Hello,
On Sat, Oct 19, 2019 at 12:52 AM Pavel Stehule <[email protected]> wrote:
>
>
>
> so 19. 10. 2019 v 7:41 odesílatel David G. Johnston
> <[email protected]> napsal:
>>
>> On Friday, October 18, 2019, Pavel Stehule <[email protected]> wrote:
>>
>>>
>>> Probably there will be some applications that needs NULL result in
>>> situations when value was not changed or when input value has not expected
>>> format. Design using in Postgres allows later customization - you can
>>> implement with COALESCE very simply behave that you want (sure, you have to
>>> know what you do). If Postgres implement design used by MySQL, then there
>>> is not any possibility to react on situation when update is not processed.
>>
>>
>> A CASE expression seems like it would work well for such detection in the
>> rare case it is needed. Current behavior is unsafe with minimal or no
>> redeeming qualities. Change it so passing in null raises an exception and
>> make the user decide their own behavior if we don’t want to choose one for
>> them.
>
>
> How you can do it? Buildn functions cannot to return more than one value. The
> NULL is one possible signal how to emit this informations.
>
> The NULL value can be problem everywhere - and is not consistent to raise
> exception somewhere and elsewhere not.
>
> I agree so the safe way is raising exception on NULL. Unfortunately,
> exception handling is pretty expensive in Postres (more in write
> transactions), so it should be used only when it is really necessary.
I would say that any thing like
update whatever set column=jsonb_set(column, '{foo}', NULL)
should throw an exception. It should do, literally, *anything* else
but blank that column.
Ariadne
