Thread

Re: Ambiguity in IS JSON description and logic

Laurenz Albe <laurenz.albe@cybertec.at> — 2025-11-18T16:37:21Z

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