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From: Heikki Linnakangas <heikki@enterprisedb.com>
To: amrit angsusingh <amritspr@gmail.com>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: Optimization postgresql 8.1.4 FC 6 X64 ?
Date: Sat, 24 Mar 2007 10:44:47 +0000
Message-ID: <4605011F.1040803@enterprisedb.com> (raw)
In-Reply-To: <3af7f950703232315g19e5d6d0o9ab54e489b8082c6@mail.gmail.com>
References: <3af7f950703232315g19e5d6d0o9ab54e489b8082c6@mail.gmail.com>

amrit angsusingh wrote:
> I try to change my database server from the older one ie. 2Cpu Xeon 2.4 32
> bit 4Gb SDram Hdd SCSI RAID 5 and FC 3 ix86 with 7..4.7 PG to the newer one
> with 2CPU Xeon 3.0 64 Bit 4Gb DDRram SCSI Raid5 and FC6 X64 PG 8.14 and try
> to use  rather the same parameter from the previous postgresql.conf :-
> ...
> I use pgbench to test the speed of my older database server and the result
> is
> 
> bash-3.00$ pgbench  test -t 20 -c 30 -s 50
> ...

-t 20 is not enough to give repeatable results. Try something like -t 1000.

The speed of pgbench in that configuration (scaling factor 50, fsync 
enabled) is limited by the speed you can fsync the WAL. There isn't much 
you can do in postgresql.conf for that. If you get similar results with 
higher -t setting, it may be because your new RAID and drives have 
slightly higher latency.

You're better off testing with real queries with your real database.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com



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