[OSM-dev] SoC project idea: Wikifikation of OSM

Karl Newman siliconfiend at gmail.com
Mon Mar 31 15:10:38 BST 2008

On Mon, Mar 31, 2008 at 8:55 AM, Steve Hill <steve at nexusuk.org> wrote:

> On Sun, 30 Mar 2008, jn at jonemo.de wrote:
> > I came up with loads of great ideas just to realise that Frederik Ramm
> has
> > written pretty much the same on the wiki page ?Changesets and Reverts?.
> I've thought for a long time that OSM needs a Subversion-style global
> revision number and atomic commits.  So, for example, if someone commits
> completely broken data you can roll back that revision in its entireity.
> Also, being able to find out what has changed within a specified bounding
> box since a given date would be really useful - it would allow people to
> take responsibility for an area and be easilly able to check and correct
> changes made within that area.
>  - Steve

Well, that sounds like a nice idea, but it's fraught with peril. You
wouldn't be able to arbitrarily select any given changeset/commit for
reversion because of edits that may have happened after that commit. For
example, if someone deleted a bunch of relations, then later someone else
deleted a way that was a member of one of the relations, you couldn't simply
un-delete the relations because then you'd have a referential integrity
problem. Or a more subtle example--someone deletes a way which shares a node
with another way. Then the (formerly) shared node is moved. If you un-delete
the first way, is it the same as before the delete? From the perspective of
the database way table, it is (the node list is the same), but on the map it
may be drastically different.

It may be possible to accomplish roll-back such as you're describing, but it
will need to be handled very carefully.

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