Hi
On Thu, Apr 2, 2015 at 3:52 PM, Pietro Pugni <pietro.pugni@gmail.com> 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
>
