Hi On Thu, Apr 2, 2015 at 3:52 PM, Pietro Pugni <pietro.pugni@xxxxxxxxx> wrote: > > I’ve searched just now what a collation is because I’ve never explicitly > used one before, so I think it uses the default one. > > > What's the output of free and sysctl -a | grep vm.zone_reclaim_mode > > Search the mailing list for zone_reclaim_mode there's some tips. > > vm.zone_reclaim_mode = 0 In my understanding it's the rigth value there's also huge page /sys/kernel/mm/transparent_hugepage/enabled can you try to disable it? Also test on the dell: select tmp.cf, tmp.dt from grep_studi.tmp; and select tmp.cf, tmp.dt from grep_studi.tmp order by tmp.cf; in Query B_2 the sort is 9 time slower on the dell, you have to find why... > > For testing you can also use the mac mini config with the dell, at > least it should give you the same plan. > With your example disks don't seem to matter, it's all in memory. > T420 with optimal postgresql.conf > Query B_1 [55999.649 ms + 0.639 ms] http://explain.depesz.com/s/LbM > Query B_2 [95664.832 ms + 0.523 ms] http://explain.depesz.com/s/v06 > > > T420 with MacMini postgresql.conf > Query B_1 [51280.208ms + 0.699ms] http://explain.depesz.com/s/wlb > Query B_2 [177278.205ms + 0.428ms] http://explain.depesz.com/s/rzr > 32 GB for buffers is too high for the queries in your test but it doesn't matter. > MacMini > Query B_1 [56315.614 ms] http://explain.depesz.com/s/uZTx > Query B_2 [44890.813 ms] http://explain.depesz.com/s/y7Dk > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
