[OSM-talk] Id stability

[andrzej zaborowski]

On 1 August 2011 09:52, Maarten Deen <mdeen en xs4all.nl> wrote:
> On Mon, 01 Aug 2011 09:21:44 +0200, Frederik Ramm wrote:
>
>> (Two or three people have also started tagging OSM objects with UUID
>> tags but I don't think that that's anything more than database bloat.
>> I think that about 99.9% of UUID tags in the database come from a
>> building import where somebody automatically assigned an UUID to every
>> last garden shed. Not useful.)
>
> Even though, it might be the best solution. The other solution would be that
> everybody who wants to use the object for their purpose adds their own
> home-made tag to it. And that certainly would be a database bloat.

Just throwing some ideas here, but one might consider using the OSM ID
+ version as the unique id.  If the object is later changed in OSM,
deleted and recreated, or whatever, it can be tagged with
object_id=5764736:v1 to mean that it is still the same object as had
been referenced by 5764736:v1 from elsewhere.

Or create an OSM relation containing just the thing you want to link
to and reference the relation's Id.... the editors already support
warning when somethign bad happens to a relation member.  Relations
are unlikely to be reused for a compeltely new purpose and they can be
undeleted and modified to match changes in reality.  Using relations
also allows an osm entity to be part of multiple "real world" objects,
or multiple osm entities to form one "real world" object, both of
which may be desired.

>
> Of course you would add a UUID tag only to objects that are actualy
> referenced. And then you would need some way to enforce uniqueness.

Because of the above I'm not sure if you want to enforce uniqueness,
you might even want >1 UUIDs per osm entity.
Cheers