Message-ID: <541CC338.5090700@catalyst.net.nz>
Date: Sat, 20 Sep 2014 11:58:48 +1200
From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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To: "Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>
CC: Merlin Moncure <mmoncure@gmail.com>,
 postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: postgres 9.3 vs. 9.4
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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).

Regards

Mark

[1] In the light of my previous test of (essentially) your config + 
numerous other folk have been benchmarking 9.4.


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