[OSM-talk] caveat - potlatch overrides extern changes

Karl Eichwalder ke at gnu.franken.de
Sun Jan 18 08:39:32 GMT 2009

Do not take me wrong--since quite some time I like potlatch a lot.
Unfortunately, there is at least one feature that can destroy data

>From time to time I use josm and potlatch more or less simultaniesly.
If I upload data with josm, potlatch does not see these changes.
potlatch seems to save its data more or less unconditionally; it does
not warn the user that data changes took place externally.

0/ To reproduce, load the same way in josm and potlatch.  Try a simple
way such as:

        1         2     3

1/ Within josm, add a node (+) and move it:

                    / \
                   /   \
        o---------o     o
        1         2     3

   Upload this change.

   In potlatch this change is not visible (that's ok because it must
   not query the database all the time).

2/ In potlatch at node 2:

        1         2     3

3/ Download data from the server with josm.  It now looks as follows:


        1         2     3

potlatch's behavior isn't fair, I'd say.  It must not change existing
data siliently.  Instead, it should warn the use and download recent
data from the server.  Then you could either display a conflict or drop
the change done by the potlatch user.

There is no reason to assume that the data entered by the potlatch user
is better than the recent change done externally.

Karl Eichwalder

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