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

Stefan de Konink stefan at konink.de
Fri Oct 31 16:06:51 GMT 2008

Matt Amos wrote:
> On Fri, Oct 31, 2008 at 3:19 PM, Stefan de Konink <stefan at konink.de> wrote:
>> Matt Amos wrote:
>>> would you represent a Y-shaped road as three relations, then? one for
>>> the left fork, one for the right stem as a way-relation, then another
>>> to group them together?
>> Yes, but with role='independent'. Otherwise the idx of the subtrees would
>> create a pyramid shape.
> i don't understand what you mean by a pyramid shape. the relations
> would be returned in the same order, regardless of the role tag,
> right? and you're not merging subtrees...?

My proposal would be merging subtrees, so they can store an highway with 
80km/h 100km/h zones in one relation as part of two subtrees (as 
optimalisation), or multiple subtrees for each zone found.

>>> when you say "no need for a specific way renderer" - there is still a
>>> need, as (in your example) you wouldn't want to render a bunch of
>>> camping nodes as a linear feature. you'll also want to render
>>> buildings filled. in other words: there isn't a single, specific way
>>> renderer anyway because tag inspection is required.
>> ... snip...
>> In the first version of the RelationOSM thing I created the same thing in
>> the relationship code, when the api 0.5 was used. If the tag way=true was
>> present, it would be rendered as <way><nds/></way>.
> exactly; you do tag inspection. doesn't that require an extra join to
> distinguish ways from relations of nodes?

That join is always done in order to produce tags related to the 
node/relation. But I see your point.


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