Hi
I wonder why osm_id and tags don't match in
planet_polygon:
osm_mapnik=> SELECT osm_id, name, tags->'wikipedia' AS wikipedia FROM
planet_polygon WHERE osm_id=-1685716;
osm_id | name | wikipedia
----------+-------+-----------
-1685716 | Utøya | Utøya
(1 row)
As if these name and wikipedia tags belong to relation 1685716.
Whereas they are actually properities of way 4171584
(
http://www.openstreetmap.org/browse/relation/1685716,
http://www.openstreetmap.org/browse/way/4171584)
Because you're querying a rendering-database which is preprocessed in order to prduce
good rendering results ans -times. One of te preprocessing steps taken is, in the
polygon-build phase, "if the relation does not have any interesting tags, copy them
from the outer way". This may be wrong or right in the sense of how Relations are
defined (there are different definitions for that, btw.), but it's just how our
impiorter handles it.
Refer to
http://wiki.openstreetmap.org/wiki/Relation:multipolygon#Tagging for one of the
definitions.
Peter