Debian will not remove configuration files if you don't purge
the packages. If you need to reconfigure dotlrn:
dpkg-reconfigure dotlrn
Too, dotlrn suggests the postgresql package but it doesn't enforce it as a dependency so you can have a different box running the postgres server.
A simple setup with dotlrn and postgres in the same box:
apt-get install dotlrn postgresql
When asked in the dotlrn package setup, the defaults will make it work with a local postgresql server.
