[OSM-dev] Wrong node ids in osmupdated planet

[Jochen Topf]

On Wed, Oct 11, 2017 at 10:56:26AM +0300, Ilya Zverev wrote:
> I have downloaded a planet file around... March?.. and have been updating it using osmupdate 0.3H every two weeks or so. And now I've met a curious bug. Look at these way nodes:
> 
> $ ./osmconvert planet-171009.o5m --out-osm | grep -A 3 '<way.*419952872'
> 	<way id="419952872" version="2" timestamp="2016-05-27T21:00:47Z" changeset="39613682" uid="362997" user="Virgile1994">
> 		<nd ref="4199393688"/>
> 		<nd ref="4199393273"/>
> 
> But OSM API gives: http://www.openstreetmap.org/api/0.6/way/419952872
> 
> <way id="419952872" visible="true" version="2" changeset="39613682" timestamp="2016-05-27T21:00:47Z" user="Virgile1994" uid="362997">
> <nd ref="4199393690"/>
> <nd ref="4199393275"/>
> 
> How could this happen?

This way always had those two nodes in it, even in version 1. So it
doesn't look like something went wrong because of a missed change file
or so. But note that the node IDs are both off by 2. Internally o5m uses
delta-encoding when encoding lists of nodes, so if one is off, then the
next one will be off by the same amount. So this is either a bug in
osmupdate/osmconvert or a bit flipped on you due to bad RAM or so.

Jochen
-- 
Jochen Topf  jochen at remote.org  https://www.jochentopf.com/  +49-351-31778688