> On Jun 14, 2018, at 9:19 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> anyone who wants a BEFORE trigger has a good reason
> for wanting it.
I have used before triggers to enforce the immutability of a column.
i.e.
if (new.member_key != old.member_key) then
raise exception 'Unable to change member_key, column is immutable';
end if
;