> While thinking over Jeremy Radlow's recent problem report in
> pgsql-general, it occurs to me that it's probably wrong to implement
> referential integrity actions like ON CASCADE DELETE in AFTER
> triggers. Seems to me that this breaks the fundamental rule of
> referential integrity: if B references A then there must always be
> a matching A row for every B row. Therefore, if we delete a row from
> A we should delete the matching B row(s) before, not after, we delete
> from A. Otherwise the remainder of the transaction sees an illegal
> state of the database.
>
> Comments? How about ON UPDATE actions?
No - AFTER is right place where to do action: don't forget
about DEFERRED RI constraints for which we have to perform
check/action sometime later *after* we changed PK/FK rows.
Vadim
