NopMap wrote: > I read about them in the releasenotes when 0.7 was announced, but frankly I > don't understand how to use them / how they would help me. Could you explain > a little bit about the intended use?
!bbox! Normally, mapnik slaps a WHERE way && <bbox statement> at the end of the query you define in the Datasource. There are situations or complex SQL queries where you may want to do the filtering against the bbox at another place. It's hard to explain without going into a course on PostGIS, and I don't even understand a lot of that yet. !scale_denominator! This makes it possible to influence your SQL query (and resultset) depending on the zoom level being rendered. You could construct a query that only returns huge polygons at very low zooms, large polygons at medium zooms, and all polygons at high zooms. I do plan to play with these soon, so I can use these on osm.org once that updates to 0.7.0. I'll probably add these to the trac article on optimizations too. -- Lennard _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
