Thread: BUG #18809: Inconsistent JSON behavoir

The following bug has been logged on the website:

Bug reference:      18809
Logged by:          Mark Drake
Email address:      mark.drake@golden-hind.com
PostgreSQL version: 17.0
Operating system:   Linux
Description:

broadway=# select jsonb('[2,3,1]') @> to_jsonb(1);
 ?column?
----------
 t
(1 row)


broadway=# select jsonb('[2,3,1]') @> to_jsonb(4);
 ?column?
----------
 f
(1 row)


broadway=# select jsonb('[2,3,1]') @> to_jsonb(4);
 ?column?
----------
 f
(1 row)


broadway=# select jsonb('[2,3,1]') - 1;
 ?column?
----------
 [2, 1]
(1 row)


broadway=#
broadway=# 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);
                                ^
HINT:  No operator matches the given name and argument types. You might need
to add explicit type casts.
broadway=#

Given that the first statement show the array contains an element that
matches to_jsonb(1) the fourth statement should delete the third ( index 2)
item from the array, not return an argument type mismatch. This would solve
the problem of not being able to delete from a JSON integer array by value

The following bug has been logged on the website:

Bug reference:      18809
Logged by:          Mark Drake
Email address:      mark.drake@golden-hind.com
PostgreSQL version: 17.0
Operating system:   Linux
Description:       

broadway=#
broadway=# 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);
                                ^
HINT:  No operator matches the given name and argument types. You might need
to add explicit type casts.
broadway=#

Given that the first statement show the array contains an element that
matches to_jsonb(1) the fourth statement should delete the third ( index 2)
item from the array, not return an argument type mismatch. This would solve
the problem of not being able to delete from a JSON integer array by value

"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Wednesday, February 12, 2025, PG Bug reporting form <
> noreply@postgresql.org> wrote:
>> broadway=# 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=# \do -
                                                                 List of operators
   Schema   | Name |        Left arg type        |       Right arg type        |         Result type         |
  Description              

------------+------+-----------------------------+-----------------------------+-----------------------------+-------------------------------------
...
 pg_catalog | -    | jsonb                       | integer                     | jsonb                       | delete
arrayelement 
 pg_catalog | -    | jsonb                       | text                        | jsonb                       | delete
objectfield 
 pg_catalog | -    | jsonb                       | text[]                      | jsonb                       | delete
objectfields 
...

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

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

but this not so much:

postgres=# 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