[Check_mk (english)] postgres plugin cause excessive log

I'm trying postgres plugin, but this causing excessive log in auth.log
(ubuntu server)

su[2654]: Successful su for postgres by root
Jul 13 12:30:04 su[2654]: + ??? root:postgres
Jul 13 12:30:04 su[2654]: pam_unix(su:session): session opened for user
postgres by (uid=0)
Jul 13 12:30:04 su[2654]: pam_unix(su:session): session closed for user
postgres

This for every db. It's quite annoing.. someone have a workaround for this?