System Administrator's Guide/Enabling Plpgsql
If your database has been configured without plpgsql as a trusted language, and you are installing or upgrading to Mahara 1.5, you will need to ensure the plpgsql language is available in your Mahara database. The following commands can be used in your psql database client:
CREATE TRUSTED LANGUAGE plpgsql; GRANT USAGE ON LANGUAGE plpgsql TO <mahara_db_user>;
Replace <mahara_db_user> with the user that mahara connects to the db with.
(Tested on Red Hat Enterprise Linux 5.8, PostgreSQL 8.1.23)