As of some recent version of Postgres, plpgsql is created for new
databases by default, but the sql schema export
(config.active_record.schema_format = :sql) expots a create command in
development_structure.sql, resulting in an error.
CREATE PROCEDURAL LANGUAGE plpgsql;
I could not find the version this changed in, however it is noted
I believe this is a bug at least in Rails 2.3.5?
My solution was to switch off the sql schema format in environment.rb,
which I don't believe I needed.