Re: minimal update - Mailing list pgsql-hackers

From Andrew Dunstan
Subject Re: minimal update
Date
Msg-id 48224B6A.9010400@dunslane.net
Whole thread Raw
In response to Re: minimal update  (Bruce Momjian <bruce@momjian.us>)
Responses Re: minimal update  (Bruce Momjian <bruce@momjian.us>)
List pgsql-hackers
Not that I know of.  I never saw Gurjeet's completed code.

cheers

andrew

Bruce Momjian wrote:
> Is there a version of this patch ready for application?
>
> ---------------------------------------------------------------------------
>
> Gurjeet Singh wrote:
>   
>> On Tue, Mar 18, 2008 at 7:46 PM, Andrew Dunstan <andrew@dunslane.net> wrote:
>>
>>     
>>>
>>>
>>>
>>> Gurjeet Singh wrote:
>>>       
>>>> On Fri, Mar 7, 2008 at 9:40 PM, Bruce Momjian <bruce@momjian.us
>>>> <mailto:bruce@momjian.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[.singh]@EnterpriseDB.com
>> singh.gurjeet@{ 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
>>     
>
>   


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