[OSM-dev] (Partially) duplicate ways

[Gary68]

http://wiki.openstreetmap.org/wiki/Waydupes.pl


On Fri, 2009-08-14 at 17:23 +0200, Joachim Zobel wrote:
> Hi.
> 
> I have searched for ways that are contained in other ways (see attached
> SQL) and found 10000+ (5000+ of length > 2) in my local database
> containing a post 0.6-migration map (from 2009-04) of germany. It seems
> there are quite a lot of obvious inconsistencies like e.g. the ways
> 33816455, 33816484, 33817385, 33817396 or the ways  33309970, 33309994,
> 33310274, 33310413 or 33598434, 33598740.
> 
> The latest example (ways 33857470, 33857473) is from 2009-04-30. It
> looks like this is not a pre-0.6 problem.
> 
> I did find the first example because they behave weird when split with
> JOSM, so they are obviously harmful. 
> 
> Is anybody else currently working on this topic? 
> 
> Sincerely,
> Joachim
> 
>         -- Find ways contained in other ways
>         -- Attention: takes hours, even on a map of germany
>     SELECT wnl.id, wnr.id, COUNT(1) AS cnt
>       FROM current_way_nodes wnl
>       JOIN current_way_nodes wnr
>         ON wnl.node_id = wnr.node_id 
>        AND wnl.id < wnr.id
>   GROUP BY wnl.id, wnr.id
>     HAVING COUNT(DISTINCT (wnr.sequence_id - wnl.sequence_id)) = 1
>        AND COUNT(1) IN (SELECT COUNT(1)
>                           FROM current_way_nodes
>                          WHERE id IN (wnl.id, wnr.id)
>                       GROUP BY id)
>     -- AND COUNT(1) > 2
> 
> 
> 
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