Обсуждение: "on insert" rules happen before the insert?

The postgresql documentation claims that "on insert" rules are executed
after the insert. This is not happening for me. I have a rule that is being
executed even though the insert should have failed due to a foreign key check.

The rule does an insert that is failing, and the whole insert fails. So in 
this case it's not a huge problem. But I get a completely useless error 
message, and as far as I can tell there is no way to determine exactly what
caused the failure (except for the fact that I happen to know what rule
can cause that error). 

I'd like the person inserting a row that violates the foreign key check to
get a useful error message.

Is this a documentation bug? How can I get the desired behavior?

treat00@yahoo.com (Thomas Reat) writes:
> The postgresql documentation claims that "on insert" rules are executed
> after the insert. This is not happening for me. I have a rule that is being
> executed even though the insert should have failed due to a foreign key check.

The INSERT certainly happens before any rules that it triggers.  But
foreign key checks probably don't happen until all the dust has settled.
This is arguably not a bug --- there are situations where it's essential.
        regards, tom lane