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* BUG #19445: Domain DEFAULT not recorded in pg_attrdef (atthasdef false) in PostgreSQL 18.3
@ 2026-03-30 03:11 PG Bug reporting form <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: PG Bug reporting form @ 2026-03-30 03:11 UTC (permalink / raw)
To: [email protected]; +Cc: [email protected]
The following bug has been logged on the website:
Bug reference: 19445
Logged by: Xianghang Zheng
Email address: [email protected]
PostgreSQL version: 18.3
Operating system: Linux x86_64
Description:
1. PostgreSQL Version
PostgreSQL 18.3 (x86_64)
2. Operating System
Linux x86_64
3. Problem Description
When a table column uses a domain that has a DEFAULT value, the column's
pg_attribute.atthasdef is false, and no entry exists in pg_attrdef.
However, the domain default value works correctly at runtime.
This is a system catalog metadata bug.
4. Steps to Reproduce
CREATE DOMAIN my_arr_domain AS int[] DEFAULT '{}';
CREATE TABLE t (col my_arr_domain);
SELECT
a.attname,
a.atthasdef,
pg_get_expr(adbin, adrelid) as default_value
FROM pg_attribute a
LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = 't'::regclass AND a.attnum > 0;
INSERT INTO t DEFAULT VALUES;
SELECT * FROM t;
5. Actual Result
atthasdef = f
default_value is empty
But insert returns the correct default {}
6. Expected Result
atthasdef should be true
System catalog must correctly reflect the default inherited from the domain
7. Additional Information
- Domain default works correctly
- System metadata is wrong
- Affects pg_dump, information_schema, and 3rd party tools
- Bug exists in latest stable PostgreSQL 18.3
-----------------------------------------------------------------------------------------------------
postgres=# select version();
version
---------------------------------------------------------------------------------------------------------
PostgreSQL 18.3 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5
20150623 (Red Hat 4.8.5-44), 64-bit
(1 row)
postgres=#
postgres=# DROP TABLE IF EXISTS t CASCADE;
INSERT INTO t DEFAULT VALUES;
SELECT * FROM t;
DROP TABLE t;
DROP DOMAIN my_arr_domain CASCADE;DROP TABLE
postgres=# DROP DOMAIN IF EXISTS my_arr_domain CASCADE;
DROP DOMAIN
postgres=#
postgres=# CREATE DOMAIN my_arr_domain AS int[] DEFAULT '{}';
CREATE DOMAIN
postgres=#
postgres=# CREATE TABLE t (col my_arr_domain);
CREATE TABLE
postgres=#
postgres=# SELECT
postgres-# a.attname,
postgres-# a.atthasdef,
postgres-# pg_get_expr(adbin, adrelid) as default_value
postgres-# FROM pg_attribute a
postgres-# LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum =
d.adnum
postgres-# WHERE a.attrelid = 't'::regclass
postgres-# AND a.attnum > 0;
attname | atthasdef | default_value
---------+-----------+---------------
col | f |
(1 row)
postgres=#
postgres=# INSERT INTO t DEFAULT VALUES;
INSERT 0 1
postgres=# SELECT * FROM t;
col
-----
{}
(1 row)
postgres=# DROP TABLE t;
DROP TABLE
postgres=# DROP DOMAIN my_arr_domain CASCADE;
DROP DOMAIN
postgres=#
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: BUG #19445: Domain DEFAULT not recorded in pg_attrdef (atthasdef false) in PostgreSQL 18.3
@ 2026-03-30 14:56 Junwang Zhao <[email protected]>
parent: PG Bug reporting form <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Junwang Zhao @ 2026-03-30 14:56 UTC (permalink / raw)
To: [email protected]; [email protected]
On Mon, Mar 30, 2026 at 7:52 PM PG Bug reporting form
<[email protected]> wrote:
>
> The following bug has been logged on the website:
>
> Bug reference: 19445
> Logged by: Xianghang Zheng
> Email address: [email protected]
> PostgreSQL version: 18.3
> Operating system: Linux x86_64
> Description:
>
> 1. PostgreSQL Version
> PostgreSQL 18.3 (x86_64)
> 2. Operating System
> Linux x86_64
> 3. Problem Description
> When a table column uses a domain that has a DEFAULT value, the column's
> pg_attribute.atthasdef is false, and no entry exists in pg_attrdef.
> However, the domain default value works correctly at runtime.
> This is a system catalog metadata bug.
> 4. Steps to Reproduce
> CREATE DOMAIN my_arr_domain AS int[] DEFAULT '{}';
> CREATE TABLE t (col my_arr_domain);
> SELECT
> a.attname,
> a.atthasdef,
> pg_get_expr(adbin, adrelid) as default_value
> FROM pg_attribute a
> LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum = d.adnum
> WHERE a.attrelid = 't'::regclass AND a.attnum > 0;
> INSERT INTO t DEFAULT VALUES;
> SELECT * FROM t;
> 5. Actual Result
> atthasdef = f
> default_value is empty
> But insert returns the correct default {}
> 6. Expected Result
> atthasdef should be true
> System catalog must correctly reflect the default inherited from the domain
> 7. Additional Information
> - Domain default works correctly
> - System metadata is wrong
> - Affects pg_dump, information_schema, and 3rd party tools
> - Bug exists in latest stable PostgreSQL 18.3
I think this is by design, postgres correctly distinguishes between column-level
defaults (stored in pg_attrdef) and type/domain-level defaults.
>
> -----------------------------------------------------------------------------------------------------
>
>
> postgres=# select version();
> version
> ---------------------------------------------------------------------------------------------------------
> PostgreSQL 18.3 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5
> 20150623 (Red Hat 4.8.5-44), 64-bit
> (1 row)
>
> postgres=#
> postgres=# DROP TABLE IF EXISTS t CASCADE;
> INSERT INTO t DEFAULT VALUES;
> SELECT * FROM t;
>
> DROP TABLE t;
> DROP DOMAIN my_arr_domain CASCADE;DROP TABLE
> postgres=# DROP DOMAIN IF EXISTS my_arr_domain CASCADE;
> DROP DOMAIN
> postgres=#
> postgres=# CREATE DOMAIN my_arr_domain AS int[] DEFAULT '{}';
> CREATE DOMAIN
> postgres=#
> postgres=# CREATE TABLE t (col my_arr_domain);
> CREATE TABLE
> postgres=#
> postgres=# SELECT
> postgres-# a.attname,
> postgres-# a.atthasdef,
> postgres-# pg_get_expr(adbin, adrelid) as default_value
> postgres-# FROM pg_attribute a
> postgres-# LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum =
> d.adnum
> postgres-# WHERE a.attrelid = 't'::regclass
> postgres-# AND a.attnum > 0;
> attname | atthasdef | default_value
> ---------+-----------+---------------
> col | f |
> (1 row)
>
> postgres=#
> postgres=# INSERT INTO t DEFAULT VALUES;
> INSERT 0 1
> postgres=# SELECT * FROM t;
> col
> -----
> {}
> (1 row)
> postgres=# DROP TABLE t;
> DROP TABLE
> postgres=# DROP DOMAIN my_arr_domain CASCADE;
> DROP DOMAIN
> postgres=#
>
>
>
>
--
Regards
Junwang Zhao
^ permalink raw reply [nested|flat] 2+ messages in thread
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2026-03-30 03:11 BUG #19445: Domain DEFAULT not recorded in pg_attrdef (atthasdef false) in PostgreSQL 18.3 PG Bug reporting form <[email protected]>
2026-03-30 14:56 ` Junwang Zhao <[email protected]>
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