I want to create a table with a geometry field in it. e.g.:
CREATE TABLE ptgeogwgs(gid serial PRIMARY KEY, geog geography(POINT) );
In my case, this geometry field can either be a POINT, a LINESTRING or a POLYGON. I couldn't find any examples where that unique column could take three different types. So I guess the type of geometry should be fixed in advance. Nonetheless, is is better to create one table for each geometry type or create multiple columns, one for each geometry type.
Furthermore, if I choose for the second option, are the two empty geometry fields stored as "null" and therefore taking some memory space or doesn't empty fields in PostGIS table take any space?