PostGIS
PostGIS adds support for geographic objects in the PostgreSQL database. This document describes the process for installing PostGIS and creating a template PostGIS database. It is assumed that PostgreSQL has been installed. If it hasn't, please refer to the PostgreSQL page.
Contents
Installing PostGIS
Installing PostGIS Extension
Since [[PostgreSQL 9.1][1]], the preferred approach is to install PostGIS and enable postgis extension for each spatial database.
$ psql -- verify available extensions SELECT name, default_version,installed_version FROM pg_available_extensions WHERE name LIKE 'postgis%' ; -- install extension for spatial database mygisdb \c mygisdb CREATE EXTENSION postgis; CREATE EXTENSION postgis_topology; CREATE EXTENSION fuzzystrmatch; CREATE EXTENSION postgis_tiger_geocoder;
You don't need to do the below "Creating a Template PostGIS Database" step if you use PostGIS extension.
- upgrade postgis extension
$ psql ALTER EXTENSION postgis UPDATE TO "2.1.0";
- migrate spatial database created with postgis_template
Dump and drop the spatial database, re-create a spatial database with extension, and restore the dumped database. Follow http://www.postgis.net/docs/postgis_installation.html#hard_upgrade for specific commands.
Creating a Template PostGIS Database
- Become the postgres user.
$ su # su - postgres
- If you haven't created a superuser for accessing PostgreSQL, you may want do that now. You will be prompted for granting permissions to that user.
$ createuser [username]
- Create a new database called "template_postgis".
$ createdb -O [username] template_postgis -E UTF-8
- PostGIS requires the pl/pgSQL language to be installed on a database.
$ createlang plpgsql template_postgis
- Load the PostGIS spatial types for PostgreSQL and spatial reference systems. "postgis.sql" and "spatial_ref_sys.sql" are part of the installation of PostGIS, and may reside somewhere else besides "/usr/sharepostgresql/contrib/postgis-2.1/" depending on the installation. (Below is for default postgis 2.1 installation)
$ psql -d template_postgis -f /usr/share/postgresql/contrib/postgis-2.1/postgis.sql $ psql -d template_postgis -f /usr/share/postgresql/contrib/postgis-2.1/spatial_ref_sys.sql
- Make it a real template.
$ psql UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template_postgis';
Creating a PostGIS Database From the Template
- It's common practice to reserve a bare template for creating new PostGIS databases. As a PostgreSQL superuser, the following command will create a new database:
$ createdb -T template_postgis [new_postgis_db]
More Resources
For additional resources concerning PostGIS, check out the PostGIS Documentation.
PostGIS failing with json_tokener_error
This happends when adding postgis as an extension. The libjson-c package has changed, and PostGIS hasn't put out a stable release with this yet. Its in 2.1.0rc1, though. The bug-report is http://trac.osgeo.org/postgis/ticket/2213
The fix is to download the postgis PKGBUILD and then change the version to '2.1.0rc1'. Don't forget to change the sha256sum.