Sender: Heikki Linnakangas <hlinnaka@gmail.com>
From: Heikki Linnakangas <hlinnaka@iki.fi>
Date: Fri, 05 Jun 2026 12:04:52 +0300
To: pgsql-hackers@lists.postgresql.org, Chao Li <li.evan.chao@gmail.com>,
 Postgres hackers <pgsql-hackers@lists.postgresql.org>
CC: Andrew Dunstan <andrew@dunslane.net>,
 jian he <jian.universality@gmail.com>
Subject: Re: Fix domain fast defaults on empty tables
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On 5 June 2026 10:48:00 EEST, Chao Li <li=2Eevan=2Echao@gmail=2Ecom> wrote=
:
>Hi,
>
>I tested "[a0b6ef29a] Enable fast default for domains with non-volatile c=
onstraints"=2E After tracing some cases from the regression tests, I came u=
p with this test case and found a bug:
>```
>evantest=3D# create domain d_div as int check (1 / (value - 1) > 0);
>CREATE DOMAIN
>evantest=3D# create table t (a int);
>CREATE TABLE
>evantest=3D# alter table t add column b d_div default 1;
>ERROR:  division by zero
>```
>
>It looks like errors inside the CHECK expression itself, such as the int4=
div division-by-zero in this test, are still hard errors that can fail the =
ALTER TABLE command=2E

It seems totally reasonable to get an error in that case=2E '1' is not a v=
alid value for the datatype, whether or not there are any rows in the table=
=2E

- Heikki