Re: Check constraints on non-immutable keys

Magnus Hagander <magnus@hagander.net> writes:
> Shouldn't we disallow anything that's not IMMUTABLE in a check constraint?

I think you'd get too many howls of pain ... also, such a restriction is
likely contrary to SQL spec.

The example seems to me to be in the category of "so don't do that"
rather than something that we need to save users from.  Yes, it's
stupid, but for example the very similar check of "a < now()"
would be perfectly safe and arguably useful.
        regards, tom lane