[OSM-dev] Porting the mapnik stylesheet to carto

[Andy Allan]

On 16 November 2012 17:04, Matt Williams <lists at milliams.com> wrote:

> Great work. Do you have any idea how/if the performance changes when
> using Carto rather than the old XML?

In my experience it makes no appreciable difference. Carto compiles
down to XML, and usually most of the speed is in the sql queries and
the time taken by mapnik to draw things, rather than anything else.

However, it's reasonably easy in Carto to write some CSS that compiles
into pathological XML stylesheets, and they of course take ages to
parse and have a runtime impact too. I can make 20 lines of carto
compile into 20,000 lines of XML[1], but I also know how to avoid
doing that too :-)

However, my view is always that servers are cheap, cartographers are
thin on the ground, and (with reason) it's not worth worrying too much
when they are within a few percent of one another. I'd be interested
to see benchmarks if anyone fancies doing it, but my finger-in-the-air
would be the carto-generated XML will be within 10% of the
hand-crafted stuff since the bulk of it is the same.

Cheers,
Andy

[1] https://github.com/mapbox/carto/issues/20