Re: UPDATE with invalid domain constraint

On Tue, Aug 19, 2025 at 10:08 PM jian he <jian(dot)universality(at)gmail(dot)com> wrote:
>

> drop table if exists dt1;
> drop domain if exists d1;
> create domain d1 as int;
> create table dt1(i int, c d1);
> insert into dt1 values(1,2);
> alter domain d1 add constraint cc check(value <> 2) not valid;
>

> update dt1 set i = i + 1;
> update dt1 set c = c;
> update dt1 set i = i + 1, c = c;
> update dt1 set i = i + 1, c = c::d1;
>
> Should the four statements above result in an error?
> This only happens with UPDATE, since INSERT will check with domain
> invalid constraints.

the main idea is that
if we find out that a Var Node type is domain with invalid constraint
then we convert the
Var to CoerceToDomain node.

explain (verbose, costs off) update dt1 set i = i + 1;
QUERY PLAN
----------------------------------
Update on public.dt1
-> Seq Scan on public.dt1
Output: (i + 1), c, ctid
(3 rows)

as you can see from the "Output:", column "c" is also here,
In rewriteTargetListIU, In rewriteTargetListIU, I use makeTargetEntry to produce
a new TargetEntry for column c, set its expr to a CoerceToDomain node, and set
resjunk to true.