The countries are not a problem. But usually you don't want blank data right after the state border, that's the point.

The way it works currently makes me think those people are right. It issues a bloody heavy SQL query to the GIS for every 256 by 256 tile. I suspect that rendering a 2048x2048 tile in one go and then cut it into 64 256x256 tiles (think multiprocessing, again) would be far more efficient, but trying this requires quite a bit of time I don't have at the moment.

I also have this idea of using a clustered setup. I also don't want my Twisted knowledge to rust. The company I'm working at announced an R&D lab for noncommercial, spinoff and hobby projects, so maybe someday I would talk them into building the most efficient OSM rendering farm in the world.

Seeing demise of t@h, OTOH, I'm a bit skeptical about this one.

I don't know a thing about layers. All tiles are single layer, with all details already burnt-in. The point is that in OSM default stylesheet has better contrast overall, and maps rendered with it have proper city/village/whatever boundaries rendered, which my maps don't.

Let me reiterate a bit.

OSM works generally by building a geospatial database out of its input files, and schemas can be designed in different ways. The xml styles for maps are tuned to a particular schema, containing all the queries. The osm.xml shipped with Mapnik is tuned to their own database schema as produced by osm2pgsql tool, which either is dog slow or requires gobs of memory (8 GiB is way too small for Poland, let alone Europe).

imposm, on the other hand, handles data much more efficiently on your average desktop/laptop hardware, my humble entry-level Thinkpad would crunch all of Europe in around 4 hours which is fast. The problem is, tables, tags and so on as produced by this tool, are totally different from what osm2pgsql provides.

So, in fact, I had to google "imposm osm.xml style compatible" and so on, getting irrelevant things at the top, until I've found OSM-bright and Carto. Then, the stylesheet produced makes what you see on the screenshot.

The OSM XML is so big that I don't have the faintest idea what to tweak so it would work.

Or maybe I would leave osm2pgsql running for a weekend with the latest Europe data, set up a cron job to incorporate differences as they flow in (osm2pgsql data allow this, imposm don't, AFAIK), and then render particular countries (so they have consistent data at the borders and so that anyone would be able to merge tilesets as he wishes).