arch-wiki-md-repo/wiki/_content/english/PostGIS.md

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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](/index.php/PostgreSQL "PostgreSQL") page.

## Contents

*   [1 Installing PostGIS](#Installing_PostGIS)
*   [2 Installing PostGIS Extension](#Installing_PostGIS_Extension)
*   [3 Creating a Template PostGIS Database](#Creating_a_Template_PostGIS_Database)
*   [4 Creating a PostGIS Database From the Template](#Creating_a_PostGIS_Database_From_the_Template)
*   [5 More Resources](#More_Resources)
*   [6 PostGIS failing with json_tokener_error](#PostGIS_failing_with_json_tokener_error)

## Installing PostGIS

[Install](/index.php/Install "Install") the [postgis](https://www.archlinux.org/packages/?name=postgis) package.

## Installing PostGIS Extension

Since [[PostgreSQL 9.1][[1]](http://postgis.net/docs/postgis_installation.html#make_install_postgis_extensions)], 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](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](http://postgis.net/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](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.