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Subject: BUG #19417: '\dD' fails to list user-defined domains that shadow built-in type names (e.g., 'numeric')
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: zhangyc0706@gmail.com
Reply-To: zhangyc0706@gmail.com, pgsql-bugs@lists.postgresql.org
Date: Thu, 26 Feb 2026 07:21:05 +0000
Message-ID: <19417-401f33ed14f3d4d5@postgresql.org>
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Archived-At: <https://www.postgresql.org/message-id/19417-401f33ed14f3d4d5%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19417
Logged by:          yuanchao zhang
Email address:      zhangyc0706@gmail.com
PostgreSQL version: 18.2
Operating system:   windows 10
Description:       =20

Hi,
I created a domain object named `numeric` using the following SQL:
`CREATE DOMAIN numeric AS NUMERIC(12,2) DEFAULT 0 CHECK (VALUE >=3D 0);`
After executing this SQL, it indicated that the domain was created
successfully.
However, when I executed `\dD` in psql, I found that the domain I just
created could not be displayed.
Therefore, I queried `pg_type` using the following statement:
`SELECT
    n.nspname AS schema_name,
    t.typname AS domain_name,
    pg_catalog.format_type(t.typbasetype, t.typtypmod) AS base_type,
    t.typnotnull AS not_null,
    t.typdefault AS default_value,
        t.typtype
FROM pg_catalog.pg_type t
JOIN pg_catalog.pg_namespace n ON n.oid =3D t.typnamespace
WHERE t.typtype =3D 'd'
ORDER BY schema_name, domain_name;`
The execution result of this SQL statement shows the domain object I just
created.
I then created a domain using a different name, as shown in the following
SQL:
`CREATE DOMAIN numeric_t1 AS NUMERIC(12,2) DEFAULT 0 CHECK (VALUE >=3D 0);`
After executing the SQL, I found that this domain could be shown both in
`pg_type` and through a `\dD` query.
Of course, I know that using the name numeric as the domain name isn't
particularly reasonable,
 but I didn't receive any prompts during the creation process.
Therefore, I think that since the creation was successful, it should be
displayed via `\dD`.
Because I checked the documentation regarding the use of '\dD', and there
was no explanation for this special case.

Thanks.