Horton

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

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Nathan Bossart <nathandbossart@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: 2026-05-01T00:26:32Z
Lists: pgsql-bugs 
On Fri, May 1, 2026 at 7:05 AM Melanie Plageman
<melanieplageman@gmail.com> wrote:
> 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.

Thank you, Nathan and Melanie.  I now have two of the three RMT
approvals, so I believe I'm good to go.  Will commit this shortly.

- Richard

Commits

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

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