PostGIS
Help pages
- grass-pg help page
- grass-odbc help page
Link to external dataset
Import into GRASS
There is a fundamental difference between the PostGIS format which is non-topological and the internal GRASS format which is topological and which, thus, does not really allow for overlapping polygons. You can digitize them, but they are not really useful...
You cannot directly process a PostGIS table in GRASS. GRASS has its own internal vector format.
You can link a GRASS layer to a PostgreSQL table, though. v.db.connect (??)