Tom Lane wrote:
Andrew Dunstan <[EMAIL PROTECTED]> 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 ...
Something like this fragment?
newtuple = trigdata->tg_newtuple;
oldtuple = trigdata->tg_trigtuple;
rettuple = newtuple;
if (newtuple->t_len == oldtuple->t_len &&
newtuple->t_data->t_hoff == oldtuple->t_data->t_hoff &&
memcmp(GETSTRUCT(newtuple),GETSTRUCT(oldtuple),
newtuple->t_len - newtuple->t_data->t_hoff) == 0)
rettuple = NULL;
return PointerGetDatum(rettuple);
Also, when did we first require padding bytes to be 0?
cheers
andrew
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