On Fri, Jun 3, 2016 at 6:49 PM, Konstantin Knizhnik < k.knizh...@postgrespro.ru> wrote:
> > > On 03.06.2016 16:05, Amit Kapila wrote: > > On Fri, Jun 3, 2016 at 1:34 AM, Konstantin Knizhnik < > <k.knizh...@postgrespro.ru>k.knizh...@postgrespro.ru> wrote: > >> We have to add three more functions to eXtensible Transaction Manager API >> (XTM): >> >> /* >> * Calculate transaction state size. This method is invoked by >> EstimateTransactionStateSpace to copy transaction >> * state to parallel workers >> */ >> size_t (*GetTransactionStateSize)(void); >> >> /* >> * Serialize transaction state >> */ >> void (*SerializeTransactionState)(void* ctx); >> >> /* >> * Deserialize transaction state >> */ >> void (*DeserializeTransactionState)(void* ctx); >> >> > > In above proposal, are you suggesting to change the existing API's as > well, because the parameters of function pointers don't match with exiting > API's. I think it is better to consider this along with the overall XTM API. > > > Sorry, but right now I have not replaced existed functions > > EstimateTransactionStateSpace/SerializeTransactionState/StartParallelWorkerTransaction > with XTM indirect calls. If was my original intention, but these functions > access static variable CurrentTransactionState defined in xact.c. > So if user-defined TM wants to override this functions, it will have to > invoke original functions to save/restore CurrentTransactionState. > It is not convenient. > This is why three XTM functions above are now called by existed xact > funcations to save additional state, for example: > > Sounds reasonable, although one might want to have a hook for EndParallelWorkerTransaction as well. I think here larger question is whether there is a consensus on getting XTM API in core. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
