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: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Vik Fearing <vik@postgresfriends.org>, lukas.eder@gmail.com, pgsql-bugs@lists.postgresql.org, Álvaro Herrera <alvherre@kurilemu.de>
Date: 2026-03-04T06:35:56Z
Lists: pgsql-bugs

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On Tue, Mar 3, 2026 at 11:32 PM Richard Guo <guofenglinux@gmail.com> wrote:
> On Tue, Mar 3, 2026 at 10:03 AM Richard Guo <guofenglinux@gmail.com> wrote:
> > That is a good point I hadn't considered.  So I think the ideal fix is
> > to have the parser preserve the user's original JSON_ARRAY(query)
> > syntax as much as possible, and then defer the JSON_ARRAYAGG rewrite
> > trick to the planner, perhaps during expression preprocessing.

> I tried hacking on this idea to see how it would look in practice, and
> here is what I got.

Here is an updated version of the patch.  The main change is that it
now uses DirectFunctionCall1 to build the empty JSON array constant,
which is more efficient and consistent with other call sites.

- Richard

Commits

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

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