Обсуждение: Unexpected behavior of jsonb_set() with a `null` value

Марк schrieb am 12.09.2019 um 12:55:
> With `jsonb_set()`, when `new_value` is `NULL`, the function would **erase the whole object**:
> 
> postgres=# SELECT jsonb_set('{"something":1}'::jsonb, '{language}', null, true);         
> jsonb_set  
> -----------
>  
> (1 row)
> 
> This is really dangerous for it may lead to data loss. Imaging the `new_value` argument being a function which
returns`NULL` values in some cases.
 
> The expected behavior is, perhaps, to convert an SQL `NULL` value to JSONB null value: 'null'::jsonb
> This way no data would be lost.
> 
> Or at the very least, this behavior should be documented.

I have asked the same: https://www.postgresql.org/message-id/flat/qfkua9%242q0e%241%40blaine.gmane.org

In short: not a bug ;) 

Thomas Kellerer <spam_eater@gmx.net> writes:
> Марк schrieb am 12.09.2019 um 12:55:
>> The expected behavior is, perhaps, to convert an SQL `NULL` value to JSONB null value: 'null'::jsonb

> I have asked the same: https://www.postgresql.org/message-id/flat/qfkua9%242q0e%241%40blaine.gmane.org

There are other more-apropos threads in the archives, though I'm too
lazy to go find them right now.  IMO the problem here is an assumption
that SQL NULL should be interchangeable with a JSON NULL.  It's not,
and we don't intend to make it so, because (a) the definitional quagmire
that would result is bottomless; (b) people asking for this are generally
trying to use SQL NULL as a live data value, which is almost always just
a bad idea.

            regards, tom lane