[OSM-dev] Fwd: Osmosis - Cutting out a bounding box from a diff file (.osc)

[Stéphane Henriod]

On Wed, Sep 5, 2012 at 3:42 PM, sly (sylvain letuffe) <liste at letuffe.org>wrote:

> > I will end up
> > with the full planet (as every single node in OSM might be modified one
> day
> > or the other...)
>
> Well, My guess is that it will take a loooong time, so long before that you
> might need to re-import your extract for whatever fail delete, style
> change,
> software update, and so on. Thus returning your database storage back to
> your
> extract's size only.
>

200% agree! But my server quota will be reached much earlier :-) I'll keep
this one in mind if any other option fails!


>
> Note that a regular extract re-import is also a way to clean what is
> outside
> your zone of interest.
>

Might consider that as well but sounds a bit heavy to do it every minute /
hour


>
> > By the way, would this be a bug or a request of improvement for osm2pgsql
> > or osmosis?
>
> I think it is not possible to do it properly, a dirty hack loosing data
> from
> time to time could do but that will still require server ressources.
> As said earlier here :
> http://lists.openstreetmap.org/pipermail/dev/2012-August/025503.html
> A share zone for regional diffs exports could do, or support for the new
> augmented diffs in those tools.
> But both still have to be done.
>

I just tried another hack, but feel it's going nowhere:

   1. Export all from the database to an osm file => full.osm
   2. Download the latest diff file => changes.osc
   3. Apply changes.osc to full.osm => updated.osm
   4. Extract data in the bbox from updated.osm => updated_bbox.osm
   5. Derive the changes between full.osm and updated_bbox.osm =>
   change_bbox.osc

Then this change file (change_bbox.osc) contains all the changes, but only
in the bbox and can be applied to the DB, using osm2pgsql.

Although a bit heavy I thought it would work... But apparently, Osmosis
cannot read the PostGIS database, if using the osm2pgsql schema, right?
I've tried with --read-apidb, --read-pgsql and --read-pgsimp, and always
getting errors.

Can someone tell me if this approach is possible?

Thanks again!

Stéphane


>
> --
> sly
> qui suis-je : http://sly.letuffe.org
> email perso : sylvain chez letuffe un point org
>
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