Re: ALTER DOMAIN ADD NOT NULL NOT VALID

[jian he]

On Thu, Aug 14, 2025 at 5:02 PM Kirill Reshke <reshkekir...@gmail.com> wrote:
>
> I have few observations.
> One is whether we should now support CREATE DOMAIN ... NOT NULL NOT
> VALID syntax? This could be a separate patch though.
>

in gram.y:

CreateDomainStmt:
            CREATE DOMAIN_P any_name opt_as Typename ColQualList
                {
                    CreateDomainStmt *n = makeNode(CreateDomainStmt);

                    n->domainname = $3;
                    n->typeName = $5;
                    SplitColQualList($6, &n->constraints, &n->collClause,
                                     yyscanner);
                    $$ = (Node *) n;
                }
        ;

ColConstraintElem:
            NOT NULL_P opt_no_inherit
                {
                    Constraint *n = makeNode(Constraint);
                    n->contype = CONSTR_NOTNULL;
                    n->location = @1;
                    n->is_no_inherit = $3;
                    n->is_enforced = true;
                    n->skip_validation = false;
                    n->initially_valid = true;
                    $$ = (Node *) n;
                }
            | NULL_P
                {
                    Constraint *n = makeNode(Constraint);

                    n->contype = CONSTR_NULL;
                    n->location = @1;
                    $$ = (Node *) n;
                }

CREATE DOMAIN use ColConstraintElem.
that's why we do not support syntax:
``create domain t1 as int not null not valid;``

we also do not support column constraints NOT NULL NOT VALID.
Like
``create table t(a int not null not valid);``
will error out.
so I guess it's fine to not support it?


opt_not_valid:    NOT VALID                            {  $$ = true; }
            | /* EMPTY */                                        {  $$
= false; }
        ;
ColConstraintElem:
            NOT NULL_P opt_no_inherit opt_not_valid
                {
                    Constraint *n = makeNode(Constraint);

                    n->contype = CONSTR_NOTNULL;
                    n->location = @1;
                    n->is_no_inherit = $3;
                    n->is_enforced = true;
                    // n->skip_validation = false;
                    // n->initially_valid = true;
                    n->skip_validation = $4;

                    n->initially_valid = !n->skip_validation;

                    $$ = (Node *) n;
                }

the above change will produce error
/usr/bin/bison -Wno-deprecated -o src/backend/parser/gram.c -d
../../Desktop/pg_src/src9/postgres/src/backend/parser/gram.y
../../Desktop/pg_src/src9/postgres/src/backend/parser/gram.y: error:
shift/reduce conflicts: 1 found, 0 expected
../../Desktop/pg_src/src9/postgres/src/backend/parser/gram.y: note:
rerun with option '-Wcounterexamples' to generate conflict
counterexamples

so currently I don't know how to support syntax
``create domain t1 as int not null not valid;``

I also found it's hard to psql-tab-complete for
 'alter domain ... add constraint .. not null' with 'not valid'.