Change Details

{T155924}, {T154599}, and {T155923} are all aspects of how to handle relations other than `type=multipolygon`, `type=route`, and `type=boundary` with way members. Rather than trying to figure out exactly which issue to comment on, I'm merging them all in here. I don't know if the wikidata tagging in OSM in those issues is correct, but the basic issue is creating a geometry from an arbitrary relation. In the issues referenced, they were waterway relations, boundary relations containing relations, and public transport route masters. multipolgon, route, and boundary relations have well-established ways of creating geometries from them and are handled by osm2pgsql. Some of the relation types above like waterway relations **could** be handled by osm2pgsql but are not with the default data transformation. Others, like public_transport and relations of relations cannot be handled by osm2pgsql, and may not even have a sensible representation as a single geometry with tags. This means if we decide we want to handle arbitrary relations, we would need to deploy another database specific for geoline/geoshape and abandon the possibility of returning OSM tags for some objects. We could then build a GeometryCollection for all relations, which could be used to draw something on a map, but not always a good interpretation. For example an area with a hole drawn as a MP when interpreted this way is a closed line inside a closed line.

2021 update: Wikimedia has switched from osm2pgsql to imposm3, support for more relation types can be configured, now `type=waterway` is supported in addition to previous three types. It should be further reviewed which other relation types can be and should be supported. --- {T155924}, {T154599}, and {T155923} are all aspects of how to handle relations other than `type=multipolygon`, `type=route`, and `type=boundary` with way members. Rather than trying to figure out exactly which issue to comment on, I'm merging them all in here. I don't know if the wikidata tagging in OSM in those issues is correct, but the basic issue is creating a geometry from an arbitrary relation. In the issues referenced, they were waterway relations, boundary relations containing relations, and public transport route masters. multipolgon, route, and boundary relations have well-established ways of creating geometries from them and are handled by osm2pgsql. Some of the relation types above like waterway relations **could** be handled by osm2pgsql but are not with the default data transformation. Others, like public_transport and relations of relations cannot be handled by osm2pgsql, and may not even have a sensible representation as a single geometry with tags. This means if we decide we want to handle arbitrary relations, we would need to deploy another database specific for geoline/geoshape and abandon the possibility of returning OSM tags for some objects. We could then build a GeometryCollection for all relations, which could be used to draw something on a map, but not always a good interpretation. For example an area with a hole drawn as a MP when interpreted this way is a closed line inside a closed line.

2021 update: Wikimedia has switched from osm2pgsql to imposm3, support for more relation types can be configured, now `type=waterway` is supported in addition to previous three types. It should be further reviewed which other relation types can be and should be supported. --- {T155924}, {T154599}, and {T155923} are all aspects of how to handle relations other than `type=multipolygon`, `type=route`, and `type=boundary` with way members. Rather than trying to figure out exactly which issue to comment on, I'm merging them all in here. I don't know if the wikidata tagging in OSM in those issues is correct, but the basic issue is creating a geometry from an arbitrary relation. In the issues referenced, they were waterway relations, boundary relations containing relations, and public transport route masters. multipolgon, route, and boundary relations have well-established ways of creating geometries from them and are handled by osm2pgsql. Some of the relation types above like waterway relations **could** be handled by osm2pgsql but are not with the default data transformation. Others, like public_transport and relations of relations cannot be handled by osm2pgsql, and may not even have a sensible representation as a single geometry with tags. This means if we decide we want to handle arbitrary relations, we would need to deploy another database specific for geoline/geoshape and abandon the possibility of returning OSM tags for some objects. We could then build a GeometryCollection for all relations, which could be used to draw something on a map, but not always a good interpretation. For example an area with a hole drawn as a MP when interpreted this way is a closed line inside a closed line.