[OSM-talk] Id stability

[Colin Smale]

On 02/08/2011 11:08, Frederik Ramm wrote:
> Well then let them think of a solution. Using our internal IDs to link 
> to is a vapourvare "solution" just the same. Anyone who uses them must 
> be aware that they might change at any time, even wholesale.
Exactly.

OSM does not cause buildings to be created or roads to be built or 
restaurants to be opened.

Very many real-world objects already have a stable unique identifier. 
Every time a building is constructed, a new ID is created in the list of 
all buildings maintained by some governmental organisation. Every time a 
railway station is built it gets an ID in the list maintained by the 
railway operator. Every time a company is created it gets a company 
number in some administration or other. Just add these external IDs to 
the OSM data, together with an indication of the relevant authority.

Example: Victoria Station in London is known by the unique identifier 
"VIC" in the list of stations maintained by Network Rail. So it might 
have tags "ref=VIC" and "source:ref=Network Rail". There's your stable 
ID: whenever you want to find it, query on these tags. Of course 
performance would likely be a major issue here, but that is probably not 
insurmountable and anyway should not be used as an excuse for not doing 
the Right Thing.

Colin