PostgreSQL, Second Edition

Securing Functions

When you call a function (or execute a trigger), that function typically operates with the privileges granted to your user ID or group. That means, for example, that a function can't UPDATE values in a given table unless you hold UPDATE privileges for that table. That's usually a good thing—you don't want a user to suddenly gain extra privileges just by calling a function. But it can also be inconvenient.

Say you're storing bookkeeping information in a PostgreSQL database and you've created a number of stored procedures (functions) to manage that data. You're running a large company with its own accounting department and you've created a group named CLERKS that holds limited privileges. In particular, a CLERK can SELECT values ...