[OSM-dev] question about node identifiers

[Frank O'Dwyer]

John Smith wrote:
> If you parse change sets, you would get the node id to be deleted 
> along with a new node id if there was something added, otherwise if 
> it's just modified you get a modified change along with the original id.
But would still have to pair them up myself, right?  I would parse out a 
set of deleted nodes and a set of added nodes and would need to figure 
out that (delete x) and (add y) referrred to the same logical POI - e.g. 
because they had the same / similar name and properties and near each 
other? Or are they already paired up in the change set?

Also when tracking changesets, is the maximum period daily or is it 
possible to get them on a weekly / monthly cycle? Or to put it another 
way, I'm currently experimenting with a snapshot of planet.osm I grabbed 
a few days ago. How often do I need to grab changesets to stay current? 
Say if I want to get a single changeset to cover a period of a month, is 
that possible, or do I need to be mirroring changesets every day?

I also only want to get POI nodes and not ways/relations etc, so I don't 
really need the whole planet.osm, just a subset - is there a recommended 
way to ask for only those to save bandwidth and load on the server? It 
would also save me time on parsing as currently parsing out the amenity 
nodes takes ages.

Last thing I am wondering is if there is a description somewhere of the 
mandatory / optional tags per different type of amenity? I assume this 
changes over time and so if I'm parsing these I need to handle cases 
where a particular expected tag is not there.

Cheers,
Frank