Purging the postgresql package _and_ all the installed dependencies helped. After that reinstallation created the directory /etc/postgresql/
> aptitude purge postgresql libpq5 libreadline5 postgresql-8.4 postgresql-client-8.4 postgresql-client-common postgresql-common > aptitude install postgresql
Purging the postgresql package _and_ all the installed dependencies helped. After that reinstallation created the directory /etc/postgresql/
> aptitude purge postgresql libpq5 libreadline5 postgresql-8.4 postgresql- client- 8.4 postgresql- client- common postgresql-common
> aptitude install postgresql