[OSM-dev] unmodified objects being uploaded?

Richard Fairhurst richard at systemeD.net
Sat Sep 29 14:46:49 BST 2007

Jon Burgess wrote:

> I understand that by not adding the created_by tag we save some space.
> I still do not see what Potlatch would lose if it did not upload a new
> version of a node which has absolutely zero differences. From what you
> mention it seems the value of this is to say that the node was part  
> of a
> way which had some other modifcations made. Is there  anything else?
> This seems to mean that if a user moves a single node in a way using
> Potlatch then all nodes get changed to have his user id and results in
> unnecessary work for for the backend DB to rewrite all these  
> unmodified
> nodes.

Not quite.

If a user moves a single node in a way using Potlatch, then:

- that node is updated (i.e. new history entry made, current_nodes  
- a new revision of the way is written (to give the created_by  

Other nodes, and segments, are unaffected.

You can see the logic at http://trac.openstreetmap.org/browser/sites/ 
rails_port/app/controllers/amf_controller.rb#L280 . As you'll see  
from line 350, a node is only written if the latitude, longitude or  
tags have changed.


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