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Subject: Re: BUG #19382: Server crash at __nss_database_lookup
From: Andrey Borodin <x4mmm@yandex-team.ru>
In-Reply-To: <CAOVWO5o9YOpCTgg6FfNepCoH_6pFSa7TJ3SEWfJAoBvNOb0OdQ@mail.gmail.com>
Date: Thu, 16 Apr 2026 17:00:14 +0500
Cc: songjinzhou <tsinghualucky912@foxmail.com>,
 dllggyx <dllggyx@outlook.com>,
 pgsql-bugs <pgsql-bugs@lists.postgresql.org>
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To: surya poondla <suryapoondla4@gmail.com>
Archived-At: <https://www.postgresql.org/message-id/CC383BAA-1653-427A-975C-D27E2702E1E2%40yandex-team.ru>
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> On 9 Apr 2026, at 09:24, surya poondla <suryapoondla4@gmail.com> =
wrote:
>=20
> <0005-Fix-bug-19382-server-crash-when-ALTER-TYPE-is-used-m.patch>

I=E2=80=99ve took a look into the patch and here are some thoughts:

1. collect_composite_type_versions() does this
/* Resolve domain types to their base type */
if (typtype =3D=3D TYPTYPE_DOMAIN)
{
			attrtypid =3D getBaseType(attrtypid);
			typtype =3D get_typtype(attrtypid);
}

Only for nested types. Do we need this for root?

2. When we do this

/* Clear composite type snapshot */
rec->nCompTypes =3D 0;
rec->compTypeOids =3D NULL;
rec->compTypeVersions =3D NULL;

We also might need two pfree()s.

3. Here are few other test cases that crash with the patch.

-- Case 5: Dot assignment
create type bug19382_foo3 as (a int, b int);
create function bug19382_test_field_assign() returns record as $$
declare r bug19382_foo3;
begin
r.a :=3D 123;
r.b :=3D power(2, 30)::int4;
alter type bug19382_foo3 alter attribute b type text;
return r;
end;
$$ language plpgsql;
select bug19382_test_field_assign();
drop function bug19382_test_field_assign();
drop type bug19382_foo3 cascade;

-- Case 6: SELECT INTO field also bypasses snapshot.
create type bug19382_foo4 as (a int, b int);
create table bug19382_tbl (a int, b int);
insert into bug19382_tbl values (123, power(2, 30)::int4);
create function bug19382_test_select_into_field() returns record as $$
declare r bug19382_foo4;
begin
select a, b into r.a, r.b from bug19382_tbl;
alter type bug19382_foo4 alter attribute b type text;
return r;
end;
$$ language plpgsql;
select bug19382_test_select_into_field();
drop function bug19382_test_select_into_field();
drop table bug19382_tbl;
drop type bug19382_foo4 cascade;

Thanks!

Best regards, Andrey Borodin.=