grass-pg(1)

📦
version 8.4.2 · 10 versions
, in fedora 44

💖 grass-pg — PostgreSQL DATABASE DRIVER 💖

okay bestie, gather round, because this one is literally the moment GRASS GIS links arms with PostgreSQL and stores all your vector attributes on a whole actual database server. this is grass-pg(1) from the GRASS GIS User's Manual and it's giving main character energy fr fr 🦋

✨ PostgreSQL DATABASE DRIVER ✨

PostgreSQL database driver = the thing that lets GRASS keep your vector attributes inside a PostgreSQL server instead of just chillin' in a local file. iconic behavior, no cap. 👑

🌸 Creating a PostgreSQL database 🌸

a brand new database gets born via createdb. that's it, that's the vibe — go peek at the PostgreSQL manual if you want the deets, because it's all theirs. 💅

🎀 Connecting GRASS to PostgreSQL 🎀

here's the glow-up sequence, watch closely:

# 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

that's connect → login → vibe check the connection → vibe check the tables. we love a little pipeline. ✨

🔐 Username and password 🔐

straight from the PostgreSQL manual, bestie, quoting it so you don't have to go hunting:

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

put that line in a file, protect it, and your password never has to show up in your shell history again. we stan a discreet queen. 🤫💖

🧚 Supported SQL commands 🧚

All SQL commands that PostgreSQL supports. all of them. the whole menu. 😌

⚠️ but bestie, listen: it is not possible to use C-like escapes (the backslash ones like \n etc) inside the SQL syntax. so don't try it, she will not eat. 💀

🌈 Operators available in conditions 🌈

All SQL operators that PostgreSQL supports. yes queen, every single one. 👑

🍓 Adding an unique ID column 🍓

import vector modules need an unique ID column, and you can manifest one in a PostgreSQL table like this:

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"

add the column, spin up a sequence, fill it in, then yeet the sequence. clean. ✨

💜 Attribute import into PostgreSQL 💜

CSV import into PostgreSQL goes a little something like:

\h copy
COPY t1 FROM ’filename’ USING DELIMITERS ’,’;

(\h copy is you asking for help on copy, because we always ask for help. growth mindset. 🌱)

🦋 Geometry import from PostgreSQL table into GRASS 🦋

v.in.db creates a new vector (points) map from a database table that's holding coordinates. see here for examples. 📍

🌸 PostGIS: PostgreSQL with vector geometry 🌸

PostGIS — it adds geographic object support to PostgreSQL. it's PostgreSQL but with ✨spatial feelings✨.

🗺️ 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);

then GRASS can import this PostGIS polygon map like so:

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

import it, select from it, get the info on it. the full circle moment. 🫶

🔄 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: Saturday Jan 17 05:40:32 2026

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

and that's the whole page bestie, you ate that 💅✨

© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual — and yes this manual is literally labeled GRASS 8.4.2 at the bottom, grass-pg(1), periodt. 💖🎀🦋🌸👑

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