Re: plpgsql error handling bug

Tom Lane wrote:

> Ivan-Sun1(at)mail(dot)ru writes:
>
>>I found a bug in the behaviour of plpgsql error handling system
>>while trying to handle foreign key violation exception.
>
>
> This is not a bug in the exception system.
>
> The problem is that FK constraints are enforced by triggers that do not
> fire until the end of the outer statement (that is, the SELECT that
> calls the plpgsql function). So by the time the constraint error is
> raised, we have long since exited the exception structure.
>
> There has been some talk of changing trigger firing rules to make this
> sort of thing behave more intuitively inside functions, but it hasn't
> happened yet.
>
> Maybe we should think about doing something about this for 8.0? It's a
> larger behavioral change than I like to think about for post-beta, but
> (a) the exception mechanism's usefulness is certainly going to be
> severely limited if it can't catch FK errors; (b) 8.0 seems like a
> more appropriate time to introduce backwards-incompatibilities than
> future 8.x releases.

Considering also that if you fix the BUG #1231 then 8.0 have already some
backwards-incompatibilities so one more is mitigated by the other one.

Regards
Gaetano Mendola