[OSM-dev] mapnik style - datasources parameters

Lennard ldp at xs4all.nl
Thu Mar 3 23:32:38 GMT 2011

On 3-3-2011 21:12, Philipp Borgers wrote:

> is there any reason why the datasource parameters srid and
> geometry_field are not used in the actual mapnik style file for osm? If
> I add
> <Parameter name="srid">4326</Parameter>
> <Parameter name="geometry_field">way</Parameter>
> to every datasource the amount of requests goes down.

Did you only surmise that from the documentation or did you actually see 
this in your pglogs?

These geometry_field,srid queries are only done once per layer during 
the parsing of the stylesheet, and cached. In mod_tile scenarios this 
means these extra queries only happen once in weeks or months.

If you reload the stylesheet for every render request, then yeah, it 
could, maybe, make a difference.


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