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Re: COPY documentation with regard to references constraints
2+ messages / 2 participants
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* Re: COPY documentation with regard to references constraints
@ 2024-10-31 12:15 Dominique Devienne <[email protected]>
  2024-10-31 12:20 ` Re: COPY documentation with regard to references constraints Bruno Wolff III <[email protected]>
  0 siblings, 1 reply; 2+ messages in thread

From: Dominique Devienne @ 2024-10-31 12:15 UTC (permalink / raw)
  To: Bruno Wolff III <[email protected]>; [email protected]

On Thu, Oct 31, 2024 at 1:04 PM Bruno Wolff III <[email protected]> wrote:
> I was unable to find any documentation clarifying if using COPY to load a
> table with rows referencing others rows in the same table, whether I
> had to worry about ordering of the input.
> What I found (in 17) is that even if the references constraint wasn't
> set as deferrable, I could have rows for children before their parents
> in the COPY data and things still worked.

AFAIK, DEFERRABLE is for temporary violations crossing statement boundaries,
to postpone the enforcement of FKs at COMMIT time of the transaction.

While a single COPY is just one statement, so whether a temporary violation
for self-referential FKs would occur would be implementation-dependent,
and thus "neither logical" nor predictable.

Applies to other statement types too.

But of course, more authoritative answers will come I'm sure. --DD






^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: COPY documentation with regard to references constraints
  2024-10-31 12:15 Re: COPY documentation with regard to references constraints Dominique Devienne <[email protected]>
@ 2024-10-31 12:20 ` Bruno Wolff III <[email protected]>
  0 siblings, 0 replies; 2+ messages in thread

From: Bruno Wolff III @ 2024-10-31 12:20 UTC (permalink / raw)
  To: Dominique Devienne <[email protected]>; +Cc: [email protected]

On Thu, Oct 31, 2024 at 13:15:34 +0100,
  Dominique Devienne <[email protected]> wrote:
>
>AFAIK, DEFERRABLE is for temporary violations crossing statement boundaries,
>to postpone the enforcement of FKs at COMMIT time of the transaction.
>
>While a single COPY is just one statement, so whether a temporary violation
>for self-referential FKs would occur would be implementation-dependent,
>and thus "neither logical" nor predictable.
>
>Applies to other statement types too.

Thanks. I needed to look more carefully under deferrable where it says 
the following:
This controls whether the constraint can be deferred. A constraint that is 
not deferrable will be checked immediately after every command.

That is pretty clear.






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