New answers tagged sqlite
This probably won't work in practice, but it does in theory: ST_DumpRings to get all the linework from your polygons ST_Union the rings to get a single set of boundaries ST_Polygonize the linework to get a complete set of areas bounded by the linework ST_PointOnSurface the areas to get points ST_Intersects the points with the original polygons and Count(*) ...
National Earth SQLite database uses Well-known binary format in GEOMETRY column. It's well described on this Wikipedia page, however you can also find some libraries to handle it, for example http://geophp.net/ If you want to use it with SpatiaLite, here is example of SQL query: SELECT name, GeometryType(GeomFromWKB(GEOMETRY)) FROM ne_10m_admin_0_countries ...
Oh, I think I found it by myself. It's "Well-known binary format". What an irony. http://en.wikipedia.org/wiki/Well-known_text#Well-known_binary I successfully used http://geophp.net/ programming library to operate on those geometry data.
Top 50 recent answers are included