Here is an abstract from the pgAdmin III documentation detailing steps
to get pgAgent up and running:

pgAgent stores its configuration in the "postgres" database in your
cluster.  This database exists by default in PostgreSQL 8.1 versions;
for earlier versions you need to create the database yourself.  The
database must have the PL/pgSQL procedural language installed --
PostgreSQL's 'createlang' program can do this if required. 

On Debian you can create the postgres database like this:

    Connect as the 'postgres' operating system user and execute the
    following commands in a shell:

    postgres@anaconda:~$ createdb postgres
    postgres@anaconda:~$ createlang plpgsql postgres

Once created, connect to the new database and load the
/usr/share/pgadmin3/pgagent.sql file to the database.  You can do this
with psql if you don't have pgAdmin III installed:

    postgres@anaconda:~$ psql postgres

    Launch the following command at the psql prompt:

    \i /usr/share/pgadmin3/pgagent.sql

For more information, install pgadmin3 package and take a look at the
pgAdmin III online documentation.

 -- Raphael Enrici <blacknoz@club-internet.fr>  Fri, 14 Jul 2006 14:51:09 +0000