Message-ID: <109c4b7c676cfde0d9c8666fa2c1f0063453df18.camel@cybertec.at>
Subject: Re: Ambiguity in IS JSON description and logic
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: r314tive <tanswis42@gmail.com>, "David G. Johnston"
	 <david.g.johnston@gmail.com>
Cc: Kirk Parker <khp@equatoria.us>, vavankaru@gmail.com,
	pgsql-docs@lists.postgresql.org
Date: Tue, 18 Nov 2025 17:37:21 +0100
In-Reply-To: 
 <CALCfnurPwdZU3T4tWeSAgn-JcVVqQdmDoMmO5DqHKi0QnS=-GA@mail.gmail.com>
References: <174238647361.682.12732328104350596711@wrigleys.postgresql.org>
	 <CANwZ8r=qtW3EfrzMrEB=xRoxePmx=JLUC8MvEK68kRCrfrQ4_g@mail.gmail.com>
	 <CANwZ8rmj7Mr_ZaZsfH5cx5uNzRZ91aHaRWe=ViJGO=U7rKjFCQ@mail.gmail.com>
	 <CAKFQuwZY8XS7EaF9nqq77G+5cnxhiwcDqa7tcYs-HRh1Wj5YDQ@mail.gmail.com>
	 <CALCfnurPwdZU3T4tWeSAgn-JcVVqQdmDoMmO5DqHKi0QnS=-GA@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) 
MIME-Version: 1.0
Archived-At: 
 <https://www.postgresql.org/message-id/109c4b7c676cfde0d9c8666fa2c1f0063453df18.camel%40cybertec.at>
Precedence: bulk

On Tue, 2025-11-18 at 16:55 +0500, r314tive wrote:
> Based on this discussion, I=E2=80=99ve prepared a small documentation pat=
ch that
> tries to clarify the behavior of the IS JSON ... UNIQUE KEYS clause.
>=20
> The patch explains that:
> - the WITH/WITHOUT UNIQUE KEYS clause controls an additional test on
> =C2=A0 duplicate object keys,
> - WITH UNIQUE KEYS requires that no object contained in the expression
> =C2=A0 (recursively) have duplicate keys, and
> - WITHOUT UNIQUE KEYS, which is also the default, just disables this
> =C2=A0 additional test and does not require duplicates to be present.
>=20
> Patch is attached.

I don't think that the patch is really an improvement.  To me, the original
wording contains all the important information.  The patch it somewhat
repetetive and contains unnecessary detail.  For example, I can see from
the syntax diagram that I can use WITHOUT UNIQUE KEYS, and I have no
trouble guessing what that means.

Perhaps it would be enough to add something like "*recursively* checks for
duplicate keys" or "checks for duplicate keys *on any nesting level*".

Yours,
Laurenz Albe