Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> Tom Lane wrote:
>> A BEFORE UPDATE trigger would be better, and probably hardly more
>> expensive than a wired-in facility (especially if you were willing to
>> write it in C).
> Yes. I also prefer the trigger idea to a rule because triggers are easy
> to enable and disable. It's still a lot of work for what must be a
> common want, though. Could it be done generically?
Well, you could write the trigger in C and it'd work for any table.
I think it could be as simple as a memcmp of the tuples' data areas,
since we now require padding bytes to be 0 ...
regards, tom lane