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Subject: BUG #19589: JSON_QUERY rejects domain-over-bytea input when using
 FORMAT JSON ENCODING UTF8.
To: pgsql-bugs@lists.postgresql.org
From: PG Bug reporting form <noreply@postgresql.org>
Cc: dllggyx@outlook.com
Reply-To: dllggyx@outlook.com, pgsql-bugs@lists.postgresql.org
Date: Thu, 30 Jul 2026 10:29:19 +0000
Message-ID: <19589-edd0b3b861601fef@postgresql.org>
Auto-Submitted: auto-generated
Archived-At: 
 <https://www.postgresql.org/message-id/19589-edd0b3b861601fef%40postgresql.org>
Precedence: bulk

The following bug has been logged on the website:

Bug reference:      19589
Logged by:          Yuxiao Guo
Email address:      dllggyx@outlook.com
PostgreSQL version: 18.4
Operating system:   Ubuntu 20.04 x86-64, docker image postgres:18.4
Description:       =20

Query A and Query B are equivalent, but while JSON_QUERY(... FORMAT JSON
ENCODING UTF8 ...) accepts a direct bytea input, it incorrectly rejects a
domain-over-bytea input with the error JSON ENCODING clause is only allowed
for bytea input type.

PoC:

```sql
CREATE DOMAIN d_json_bytea AS bytea;

-- Query A
SELECT JSON_QUERY(convert_to(txt, 'utf8') FORMAT JSON ENCODING UTF8, '$') AS
j
FROM (VALUES ('[1,2]')) AS src(txt);

-- Query B
SELECT JSON_QUERY(b FORMAT JSON ENCODING UTF8, '$') AS j
FROM (
  SELECT convert_to(txt, 'utf8')::d_json_bytea AS b
  FROM (
    SELECT txt
    FROM (
      SELECT '[1,2]'::text AS txt
      UNION ALL
      SELECT '[9,9]'::text WHERE false
    ) AS u
    WHERE txt LIKE '[%'
  ) AS filtered
) AS typed;

```

Result of Query A:
   j
--------
 [1, 2]
(1 row)

Result of Query B:
ERROR:  JSON ENCODING clause is only allowed for bytea input type
LINE 1: SELECT JSON_QUERY(b FORMAT JSON ENCODING UTF8, '$') AS j