[OSM-talk] Brainstorming: Simple Revert-Tools

[Andy Allan]

On Thu, Sep 3, 2009 at 10:36 AM, Peter Miller<peter.miller at itoworld.com> wrote:

> I agree that there should be a 'easy revert' for a single changeset.
> This might result in a 'clean' revert (where none of the features have
> been touched since),

Just want to point out that there's more to life in OSM than
particular features, and practically no changeset can be cleanly
reverted. Two examples:

Bad changeset #123: delete the node "London". Was node 456 v10, now
456 v11 (deleted)
(Intermediate changeset: add a node for London)
Revert changeset #123: node 456 hasn't been touched since, so reinstate.

Not what you wanted.

Bad changeset #333: moved node #1234 (v2->v3) in way #4567 (v15 - not
changed in this changeset)
(Intermediate changeset: remove node #1234 from way #4567, but the
node isn't itself deleted)
Revert changset #333:  node #1234 hasn't been touched since, move it
back to where it started.

Not what you wanted either.

The version numbers only apply to the primitives, not the state of the
system (which has both relationships between primitives and spatial
relationships). This makes hands-off reverting very tricky.

Cheers,
Andy