millions of times isn't that space efficient.

Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298

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