GRASS 5.7 tutorial introduction
Per default all GRASS 5.7 vectors are stored in native 5.7 format within the directory $GISDBASE/$LOCATION_NAME/$MAPSET/vector/$MAP/. All map related data such as geometry data, spatial index, DB-connection (dbln file) info etc. are stored in this directory. Geometry can be also read from SHAPE or other files directly (see v.external), read from PostGIS and in future maybe also write support for virtual vector maps will be implemented. See Geometry management below for details.
Default settings for vector attributes
Per default all GRASS 5.7 vector attributes are stored in a DBF table within the directory $GISDBASE/$LOCATION_NAME/$MAPSET/dbf. The default settings for attribute storage can be modified with 'v.database'. If required, a map can be linked to a certain table with 'v.db.connect'. See Attribute management below for details.
Default settings for db.* modules
The db.* set of modules can be used for simple SQL tasks in database tables. Connection must be established with 'db.connect' first. See Attribute management below for details.
|Native (default)||OGR supported formats (SHAPE, MapInfo, PostGIs etc)||DBF (default)||mySQL||PostgreSQL||ODBC|
|Geometry||2D/3D vectors, topology, Def. / Ex.||2D/3D vectors, pseudotopology, Def. / Ex.1 / Ex.2||needs PostgreSQL , pseudotopology , Def. / Ex.||not yet implemented||--||--||with PostGIS, see there||--|
|Attributes||reads/writes DBF tables, see there||with DBF, see there||with PostgreSQL, see there||not yet implemented||Int, Double, String, DateTime (?), Def. / Ex.||Int, Double, String, DateTime (?), Def.||Int, Double, String, DateTime (?), Def. / Ex.||links to various RDBMS , Def.|
|Legend:||Def.: Definition, Ex.: Example, --: not applicable|
|Remarks:|| PostGIS support: Geometry primitives (points, lines, boundaries, centroids) are stored in PostGIS and topology is build in GRASS. This is implemented for reading, but not yet for writing. PostGIS data are OGC Simple Features compliant while GRASS uses topology. These models are converted accordingly by OGR.|