Many thanks for putting some numbers on this. Warin's comment would suggest it may also be more than just buildings that are involved.
For buildings the total number as a percentage is small unfortunately they tend to cluster so are more of a problem than if they were more spread out. John On Sat, Mar 11, 2023, 07:40 Frederik Ramm <frede...@remote.org> wrote: > Hi, > > I think an automatic fix of the problem is possible, however it would be > a good idea to try and find out what the root cause of the problem is - > bad software, bad imports, bad instructions? > > To get an idea of how big the issue is, I did this on a standard > rendering database: > > create table buildings as (select way,osm_id from planet_osm_polygon > where building is not null) > > select a.osm_id, b.osm_id into duplicates from buildings a, buildings b > where a.osm_id < b.osm_id and a.way ~= b.way and st_equals(a.way,b.way); > > This took a few days - probably it could have been done more efficiently > - and resulted in a list of about 70k buldings world-wide that are exact > duplicates (geoetry-wise) of other buildings. The list is here: > > http://www.remote.org/frederik/tmp/duplicatebuildings.csv > > Some buildings are in OSM three or four times (contained i nthe above in > the form of "a is duplicate of b, b is duplicate of c") but I've > extracted them in extra files: > http://www.remote.org/frederik/tmp/triplcatebuildings.csv and > http://www.remote.org/frederik/tmp/quadruplicatebuildings.csv) > > I don't have the time to analyse the situation in more detail at present > so if anyone wants to take the above lists as a basis for deeper > analysis... > > Cheers > Frederik > > -- > Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk >
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