How to create a new database with the hstore extension already installed?

Question

Recently I went into trouble trying to use hstore with Django. I installed hstore this way:

$ sudo -u postgres psql postgres=# CREATE EXTENSION hstore; WARNING:  => is deprecated as an operator name DETAIL:  This name may be disallowed altogether in future versions of PostgreSQL. CREATE EXTENSION postgres=# \dx                            List of installed extensions   Name   | Version |   Schema   |                   Description                     ---------+---------+------------+--------------------------------------------------  hstore  | 1.0     | public     | data type for storing sets of (key, value) pairs  plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language (2 rows) 

And naively thought that my new databases would include hstore. That ain't the case:

$ createdb dbtest $ psql -d dbtest -c '\dx'                  List of installed extensions   Name   | Version |   Schema   |         Description           ---------+---------+------------+------------------------------  plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language (1 row) 

Is there a way to automatically have hstore in a newly created database ?

Answer 1

Long story short:

Install hstore in the template1 database:

psql -d template1 -c 'create extension hstore;' 

---

Step-by-step explanation:

As stated by the PostgreSQL documentation:

CREATE EXTENSION loads a new extension into the current database.

Installing an extension is database-specific. The following returns you the current database name:

$ psql -c 'select current_database()'  current_database  ------------------  username (1 row) 

In case you have a database named after your username. Now with dbtest:

$ psql -d dbtest -c 'select current_database()'  current_database  ------------------  dbtest (1 row) 

Ok, you got it. Now, to create new databases with hstore installed, you'll have to install it in the template1 database. According to the doc:

CREATE DATABASE actually works by copying an existing database. By default, it copies the standard system database named template1.

Let's do this:

$ psql -d template1 -c 'create extension hstore;' 

And check that it works :

$ createdb dbtest $ psql -d dbtest -c '\dx'                  List of installed extensions   Name   | Version |   Schema   |                   Description                     ---------+---------+------------+--------------------------------------------------  hstore  | 1.0     | public     | data type for storing sets of (key, value) pairs  plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language (2 rows) 

Done!