Horton

Re: BUG #19418: SQL/JSON JSON_VALUE() does not conform to ISO/IEC 9075-2:2023(E) 6.34 <JSON value constructor>

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Richard Guo <guofenglinux@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Amit Langote <amitlangote09@gmail.com>, Vik Fearing <vik@postgresfriends.org>, lukas.eder@gmail.com, pgsql-bugs@lists.postgresql.org, rmt@lists.postgresql.org, Álvaro Herrera <alvherre@kurilemu.de>, Heikki Linnakangas <hlinnaka@iki.fi>
Date: 2026-04-30T22:04:54Z
Lists: pgsql-bugs 
On Fri, Apr 24, 2026 at 3:58 PM Nathan Bossart <nathandbossart@gmail.com> wrote:
>
> On Thu, Apr 23, 2026 at 09:55:10AM +0900, Richard Guo wrote:
> >> Hi RMT,
> >>
> >> I'd like to commit a fix for JSON_ARRAY(subquery) behavior that
> >> involves a user-visible incompatibility, and would appreciate your
> >> go/no-go since we're past feature freeze.
> >>
> >> Summary:
> >>
> >> - JSON_ARRAY(SELECT ...) currently returns NULL over an empty result
> >> set, but the SQL/JSON standard requires it to return '[]'.  Fixing
> >> this changes user-visible output.
> >>
> >> - The same patch also fixes a deparsing issue: views defined with
> >> JSON_ARRAY(SELECT ...) are dumped back as the internal JSON_ARRAYAGG
> >> rewrite instead of the original syntax.
>
> I am fine with committing this for v19, assuming there is consensus on the
> patch content.
>
> Heikki/Melanie: Any objections?

Nope. I'm +1 on committing this now. 19 is unreleased -- I see no
reason to wait a year.

- Melanie

Commits

  1. Enforce RETURNING typmod for empty-set JSON_ARRAY(query)

  2. Fix JSON_ARRAY(query) empty set handling and view deparsing