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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

       Last changed: $Date: 2018-07-13 11:36:07 +0200 (Fri, 13 Jul 2018) $

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