TOra, нет connection provider для Postgres

apt-get install libqt4-sql-psql

или совсем так:
apt-get install libqt4-sql-mysql libqt4-sql-psql libqt4-sql-sqlite libqt4-sql-odbc libqt4-sql-tds

для справки:
TOra is an open-source multi-platform database management GUI that supports accessing most of the common database platforms in use, including Oracle, MySQL, and Postgres, as well as limited support for any target that can be accessed through Qt's ODBC support.