Re: minimal update

Is there a version of this patch ready for application?

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Gurjeet Singh wrote:
> On Tue, Mar 18, 2008 at 7:46 PM, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
>
> >
> >
> >
> >
> >
> > Gurjeet Singh wrote:
> > > On Fri, Mar 7, 2008 at 9:40 PM, Bruce Momjian <bruce(at)momjian(dot)us
> > > <mailto:bruce(at)momjian(dot)us>> 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 );
> }
>
>
>
> --
> gurjeet[(dot)singh](at)EnterpriseDB(dot)com
> singh(dot)gurjeet(at){ gmail | hotmail | indiatimes | yahoo }.com
>
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--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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