[OSM-talk] Historical Data in OSM database

[Lauri Kytömaa]

Martin Koppenhoefer wrote:
>I think this has to be done, and it can be done. We could invent a way
>to flag stuff that we remove because it ceased to exist as such, and

The solution that works right now, even if it is a bit laborous
sometimes: first prepend all keys with "was:" or "past:"
(for example change highway=track -> was:highway=track), add end_date if 
known and upload, then delete and upload again.

This way historical data ends up deleted, but the last version tells that 
the feature didn't exist anymore at the time it was deleted. Nothing 
supports it, but such data could then be extracted from the database or 
from the full history files, if someone really wanted to.

Mapped objects very seldom get dismantled, so the overhead for storing one 
"extra" version in historic planets and full-history is minimal. And most 
wouldn't care enough to do it for POIs, trees(!) or other constantly 
changing features - just old buildings, major roadworks and the like.

-- 
Alv