[OSM-talk] Relations not always brilliant

Frederik Ramm frederik at remote.org
Mon Apr 7 11:11:12 BST 2008


Hi,

> But this is kind of the point - if you are able to automatically  
> create the relations (and presumably automatically fix them if  
> someone makes the way tags inconsistent with the relation tags)  
> with very little effort, is there a good reason to create them in  
> the first place rather than deriving that data as and when you need  
> it?

I assume it will usually be easier to check a machine-readable  
relation than to compare tags. A grouping relation is a more abstract  
thing and can be used for other purposes (i.e. many ways might  
together make up the "city bypass", but this might not depend on the  
road "ref" but on the road name). I assume that anyone working with  
the data in earnest will have to support relations anyway, so it  
seems unnecessary to ask them to also group by tags which involves  
finding out which tags to group by, which bounding box so search in,  
splitting tag values at semicolons etc.

Rather than have one million systems implement their own ways of  
guessing what was meant, I'd like to put this explicitly in the  
database (or at least have *one* central system do the grouping  
consinstently).

But this discussion is becoming much too theoretical. Let's just do  
what works. You use the ref tags on individual objects, and if at any  
point in time I see the need for relations generated on the basis of  
these then I can generate them.

My original point "why not get used to it now" is perhaps the more  
important one; we're still very much at the beginning concerning  
relations and the more people get exposed to relations, the better  
we'll be able to work with them and use them productively.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"







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