[OSM-talk] TileMill performance

[AJ Ashton]

Hi Steve,

> (eg, is [zoom>13] { #ways[...] } slower/faster than #ways[...][zoom>13] ?)

Does your layer setup actually looks like this? ie. one 'ways' layer
pulling in the entire planet_osm_ways table? If so this will be
problematic. Unlike MapCSS, filtering out objects with CartoCSS will not
prevent them from being loaded. With Mapnik/TileMill you should be querying
specific thematic subsets of the database for each layer.

The layer setup plays an important role in performance, so knowing what
that looks like in detail (number of layers, their contents, file/database
type database queries, projections, etc) would help track down potential
issues.

> Does setting a layer invisible definitely prevent it being computed?

TileMill/Mapnik will still check that hidden layers are valid each time the
project is saved/loaded, however that is the only thing it will do. These
layers shouldn't affect

--
AJ Ashton
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