[OSM-dev] Ways with 40k nodes, was: osmosis pgsql schema

Stefan de Konink stefan at konink.de
Fri Oct 31 14:53:21 GMT 2008


Matt Amos wrote:
> On Fri, Oct 31, 2008 at 12:55 PM, Stefan de Konink <stefan at konink.de> wrote:
>> Andy Allan wrote:
>>> No, hang on, that would be daft. I'd be better off making subtrees
>>> limited to about 1000 nodes or thereabouts, to improve the efficiency
>>> of partial checkouts. So then I would have sensibly sized subtrees
>>> (lets call them 'ways') and the master super-tree (lets call it a
>>> relation).
>> You miss the point of rewriting ways into relations. It will reduce the
>> code complexity and database complexity of all operations significantly.
> 
> quick question: if your schema used ordered relations instead of ways,
> do you have an unordered relation type as well?

That is a client rendering issue. The order is maintained as how it is 
inserted with an explicit idx. If mapnik/geoserver doesn't care about 
order and it is just a bunch of nodes all being campingplaces, it is 
just that.

>> The amount of tables is reduced, that means the amount of joins are
>> reduced. And the indices required for database searches are now more
>> efficient. Queries therefore get shorter, no need for a specific way
>> renderer.
> 
> except when your relation doesn't relate linear features.

What do you mean with linear features? The relation still has the 
ability to relate nodes or a relations. So I don't really see what you mean.


Stefan




More information about the dev mailing list