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Subject: BUG #19444: conkey field empty for domain NOT NULL constraint in pg_constraint (18.3)
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: zheng_xianghang@163.com
Reply-To: zheng_xianghang@163.com, pgsql-bugs@lists.postgresql.org
Date: Mon, 30 Mar 2026 03:10:45 +0000
Message-ID: <19444-21f73da373fc0f58@postgresql.org>
Auto-Submitted: auto-generated
Archived-At: <https://www.postgresql.org/message-id/19444-21f73da373fc0f58%40postgresql.org>
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The following bug has been logged on the website:

Bug reference:      19444
Logged by:          Xianghang Zheng
Email address:      zheng_xianghang@163.com
PostgreSQL version: 18.3
Operating system:   Linux x86_64
Description:       =20

When creating a domain with a NOT NULL constraint, the conkey field in
pg_constraint remains empty. This is inconsistent with table-level NOT
NULL constraints, which correctly populate the conkey field.

Version: PostgreSQL 18.3 (x86_64)
Platform: Linux x86_64

Steps to Reproduce:
-------------------
CREATE DOMAIN my_domain AS text NOT NULL;

SELECT conname, contype, conkey, contypid::regtype
FROM pg_constraint
WHERE contypid =3D 'my_domain'::regtype;

Actual Result:
--------------
      conname       | contype | conkey | contypid
--------------------+---------+--------+-----------
 my_domain_not_null | n       |        | my_domain
(1 row)

Expected Result:
----------------
The conkey field should contain {1} (the first and only column of the
domain):

      conname       | contype | conkey | contypid
--------------------+---------+--------+-----------
 my_domain_not_null | n       | {1}    | my_domain

Additional Information:
-----------------------
- The NOT NULL constraint works correctly (rejects NULL values)
- The issue is only with the system catalog metadata
- This may affect tools like pg_dump, pg_upgrade, or extensions that rely
  on the conkey field for domain constraints
- Table-level NOT NULL constraints correctly populate conkey:
 =20
  CREATE TABLE test_table (id text NOT NULL);
  SELECT conname, contype, conkey FROM pg_constraint
  WHERE conrelid =3D 'test_table'::regclass;
 =20
  Result: test_table_id_not_null | n | {1}

Please let me know if you need any additional information or testing.