[Talk-GB] Drinking Map of UK

[Jonathan Bennett]

On 05/11/2011 21:48, Graham Jones wrote:

> I know that tagging for the renderer is frowned upon, but I really do
> not like all these colons in key names, because (as far as I know) that
> means having an extra column in the database produced by osm2pgsql for
> rendering....and every time I want to add an extra column it means an
> entire re-import of the databse.

I don't claim to be an osm2pgsql expert, but I think that's a 
misunderstanding of the situation. I think *any* new tag added to 
osm.xml results in an extra column, whether it has a colon or not.

Generally you shouldn't consider any performance implications when 
creating a tag, because you don't know what will change in the next 
version of the code. The 
easy-for-mappers-but-maybe-a-bit-computationally-intensive scheme you're 
trying to avoid may become a non-issue with a few lines of code changed. 
Equally the opposite may happen.

For information, I'm assured that extra columns produce next to no 
performance degradation anyway since osm2pgsql started using hstore.

Jonathan.