On Fri, Dec 5, 2014 at 8:43 PM, Stephen Frost <sfr...@snowman.net> wrote: > > José, > > * José Luis Tallón (jltal...@adv-solutions.net) wrote: > > On 12/04/2014 07:35 AM, Amit Kapila wrote: > > >The number of worker backends that can be used for > > >parallel seq scan can be configured by using a new GUC > > >parallel_seqscan_degree, the default value of which is zero > > >and it means parallel seq scan will not be considered unless > > >user configures this value. > > > > The number of parallel workers should be capped (of course!) at the > > maximum amount of "processors" (cores/vCores, threads/hyperthreads) > > available. > > > > More over, when load goes up, the relative cost of parallel working > > should go up as well. > > Something like: > > p = number of cores > > l = 1min-load > > > > additional_cost = tuple estimate * cpu_tuple_cost * (l+1)/(c-1) > > > > (for c>1, of course) > > While I agree in general that we'll need to come up with appropriate > acceptance criteria, etc, I don't think we want to complicate this patch > with that initially. > >A SUSET GUC which caps the parallel GUC would be > enough for an initial implementation, imv. >
This is exactly what I have done in patch. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
