Re: Make COPY format extendable: Extract COPY TO format implementations

Álvaro Herrera писал(а) 2025-02-05 18:49:
> On 2025-Feb-03, Vladlen Popolitov wrote:
>
>> You use FORMAT option to add new formats, filling it with routine name
>> in shared library. As result any caller can call any routine in
>> PostgreSQL
>> kernel.
>> I think, it will start competition, who can find most dangerous
>> routine
>> to call just from COPY FROM command.
>
> Hah.
>
> Maybe it would be a better UI to require that COPY format handlers are
> registered explicitly before they can be used:
>
> CREATE ACCESS METHOD copy_yaml TYPE copy HANDLER copy_yaml_handler;
>
> ... and then when the FORMAT is not recognized as one of the hardcoded
> methods, we go look in pg_am for one with amtype='c' and the given
> name.
> That gives you the function that initializes the Copy state.
>
> This is convenient enough because system administrators can add COPY
> formats that anyone can use, and doesn't allow to call arbitrary
> functions via COPY.

Yes! It is what I propose. This looks much safer and already used in
access methods creation.

--
Best regards,

Vladlen Popolitov.