| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Mutable CHECK constraints? |
| Date: | 2023-01-24 23:24:00 |
| Message-ID: | f4495237cb3e6bf79aeef43bcf8d371394d2d201.camel@cybertec.at |
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| Lists: | pgsql-hackers |
On Tue, 2023-01-24 at 01:38 -0500, Tom Lane wrote:
> Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)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
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