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PostgreSQL database driver enables GRASS to store vector attributes in PostgreSQL server.

Creating a PostgreSQL database

A new database is created with createdb, see the PostgreSQL manual for details.

Connecting GRASS to PostgreSQL

# example for connecting to a PostgreSQL server:
db.connect driver=pg database=mydb
db.login user=myname password=secret  # port=5432
db.connect -p
db.tables -p

Username and password

From the PostgresQL manual:

The file .pgpass in a user’s home directory can contain passwords to be used if the connection requires a password (and no password has been specified otherwise). On Microsoft Windows the file is named %APPDATA%\postgresql\pgpass.conf (where %APPDATA% refers to the Application Data subdirectory in the user’s profile). Alternatively, a password file can be specified using the connection parameter passfile or the environment variable PGPASSFILE. This file should contain lines of the following format:


Supported SQL commands

All SQL commands supported by PostgreSQL. It’s not possible to use C-like escapes (with backslash like \n etc) within the SQL syntax.

Operators available in conditions

All SQL operators supported by PostgreSQL.

Adding an unique ID column

Import vector module require an unique ID column which can be generated as follows in a PostgreSQL table:

db.execute sql="ALTER TABLE mytable ADD ID integer"
db.execute sql="CREATE SEQUENCE mytable_seq"
db.execute sql="UPDATE mytable SET ID = nextval(’mytable_seq’)"
db.execute sql="DROP SEQUENCE mytable_seq"

Attribute import into PostgreSQL

CSV import into PostgreSQL:

\h copy

Geometry import from PostgreSQL table into GRASS creates a new vector (points) map from a database table containing coordinates. See here for examples.

PostGIS: PostgreSQL with vector geometry

PostGIS: adds geographic object support to PostgreSQL.

Example: Import from PostGIS

In an existing PostGIS database, create the following table:

 id serial NOT NULL,
 mytime timestamp DEFAULT now(),
 text varchar,
 wkb_geometry geometry,
# insert value
INSERT INTO test (text, wkb_geometry)
 VALUES (’Name’,geometryFromText(’POLYGON((600000 200000,650000
 200000,650000 250000,600000 250000,600000 200000))’,-1));
# register geometry column
select AddGeometryColumn (’postgis’, ’test’, ’geometry’, -1, ’GEOMETRY’, 2);

GRASS can import this PostGIS polygon map as follows: input="PG:host=localhost dbname=postgis user=neteler" layer=test \
         output=test type=boundary,centroid test -t test

Geometry Converters

  • PostGIS with shp2pgsql:
    shp2pgsql -D lakespy2 lakespy2 test > lakespy2.sql
  • e00pg: E00 to PostGIS filter, see also
  • GDAL/OGR ogrinfo and ogr2ogr: GIS vector format converter and library, e.g. ArcInfo or SHAPE to PostGIS.
    ogr2ogr -f "PostgreSQL" shapefile ??

See Also

db.connect, db.execute

Database management in GRASS GIS
Help pages for database modules
SQL support in GRASS GIS


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