I was under the impression that recent modern databases, like PG, allow you to transfer control to an out-of-system (system being the DB engine) module (shared lib, dll). That is while triggers transfer control within the system, now mechanisms exists that allow you to go outside of the system. In that context, whence the control is transferred to a C, Perl or whatever language, who is to stop that function from doing anything it wants.
I appreciate a clarification.
Medi