Feedback-ID: ia2694551:Fastmail
Date: Sat, 10 Dec 2022 13:20:13 +0100
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andrew Dunstan <andrew@dunslane.net>,
	Andres Freund <andres@anarazel.de>,
	Alexander Korotkov <aekorotkov@gmail.com>,
	Robert Haas <robertmhaas@gmail.com>,
	"David G. Johnston" <david.g.johnston@gmail.com>,
	Corey Huinker <corey.huinker@gmail.com>,
	Joe Conway <mail@joeconway.com>,
	Nikita Glukhov <n.gluhov@postgrespro.ru>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Error-safe user functions
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On 2022-Dec-09, Tom Lane wrote:

> I think though that it might be okay to just define this as
> Not Our Problem.  Although we don't seem to try to enforce it,
> non-immutable domain check constraints are strongly deprecated
> (the CREATE DOMAIN man page says that we assume immutability).
> And not throwing errors is something that we usually consider
> should ride along with immutability.  So I think it might be
> okay to say "if you want soft error treatment for a domain,
> make sure its check constraints don't throw errors".

I think that's fine.  If the user does, say "CHECK (value > 0)" and that
results in a soft error, that seems to me enough support for now.  If
they want to do something more elaborate, they can write C functions.
Maybe eventually we'll want to offer some other mechanism that doesn't
require C, but let's figure out what the requirements are.  I don't
think we know that, at this point.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"Estoy de acuerdo contigo en que la verdad absoluta no existe...
El problema es que la mentira sí existe y tu estás mintiendo" (G. Lama)