"Kevin Grittner" <kevin.gritt...@wicourts.gov> writes: > Greg Stark <st...@mit.edu> wrote: >> Only IMMUTABLE functions can be used in CHECK constraints. > It doesn't look like that to me:
No, we have never enforced that. IIRC the idea has been discussed, but we thought that adding the restriction would break too many existing applications. > A CHECK constraint using a volatile function is potentially valid > and useful, IMO. Think about a column which is supposed to record > the moment of an event which has occurred. It could make sense to > ensure that the timestamptz value is < now(); On the other hand, an > index entry based on now() is clearly a problem. This example is actually stable not volatile, but if for some reason you wanted to use clock_timestamp() then it would be volatile. Probably a more interesting question is whether it'd ever be sane to use a function with side-effects in a check constraint. I find it hard to visualize a case where it wouldn't be saner to put the actions in a trigger, but that doesn't mean someone else might not wish to do it. In practice, the times when check constraints are checked are predictable enough that you should be able to get away with abusing the system like that, if you wished. regards, tom lane -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs