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.
> Not directly (I haven't had the time to read the code yet), but I'm
> thinking about the ability to simply *replace* executor methods from
> an extension.
You probably want to look at the CustomScan thread+patch directly then..
Thanks,
Stephen
signature.asc
Description: Digital signature
