[OSM-dev] Tiling the Planet and Missing Nodes

[Thomas Wood]

2009/3/28 Ben Supnik <bsupnik at xsquawkbox.net>:
> But...it appears that there are cases where a node has been deleted from
> the database while being referenced by a way.
>
>  From what I can tell, this is not a desired condition, but it is
> pervasive due to previous bugs in the OSM software, and there isn't a
> process to "globally fix it" (e.g. delete the way reference, not that
> that would even necessarily be the right thing to do).
>
>  From my last run, way id 4043882 references node 365476284 that is not
> present in the dump.  This is with planet version 090325.  Grep reveals
> that 365476284 is only present in an "nd" tag as part of the ref=
> statement. :-(

The issue here is not with the database, nor the API software, nor
potlatch for once(!), it is in fact a known issue with the planet
dumper.

The history of the way:
<osm version="0.5" generator="OpenStreetMap server">
...
<way id="4043882" visible="true" timestamp="2009-03-25T02:02:58+00:00"
user="hanoj">
<nd ref="21411063"/>
<nd ref="21411065"/>
<nd ref="365476284"/>
<nd ref="25262373"/>
<nd ref="21411066"/>
<nd ref="21411068"/>
<nd ref="33951479"/>
<tag k="name" v="Trýbova"/>
<tag k="created_by" v="JOSM"/>
<tag k="highway" v="residential"/>
</way>
</osm>

And the quoted node:
<osm version="0.5" generator="OpenStreetMap server">
<node id="365476284" lat="49.1954914" lon="16.5941908" user="hanoj"
visible="true" timestamp="2009-03-25T01:55:52+00:00"/>
</osm>

Carefully note the timestamps - the node was created on a Wednesday -
planet dump day. The dumper already had written the nodes out to file
before the new node had been created, but read the way from the
database after it had been modified.

I believe the recommended method to get a fully consistant dump of the
data was to download the dump, then apply the next day's changefile.

-- 
Regards,
Thomas Wood
(Edgemaster)