Re: Why does jsonb_set() remove non-mentioned keys?

On Thursday, July 4, 2019, Gianni Ceccarelli <dakkar(at)thenautilus(dot)net> wrote:

> Some experimentation:
>
> > \pset null '((null))'
>
> > select jsonb_set('{"foo":1}'::jsonb,'{bar}','null'::jsonb,true);
> ┌─────────────────────────┐
> │ jsonb_set │
> ├─────────────────────────┤
> │ {"bar": null, "foo": 1} │
> └─────────────────────────┘

No SQL null, ok

>
>
> > select jsonb_set('{"foo":1}'::jsonb,'{bar}',to_jsonb(null::text),true);
> ┌───────────┐
> │ jsonb_set │
> ├───────────┤
> │ ((null)) │
> └───────────┘

Sql null poisons the expression and so sql null is the result

>
> That's a bit weird already. Also:
>
> > select null::jsonb;
> ┌──────────┐
> │ jsonb │
> ├──────────┤
> │ ((null)) │
> └──────────┘
>
>
Sql null

> > select 'null'::jsonb;
> ┌───────┐
> │ jsonb │
> ├───────┤
> │ null │
> └───────┘
>
>
Json null

> > select to_jsonb(null::int);
> ┌──────────┐
> │ to_jsonb │
> ├──────────┤
> │ ((null)) │
> └──────────┘
>
>
Sql null poisons the function call which immediately returns sql null

> > select to_jsonb('null'::text);
> ┌──────────┐
> │ to_jsonb │
> ├──────────┤
> │ "null" │
> └──────────┘
>
>
Json null

> I'm sharing Thomas's confusion…
>
>
Sql null and json null are represented differently; strict functions with
sql null inputs yield sql null output without even executing the function

David J.