Re: postgres 9.3 vs. 9.4

----- Original Message -----
> From: "Jeff Janes" <jeff(dot)janes(at)gmail(dot)com>
> To: "Tigran Mkrtchyan" <tigran(dot)mkrtchyan(at)desy(dot)de>
> Cc: pgsql-performance(at)postgresql(dot)org
> Sent: Thursday, September 18, 2014 4:56:22 PM
> Subject: Re: [PERFORM] postgres 9.3 vs. 9.4
>
> On Thu, Sep 18, 2014 at 2:58 AM, Mkrtchyan, Tigran <tigran(dot)mkrtchyan(at)desy(dot)de
> > wrote:
>
> >
> >
> > Hi Folk,
> >
> > I am trying to investigate some performance issues which we have with
> > postgres
> > (a different topic by itself) and tried postgres.9.4beta2, with a hope
> > that it
> > perform better.
> >
> > Turned out that 9.4 is 2x slower than 9.3.5 on the same hardware.
> >
> > Some technical details:
> >
> > Host: rhel 6.5 2.6.32-431.23.3.el6.x86_64
> > 256 GB RAM, 40 cores, Intel(R) Xeon(R) CPU E5-2660 v2 @ 2.20GHz
> > 2x160GB PCIe SSD DELL_P320h-MTFDGAL175SAH ( on one 9.3, on an other one
> > 9.4 )
> >
>
> Why are the versions segregated that way? Are you sure they are configured
> identically?

es, they are configured identically
>
>
> >
> > postgres tweaks:
> >
> >
> > default_statistics_target = 100
> > wal_writer_delay = 10s
> > vacuum_cost_delay = 50
> > synchronous_commit = off
> >
>
> Are you sure that synchronous_commit is actually off on the 9.4 instance?

yes, synchronous_commit is off.

>
> 9.3.5:
> >
> > # /usr/pgsql-9.3/bin/pgbench -r -j 1 -c 1 -T 60
> >
>
> ...
>
>
> > 0.035940 END;
> >
> >
> > 9.4beta2:
> >
> ...
>
> > 0.957854 END;
> >
>
> Looks like IO.

Postgres internal IO? May be. We get 600MB/s on this SSDs.

Tigran.

>
> Cheers,
>
> Jeff
>