ignas(at)pow(dot)lt writes:
> [ you can sabotage foreign key constraints with triggers ]
This is not a bug, it's a "don't do that" issue. The only way to
prevent it would be to not fire triggers during FK operations, or
to somehow restrict what triggers are allowed to do, and either of
those cures would be worse than the disease.
In general, it's bad design to use a BEFORE trigger to propagate changes
to other rows; you should do that in AFTER triggers. See the
documentation.
regards, tom lane