Re: TRUNCATE ONLY with foreign keys and triggers disabled

On Mon, 14 Apr 2025, Adrian Klaver wrote:

> On 4/14/25 08:20, Dimitrios Apostolou wrote:
>> On Mon, 14 Apr 2025, Adrian Klaver wrote:
>>
>>> On 4/14/25 08:07, Laurenz Albe wrote:
>>>>  On Mon, 2025-04-14 at 17:05 +0200, Dimitrios Apostolou wrote:
>>>>>  I meant the *referencing* table has just been
>>>>>  populated. I'm trying to delete the *referenced* table and I get the
>>>>>  error.
>>>>
>>>>  That would break the foreign key constraint, right?
>>>>  PostgreSQL cannot allow that.
>>>
>>> I believe the OP is disabling all triggers including system ones if I
>>> follow
>>> correctly and possibly running a foul of;
>>>
>>> https://www.postgresql.org/docs/current/sql-altertable.html
>>>
>>> " Disabling or enabling internally generated constraint triggers requires
>>> superuser privileges; it should be done with caution since of course the
>>> integrity of the constraint cannot be guaranteed if the triggers are not
>>> executed."
>>
>> Exactly that. I learned this from pg_restore --disable-triggers, as a way
>> to speed-up insertion.
>>
>> Since triggers are disabled, I assumed that postgresql shouldn't care
>> about referential integrity in TRUNCATE.
>
> I'm going to say the depends on order of execution. Without seeing the code
> changes you have done there is really no way to determine what the exact
> issue is.

Sent patch here:

https://www.postgresql.org/message-id/flat/4589087c-ec6f-4407-1f82-6cb2e681ac0a%40gmx.net

The reason I first sent here (pgsql-general) is that I wondered if the
error is just an implementation shortcoming without deeper reasons, thus
it would be achievable to try to fix it myself.

Dimitris