Re: Fix domain fast defaults on empty tables

On 5 June 2026 10:48:00 EEST, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
>Hi,
>
>I tested "[a0b6ef29a] Enable fast default for domains with non-volatile constraints". After tracing some cases from the regression tests, I came up with this test case and found a bug:
>```
>evantest=# create domain d_div as int check (1 / (value - 1) > 0);
>CREATE DOMAIN
>evantest=# create table t (a int);
>CREATE TABLE
>evantest=# 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 int4div division-by-zero in this test, are still hard errors that can fail the ALTER TABLE command.

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

- Heikki