I am currently working in map for a province of Papua New Guinea. In OpenStreetMap (OSM) I have recently updated and added new relations for boundaries of admin_level=5 and admin_level=6, which were not present before.
The relations I am analysing are the following:
5,259,919. You can check them here:
I extract the OSM data with
http://extract.bbbike.org in PBF format, and then I export it with ogr2ogr using a command similar to the following
ogr2ogr -f "SQLite" -dsco SPATIALITE=YES png-full-test.db planet_xxx.osm.pbf
The resulting .db is later used in QGIS for creating the map. I use a custom osmconf.ini to extract the tags I need for my map.
The relations were created using both non-existing lines (borders where there is no other feature, created just for this purpose) and existing lines (such as rivers, which are part of the relation). The latter do not have specific tags for boundary=administrative or admin_level=6 as these are included in the relation (and according to my best understanding, there is no need to put them twice).
However, when I open the resulting file, only the lines which have the tags explicitly added will be shown. The ones such as rivers or roads, which are part of the relations but that they don't have neither boundary or admin_level tag, will not be listed in none of the resulting tables (other_relations, lines, points, multilinestrings or multipolygons). They are lost in the process. A quick and dirty solution would be to add the missing tags to the rivers / roads, but I am wondering if there is any other cleaner way to solve the issue.