Re: postgres 9.3 vs. 9.4 - Mailing list pgsql-performance

Hi Merlin,

you are right, in 9.4 the debug_assertions are on:

# /etc/init.d/postgresql-9.4 start
Starting postgresql-9.4 service:                           [  OK  ]
# psql -U postgres
psql (9.4beta2)
Type "help" for help.

postgres=# select name,setting from pg_settings where name='debug_assertions';
       name       | setting
------------------+---------
 debug_assertions | on
(1 row)

postgres=# \q
# /etc/init.d/postgresql-9.4 stop
Stopping postgresql-9.4 service:                           [  OK  ]
# /etc/init.d/postgresql-9.3 start
Starting postgresql-9.3 service:                           [  OK  ]
# psql -U postgres
psql (9.4beta2, server 9.3.5)
Type "help" for help.

postgres=# select name,setting from pg_settings where name='debug_assertions';
       name       | setting
------------------+---------
 debug_assertions | off
(1 row)

postgres=# \q
#


The rpms are coming from Postgres official repo:

http://yum.postgresql.org/9.4/redhat/rhel-$releasever-$basearch


Tigran.


----- Original Message -----
> From: "Merlin Moncure" <mmoncure@gmail.com>
> To: "Mark Kirkwood" <mark.kirkwood@catalyst.net.nz>
> Cc: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>, "postgres performance list" <pgsql-performance@postgresql.org>
> Sent: Monday, September 22, 2014 3:37:50 PM
> Subject: Re: [PERFORM] postgres 9.3 vs. 9.4
>
> On Fri, Sep 19, 2014 at 6:58 PM, Mark Kirkwood
> <mark.kirkwood@catalyst.net.nz> wrote:
> > On 19/09/14 19:24, Mkrtchyan, Tigran wrote:
> >>
> >>
> >>
> >> ----- Original Message -----
> >>>
> >>> From: "Mark Kirkwood" <mark.kirkwood@catalyst.net.nz>
> >>> To: "Tigran Mkrtchyan" <tigran.mkrtchyan@desy.de>
> >>> Cc: "Merlin Moncure" <mmoncure@gmail.com>, "postgres performance list"
> >>> <pgsql-performance@postgresql.org>
> >>> Sent: Friday, September 19, 2014 8:26:27 AM
> >>> Subject: Re: [PERFORM] postgres 9.3 vs. 9.4
> >>>
> >>> On 19/09/14 17:53, Mkrtchyan, Tigran wrote:
> >>>>
> >>>>
> >>>>
> >>>> ----- Original Message -----
> >>>>>
> >>>>> From: "Mark Kirkwood" <mark.kirkwood@catalyst.net.nz>
> >>>
> >>>
> >>>>> Further to the confusion, here's my 9.3 vs 9.4 on two M550 (one for 9.3
> >>>>> one for 9.4), see below for results.
> >>>>>
> >>>>> I'm running xfs on them with trim/discard enabled:
> >>>>>
> >>>>> $ mount|grep pg
> >>>>> /dev/sdd4 on /mnt/pg94 type xfs (rw,discard)
> >>>>> /dev/sdc4 on /mnt/pg93 type xfs (rw,discard)
> >>>>>
> >>>>>
> >>>>> I'm *not* seeing any significant difference between 9.3 and 9.4, and
> >>>>> the
> >>>>> numbers are both about 2x your best number, which is food for thought
> >>>>> (those P320's should toast my M550 for write performance...).
> >>>>
> >>>>
> >>>> cool! any details on OS and other options? I still get the same numbers
> >>>> as before.
> >>>>
> >>>
> >>> Sorry, Ubuntu 14.04 on a single socket i7 3.4 Ghz, 16G (i.e my
> >>> workstation).
> >>>
> >>> I saw the suggestion that Didier made to run 9.3 on the SSD that you
> >>> were using for 9.4, and see if it suddenly goes slow - then we'd know
> >>> it's something about the disk (or filesystem/mount options). Can you
> >>> test this?
> >>
> >>
> >>
> >> swapping the disks did not change the results.
> >>
> >>
> >
> > Do you mean that 9.3 was still faster using the disk that 9.4 had used? If
> > so that strongly suggests that there is something you have configured
> > differently in the 9.4 installation [1]. Not wanting to sound mean - but it
> > is really easy to accidentally connect to the wrong instance when there are
> > two on the same box (ahem, yes , done it myself). So perhaps another look
> > at
> > the 9.4 vs 9.3 setup (or even posti the config files postgresql.conf +
> > postgresql.auto.conf for 9.4 here).
>
> Huh.  Where did the 9.4 build come from?  I wonder if there are some
> debugging options set.   Can you check 9.4 pg_settings for value
> of"debug_assertions"?   If it's set true, you might want to consider
> hand compiling postgres until 9.4 is released...
>
> merlin
>