[OSM-talk] Orphaned Relations

Sarah Hoffmann lonvia at denofr.de
Sun Jul 17 22:55:44 BST 2011


Hi,

I recently stumbled upon some empty route relations, so I had a
closer look at the OSM planet and found that there are about 
10.000 orphaned relations in the database and the number is growing. 

With orphaned I mean relations that have no members and are not 
member of any other relation. Some are completely empty but most 
still have some tags. I have created a list of the relations sorted 
by last editing user here:

http://osm.lonvia.de/stuff/orphans.html

Quite a few of those have been created by some import gone wrong
but there is also a significant part that are the result of editing
mistakes. Some relations seem to have been uploaded empty in the
first place. In some relations, especially multipolygons, the member
ways were deleted but the relation was left in the DB. And then there 
seem to be some users that think that removing all members from a
relation is the same as deleting the relation.

According to the created_by tag, this seems to be a problem in 
all major editors:

4188 JOSM
1614 Potlach 1
1565 Potlach 2
  55 Merkaartor
	 2 Mapzen Beta
2671 (bots and scripts)

I don't know about forbitting orphaned relations but it would
certainly be helpful if the editors would show a big red warning
sign if somebody tries to upload an empty relation.

Question remains what to do with the existing orphaned relations.
Is there any legimate use for them or would it be save to simply
delete them all?

Cheers,

Sarah




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