[OSM-talk] Id stability

[John F. Eldredge]

Gregor Horvath <gregor at ediwo.com> wrote:

> Hi,
> 
> Am Mon, 01 Aug 2011 09:21:44 +0200
> schrieb Frederik Ramm <frederik at remote.org>:
>  
> > That was me. There are a number of other reasons why IDs could
> > "break". One is the expansion of POI nodes into buildings that Toby
> > mentioned. Another is the splitting of ways (old ID would then point
> > to only half) or merging (old ID would become invalid in 50% of
> > cases). Same with the re-structuring of relations or the re-mapping
> > of stuff in the course of the license change.
> 
> It is a logically inaccurate to delete an ID in such cases.
> What you actually logically do is replacing an ID, or creating an
> alias.
> The problem is there is no semantic in OSM data to express such a move
> operation. Deleting is the wrong one. Deleting means a destroyed house
> or physically removed street and in this case it is logically correct
> that the ID is gone.
> 
> So my proposal is to describe move operations in OSM data.
> For example: Instead of deleting, all tags of the object or removed
> and
> a "alias_for" "joined_with" "splitted_to" tag(s) which points
> to the new correct node(s) ID is inserted to the old node .
> 
> Than external programs can find the proper one with the old id and the
> OSM data gets richer and more accurate.
> 
> --
> Greg
> 
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Preferably "split_to", rather than "splitted_to", since there is no such English word as "splitted".  Otherwise, this sounds like a good idea.  Note that there might need to be multiple instances of such a tag, with some form of version information as part of the value.  For example, a POI node might later be joined to be part of an area representing a shop; this shop area might later be joined to others to represent an entire building that contains several shops.
-- 
John F. Eldredge -- john at jfeldredge.com
"Reserve your right to think, for even to think wrongly is better than not to think at all." -- Hypatia of Alexandria