Re: Mutable CHECK constraints?

On Tue, 2023-01-24 at 01:38 -0500, Tom Lane wrote:
> Laurenz Albe <laurenz.albe@cybertec.at> writes:
> > We throw an error if the expression in a CREATE INDEX statement is not IMMUTABLE.
> > But while the documentation notes that expressions in CHECK constraints are not
> > to be immutable, we don't enforce that.  Why don't we call something like
> > CheckMutability inside cookConstraint?  Sure, that wouldn't catch all abuse,
> > but it would be better than nothing.
>
> > There is of course the worry of breaking upgrade for unsafe constraints, but is
> > there any other reason not to enforce immutability?
>
> Yeah, that's exactly it, it's a historical exemption for compatibility
> reasons.  There are discussions about this in the archives, if memory
> serves ... but I'm too tired to go digging.

Thanks for the answer.  A search turned up
https://postgr.es/m/AANLkTikwFfvavEX9nDwcRD4_xJb_VAitMeP1IH4wpGIt%40mail.gmail.com

Yours,
Laurenz Albe