Re: Same query doing slow then quick - Mailing list pgsql-performance

From FFW_Rude
Subject Re: Same query doing slow then quick
Date
Msg-id SNT111-W2025F9BE2B94A56FE1CE13E19C0@phx.gbl
Whole thread Raw
In response to Re: Same query doing slow then quick  (Nikolay Ulyanitsky <lystor@gmail.com>)
Responses Re: Same query doing slow then quick  (Nikolay Ulyanitsky <lystor@gmail.com>)
List pgsql-performance
Hi,

root@testBI:/etc/postgresql/9.1/main# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   892 MB in  2.01 seconds = 444.42 MB/sec
 Timing buffered disk reads: 190 MB in  3.02 seconds =  62.90 MB/sec

Is fsync off by default ? I have
#fsync = on (so it's off right ?).

pgbench is not found on my server. Do i have to apt-get install pgbench ?

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Date: Wed, 26 Sep 2012 08:34:06 -0700
From: [hidden email]
To: [hidden email]
Subject: Re: Same query doing slow then quick

Hi, FFW_Rude

1. Benchmark the device with your PostgreSQL DB:

# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   6604 MB in  2.00 seconds = 3303.03 MB/sec
 Timing buffered disk reads: 1316 MB in  3.00 seconds = 438.18 MB/sec


2. Benchmark your PostgreSQL with pgbench:

Set "fsync = off" on /var/lib/pgsql/data/postgresql.conf
# /etc/init.d/postgresql restart

# su - postgres
$ psql
# create database pgbench;
# \q
# pgbench -i pgbench && pgbench -c 10 -t 10000 pgbench
tps = 5670.635648 (including connections establishing)
tps = 5673.630345 (excluding connections establishing)[/code]

Set "fsync = on" on /var/lib/pgsql/data/postgresql.conf
# /etc/init.d/postgresql restart


--
With best regards,
Nikolay



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