Rule for don't log specific user session.

Hello, Is there a way to don't log nothing for a specific user, creating a rule in sql_log? You will probably ask me why! Because i have a plugin running on nagios, that checks for authentication with a specific user ex: "testuser" every 5 minutes, and at the end of the day my database grows with useless information. We are a global hotspot provider, so this check running on nagios is performed in 10.000 hotspots, to test for authentication, so you could imagine that this "testuser" generates infinite registers. I think put some kind of trigger to do that, will probably slow down my server performance, because we have a huge users database. I'm running freeradius(1.1.7) + postgre. Regards, Rafael Medici