Andrew Dunstan <[EMAIL PROTECTED]> writes: > Tom Lane wrote: >> 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); Close, but I think you also need to take care to compare natts and the null bitmaps (if any). Might be worth comparing OIDs too, though AFAIR there is no mechanism for substituting a different OID during UPDATE. Probably the easiest coding is to memcmp all the way from offsetof(t_bits) to t_len, after comparing natts and the HASNULL and HASOID flags. > Also, when did we first require padding bytes to be 0? The 8.3 varvarlena patch is what requires it, but in practice heap_formtuple has always started with a palloc0, so I think it would work a long ways back. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match