Just how buggy these packages really are is discussed in #595652 at the moment.
The commandline to find these logs is:
COMMAND='grep -E "(warning: database package not installed|dbconfig-common: .* configure: (aborted|noninteractive fail|ignoring errors from here forwards)|updating database schema for .*...command failed with code 0|(postgres|psql): could not connect to server: No such file or directory|DBI connect.* failed: could not connect to server|pg_pconnect\(\): Unable to connect to PostgreSQL server|Non-default port in /etc/postgresql/.*/main/postgresql.conf|Unable to connect to MySQL server|unable to connect to mysql server)"'