[OSM-dev] unmodified objects being uploaded?

Richard Fairhurst richard at systemeD.net
Sat Sep 29 00:23:34 BST 2007

Jon Burgess wrote:

> Looking at the history for some objects show that they have been
> uploaded multiple times even tough there are no obvious changes:
> [...]
> There are other examples in the planet diff where only the  
> timestamp has
> been changed on an object. This could be a sign of a bug in one of the
> editors.

Potlatch will upload a new way whenever a constituent part of that  
way changes.

So, if you move the lat/long of a node within a way, then Potlatch  
will write a new revision of the way to the database, as well as a  
new revision of the node.

This isn't _quite_ as daft as it sounds. Potlatch only writes  
"created_by" tags on ways: not nodes, not segments. In the above  
example, you could tell that the edit was made by Potlatch because  
the node change (no "created_by") has the same timestamp and user id  
as a way change ("created_by=Potlatch").

(From a Potlatch, rather than OSM db, point of view, it makes a lot  
of sense: Potlatch's principal objects are ways and POIs; you can't  
edit a node in Potlatch unless it's part of one or the other.)

Is this a valid way of doing things? You could argue either way. It  
means extra way revisions are written, but it saves significant space  
by not adding created_by tags for the 350 nodes in a given way.


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