From OpenStreetMap Wiki
Notes on using OSM data in GIS applications, using a postGIS back end.
OSM "simple" schema
Problems with "Relations"
GIS users will typically need only a subset of the map data features at any one time,
Can/should OSM 'relations' be used to represent multilinestrings?
- Find polygons identified from 'relations' table set
- If constructed from multiple ways, i.e. not truly a closed line, then
- We probably need to copy them to a new layer and then join them.