[OSM-talk] conclusions from my postgres / postgis experiments

[SteveC]

* @ 23/11/06 09:23:22 AM sxpert at sxpert.org wrote:
> here's what I found during my little^Wextensive experiment:
> 
> 1) we have tons of duplicate segments
>      ((s1.from = s2.from) AND (s1.to = s2.to)) OR
>      ((s1.from = s2.to) AND (s1.to = s2.from))
> 2) we have 4000+ degenerate segments
>      (s.from = s.to)
> 3) we have ways with no segments
> 4) we have degenerate ways where the way is neither a proper linear 
> feature nor a proper closed polygon, but rather an unwidedly spaghetti 
> monster. most of those furthermore involve a loop of some sort...
> 
> here's what needs to be done to make the data more palatable...
> 
> * we need proper integrity checks in the database.
> * the API needs to refuse all these things with
>      406 Not Acceptable
> or
>      412 Precondition Failed

412 I think. This is planned.

> * we need higher level ways, to group all linear ways that belong to a 
> particular street

I'm not entirely sure why... I'm imagining a routing algorithim that
will notice that its on a way with the same name as the one it was just
driving on and that's it. Are there any use cases for super ways?

have fun,

SteveC steve at asklater.com http://www.asklater.com/steve/