[Maps-l] introduction: the new osm database

[Colin Marquardt]

2010/5/11 Peter Körner <osm-lists at mazdermind.de>:
> I'm proud to announce the availability of a new osm database that holds
> all nodes, ways and polygons with all used tags used in osm.

Thanks very much for working on this.

[...]
> To show the capabilities of the new hstore scheme in conjunction with
> the rendering system, I created a style that renders surveillance cctvs
> on a transparent overlay. It's a quite simple style but it shows how to
> do things. It's located at
> /home/project/o/s/m/osm/data/styles/surveillance/surveillance.xml and
> should be redable for everyone.

I used the one in your home directory, didn't see a styles directory
(neither as cmarqu nor as osm).

So, yeah, thanks to that example, I was able to successfully modify
the SQL select for one of the map features I use - one that likely
will come from hstore ("lit" that is). What's a bit special is that
I'm using cascadenik for my styles, and in general, that works ok.

However... with a Cascadenik style, you have an mml file where you
collect your SQL statements and define layers etc., and one or more
mss files where you define the actual styling of the map elements (in
a CSS-like syntax).

A simple mss element could look like this:
.area.lighting[lit=yes]{ polygon-fill: #ddc96a; }
You can also restrict things further though, like
.area.lighting[lit=yes][building!=yes]{ polygon-fill: #ddc96a; }
and there, things begin to break:

ERROR:  column "building" does not exist

I'm not sure what to do now. Even supposing Cascadenik can be modified
to support hstore selects (not by me for sure), this breaks the
separation of getting the data and styling the data, as you now have
to know *where* to get "building" from. I might as well switch to raw
Mapnik in that case.

Cheers
  Colin