On Tue, Mar 10, 2015 at 12:26 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Tue, Mar 10, 2015 at 10:23 AM, Haribabu Kommi <kommi.harib...@gmail.com> wrote: > > > > On Tue, Mar 10, 2015 at 3:09 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > > I have currently modelled it based on existing rescan for seqscan > > > (ExecReScanSeqScan()) which means it will begin the scan again. > > > Basically if the workers are already started/initialized by previous > > > scan, then re-initialize them (refer function ExecReScanFunnel() in > > > patch). > > > > > > Can you elaborate more if you think current handling is not sufficient > > > for any case? > > > > From ExecReScanFunnel function it seems that the re-scan waits till > > all the workers > > has to be finished to start again the next scan. Are the workers will > > stop the current > > ongoing task? otherwise this may decrease the performance instead of > > improving as i feel. > > > > Okay, performance-wise it might effect such a case, but I think we can > handle it by not calling WaitForParallelWorkersToFinish(), > as DestroyParallelContext() will automatically terminate all the workers. >
We can't directly call DestroyParallelContext() to terminate workers as it can so happen that by that time some of the workers are still not started. So that can lead to problem. I think what we need here is a way to know whether all workers are started. (basically need a new function WaitForParallelWorkersToStart()). This API needs to be provided by parallel-mode patch. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
