On Thu, Apr 22, 2021 at 2:55 PM Luca Ferrari <fluca1978@xxxxxxxxx> wrote: > > On Thu, Apr 22, 2021 at 9:52 PM Bruce Momjian <bruce@xxxxxxxxxx> wrote: > > > > On Thu, Apr 22, 2021 at 09:45:15PM +0200, Luca Ferrari wrote: > > > Hi all, > > > I'm unable to find (apparently) a way to find out a possible value to > > > start with for effective_io_concurrency. > > > I suspect that benchmarking, e.g., using bonnie++ or sysbench and > > > testing with different values of concurrency could help to determine > > > the max number of concurrent request, (tps, lower latency, ecc.). > > > Is thjs correct or is there another suggested way? > > > > I recommend 256 for SSDs or other RAM-like fsync systems, and maybe > > maybe 16 for magnetic. > > > Thanks Bruce, this is a very good starting point. > But is there a rationale about those numbers? I mean, if I change the > storage system, how should I set a correct number? See thread, https://postgrespro.com/list/thread-id/2069516 The setting only impacts certain scan operations, it's not a gamechanger. merlin
