Multiple passwords with sql authentication

I'm currently working on a control panel which is using postfix, dovecot and other applications and I want to add application specific passwords to increase security.

I found one solution [1], however it requires the password to be included in the query which is something I do not want to do, because the query may be written in clear-text to log-files. So I'm wondering if there is a way to have multiple passwords with dovecot without risking passwords being leakied in clear-text to log-files.

[1] http://wiki2.dovecot.org/AuthDatabase/SQL#Password_verification_by_SQL_serve...