Re: BUG #19589: JSON_QUERY rejects domain-over-bytea input when using FORMAT JSON ENCODING UTF8.

On Thu Jul 30, 2026 at 1:40 PM CDT, PG Bug reporting form wrote:
> The following bug has been logged on the website:
>
> Bug reference: 19589
> Logged by: Yuxiao Guo
> Email address: dllggyx(at)outlook(dot)com
> PostgreSQL version: 18.4
> Operating system: Ubuntu 20.04 x86-64, docker image postgres:18.4
> Description:
>
> 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

Thanks for the report. I am currently taking a look at this. I have
reproduced the issue and am working on a fix.

--
Tristan Partin
PostgreSQL Contributors Team
AWS (https://aws.amazon.com)