On Tue, Mar 18, 2008 at 7:46 PM, Andrew Dunstan <[EMAIL PROTECTED]> wrote:
> > > > > > Gurjeet Singh wrote: > > On Fri, Mar 7, 2008 at 9:40 PM, Bruce Momjian <[EMAIL PROTECTED] > > <mailto:[EMAIL PROTECTED]>> wrote: > > > > > > I assume don't want a TODO for this? (Suppress UPDATE no changed > > columns) > > > > > > I am starting to implement this. Do we want to have this trigger > > function in the server, or in an external module? > > > > > > I have the trigger part of this done, in fact. What remains to be done > is to add it to the catalog and document it. The intention is to make it > a builtin as it will be generally useful. If you want to work on the > remaining parts then I will happily ship you the C code for the trigger. > > In fact, I just finished writing the C code and including it in the catalog (Just tested that it's visible in the catalog). I will test it to see if it does actually do what we want it to. I have incorporated all the suggestions above. Would love to see your code in the meantime. Here's the C code: Datum trig_ignore_duplicate_updates( PG_FUNCTION_ARGS ) { TriggerData *trigData; HeapTuple oldTuple; HeapTuple newTuple; if (!CALLED_AS_TRIGGER(fcinfo)) elog(ERROR, "trig_ignore_duplicate_updates: not called by trigger manager."); if( !TRIGGER_FIRED_BY_UPDATE(trigData->tg_event) && !TRIGGER_FIRED_BEFORE(trigData->tg_event) && !TRIGGER_FIRED_FOR_ROW(trigData->tg_event) ) { elog(ERROR, "trig_ignore_duplicate_updates: Can only be executed for UPDATE, BEFORE and FOR EACH ROW."); } trigData = (TriggerData *) fcinfo->context; oldTuple = trigData->tg_trigtuple; newTuple = trigData->tg_newtuple; if (newTuple->t_len == oldTuple->t_len && newTuple->t_data->t_hoff == oldTuple->t_data->t_hoff && HeapTupleHeaderGetNatts(newTuple->t_data) == HeapTupleHeaderGetNatts(oldTuple->t_data) && (newTuple->t_data->t_infomask & ~HEAP_XACT_MASK) == (oldTuple->t_data->t_infomask & ~HEAP_XACT_MASK) && memcmp( (char*)(newTuple->t_data) + offsetof(HeapTupleHeaderData, t_bits), (char*)(oldTuple->t_data) + offsetof(HeapTupleHeaderData, t_bits), newTuple->t_len - offsetof(HeapTupleHeaderData, t_bits) ) == 0 ) { /* return without crating a new tuple */ return PointerGetDatum( NULL ); } return PointerGetDatum( trigData->tg_newtuple ); } -- [EMAIL PROTECTED] [EMAIL PROTECTED] gmail | hotmail | indiatimes | yahoo }.com EnterpriseDB http://www.enterprisedb.com 17° 29' 34.37"N, 78° 30' 59.76"E - Hyderabad * 18° 32' 57.25"N, 73° 56' 25.42"E - Pune 37° 47' 19.72"N, 122° 24' 1.69" W - San Francisco http://gurjeet.frihost.net Mail sent from my BlackLaptop device
