Re: Problem with trigger makes Detail record be invalid

Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> writes:
> On 04/19/2018 10:55 AM, PegoraroF10 wrote:
>> Is this a bug or it´s mine responsability to check that trigger result ?

> Without seeing exactly what the trigger function on Detail is doing that
> is not answerable.

I think the OP is complaining because his misimplemented trigger can break
the consistency of the foreign key constraint. That is not a bug, it's
an intentional design decision: triggers are lower-level than foreign key
enforcement queries, and fire during such queries. It's easy to construct
examples where people would be very unhappy if this were not so, because
then FK-driven updates would not be seen by the table's triggers. It does
mean that you have to be careful when writing a trigger.

(I'm not sure that this issue is adequately documented, though.
I'd have expected to find something about it in triggers.sgml and/or
create_trigger.sgml, but in a quick look neither of them mentions foreign
keys.)

regards, tom lane