From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: "mark.drake@golden-hind.com" <mark.drake@golden-hind.com>,
        "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #18809: Inconsistent JSON behavoir
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References: <18809-601694c9be8a4026@postgresql.org>
 <CAKFQuwZwevnpm4QfGxU8HekDAvdjg72_z1bdiyyKaMgiXLB3BA@mail.gmail.com>
Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Wed, 12 Feb 2025 22:24:22 -0700"
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Date: Thu, 13 Feb 2025 01:06:38 -0500
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Wednesday, February 12, 2025, PG Bug reporting form <
> noreply@postgresql.org> wrote:
>> broadway=3D# select jsonb('[2,3,1]') - to_jsonb(1);
>> ERROR:  operator does not exist: jsonb - jsonb
>> LINE 1: select jsonb('[2,3,1]') - to_jsonb(1);

> This would be a feature request, not a bug report.

Indeed.  We have these cases today:

postgres=3D# \do -
                                                                 List of o=
perators
   Schema   | Name |        Left arg type        |       Right arg type   =
     |         Result type         |             Description             =

------------+------+-----------------------------+------------------------=
-----+-----------------------------+-------------------------------------
...
 pg_catalog | -    | jsonb                       | integer                =
     | jsonb                       | delete array element
 pg_catalog | -    | jsonb                       | text                   =
     | jsonb                       | delete object field
 pg_catalog | -    | jsonb                       | text[]                 =
     | jsonb                       | delete object fields
...

These are already less than consistent, for example this is allowed:

postgres=3D# select jsonb('[2,3,1]') - 'foo'::text;
 ?column?  =

-----------
 [2, 3, 1]
(1 row)

but this not so much:

postgres=3D# select jsonb('{"a": 1, "b": 2}') - 1;
ERROR:  cannot delete from object using integer index

To invent jsonb - jsonb, you'd need to define its behavior for
every possible JSON structure on each side.  I foresee plenty of
bikeshedding.

			regards, tom lane