> On Aug 7, 2018, at 11:42, Ken Tanzer <ken.tan...@gmail.com> wrote: > I assume that's "for all users and all sessions," but either in theory or in > practice is there a limit to how long a stale value might persist? And, if > you were to drop and recreate a function with the same name & parameters, > would it start fresh at that point? And is there a way to flush any caching? > (It's surely best to just declare Stable, but I'm wondering about cases that > might have _very_ infrequently-changed values.)
Well, the extreme case is an IMMUTABLE function used to create an expression index; then, the value lasts as long as the index does. The best way to think of an IMMUTABLE is that it is a pure function, unchanged by system state. (This is one of the reasons that datetime-related functions are often STABLE rather than IMMUTABLE, due to time zone changes.) -- -- Christophe Pettus x...@thebuild.com
