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

From Jeff Janes
Subject Re: postgres 9.3 vs. 9.4
Date
Msg-id CAMkU=1zhg1pQrh7BfafTQUezbNkgy=s778UyssmNKX6xKDJ3sA@mail.gmail.com
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In response to postgres 9.3 vs. 9.4  ("Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>)
Responses Re: postgres 9.3 vs. 9.4  ("Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>)
List pgsql-performance
On Thu, Sep 18, 2014 at 2:58 AM, Mkrtchyan, Tigran <tigran.mkrtchyan@desy.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?  
 

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?

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.

Cheers,

Jeff

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