Re: Get current trasanction id

Joachim Zobel napisał(a):
> Am Mo, den 27.12.2004 schrieb Marek Lewczuk um 20:54:
>
>>Michael Fuhr napisał(a):
>>
>>>Why do you want the transaction ID?  What problem are you trying
>>>to solve?
>>>
>>
>>I've already solved the problem - I found somewhere on the web a very
>>simple C function, which returns transaction id. I need transaction id
>>for plperl functions setVar, getVar (using $_SHARED array). Functions
>>can write/read variables which are available either for connection or
>>transaction.
>
>
> It would be nice to have that in pgplsql. I once needed a transaction Id
> in oracle for a historisation trigger. It saves before copies of the
> modified records on a per transaction basis.
As I wrote before you can have it in plpgsql - you just need to install
special c function as e.g getCurrentTransactionId() and you will be able
to get id from within plpgsql - but I agree that this function should be
in base SQL functions or at least in contrib modules.

C function is very simple:

getcurrenttransactionid.c:
#include "postgres.h"
#include "access/xact.h"

Datum getcurrenttransactionid(PG_FUNCTION_ARGS)
{
         TransactionId xid = GetCurrentTransactionId();
         PG_RETURN_INT32((int32) xid);
}


getcurrenttransactionid.sql:
SET search_path = public;

CREATE FUNCTION getCurrentTransactionId()
    RETURNS integer
    AS 'MODULE_PATHNAME'
    LANGUAGE 'c';



Regards,

Marek Lewczuk