Re: Problem with trigger makes Detail record be invalid

2018-04-19 15:57 GMT-03:00 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>
> 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.
>

Yeap... it's already mentioned in stackoverflow in ptbr sometime ago [1]
with a reproducible test case.

> (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.)
>

We don't have it properly documented... at the time I answered this
question on pt-br stackoverflow I noticed the lack o documentation and
unfortunately I completely forgot to propose a small patch for it.

Regards,

[1]
https://pt.stackoverflow.com/questions/256115/postgresql-foreign-keys-falhando/256398#256398

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