---
name: "grass-pg"
section: "1grass"
platform: "linux"
package: "grass-doc"
version: "8.4.1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/grass-pg"
---

# grass-pg(1grass)

## PostgreSQL DATABASE DRIVER

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 host=myserver.osgeo.org  # 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:\

```
hostname:port:database:username:password
```

## 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
COPY t1 FROM ’filename’ USING DELIMITERS ’,’;
```

## Geometry import from PostgreSQL table into GRASS

*v.in.db* 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:\

```
CREATE TABLE test
(
 id serial NOT NULL,
 mytime timestamp DEFAULT now(),
 text varchar,
 wkb_geometry geometry,
 CONSTRAINT test_pkey PRIMARY KEY (id)
) WITHOUT OIDS;
# 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:\

```
v.in.ogr input="PG:host=localhost dbname=postgis user=neteler" layer=test \
         output=test type=boundary,centroid
v.db.select test
v.info -t test
```

### Geometry Converters

- •

  PostGIS with shp2pgsql:\
   `shp2pgsql -D lakespy2 lakespy2 test > lakespy2.sql`

- •

  e00pg: E00 to PostGIS filter, see also *v.in.e00*.

- •

  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\

## REFERENCES

- •

  PostgreSQL web site

- •

  pgAdmin graphical user interface

- •

  GDAL/OGR PostgreSQL driver documentation

## SOURCE CODE

Available at: PostgreSQL DATABASE DRIVER source code (history)

Accessed: Monday Feb 24 17:50:20 2025

Main index \| Topics index \| Keywords index \| Graphical index \| Full index

© 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual