[Talk-us] MassGIS building conversion

[Frederik Ramm]

Hi,

On 12/11/2012 01:04 AM, Paul Norman wrote:
> Lots of people include IDs because they think they might be useful but very
> seldom are they actually used.

I can second that. I have witnessed many imports painstakingly 
preserving the ID (because, after all, most of us are IT people and our 
brains are hard-wired to think that ID numbers *must* be useful - you 
know, you can cross reference things and stuff with IDs!) but I've yet 
to see anyone doing something useful with them.

I have never seen anyone who actually imported IDs and had a plan when 
asked - inevitably, the answer was "it might be useful someday, I don't 
know".

Now one of the things we say we want to do is offer data for "unexpected 
uses" so it may sound short-sighted to throw out an ID just because you 
cannot envisage a good use for it at this point in time.

On the other hand, preserving an ID in the database might send the wrong 
signal to mappers. Are they "allowed" to change something that has an 
official GIS ID? What if they split or merge objects that carry such an 
ID? Will their changes be overwritten later if they don't remove the ID? 
Etc.

My suggestion would be to not import the ID, but create a correspondence 
table during import ("imported object with ID #1234 as way #2345"). 
Since any import has to be properly documented anyway, the list can be 
stored with the other logs/documentation. If one should really want to 
follow up on this later, one can check if the objects still exist and 
haven't been modified, and then update/amend them or do whatever other 
useful thing the ID enables one to do, without polluting the database or 
puzzling mappers.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"