Message-ID: <48AD78C8.80500@mark.mielke.cc>
Date: Thu, 21 Aug 2008 10:16:40 -0400
From: Mark Mielke <mark@mark.mielke.cc>
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To: =?ISO-8859-1?Q?Andr=E9_Volpato?=
 <andre.volpato@ecomtecnologia.com.br>
CC: pgsql-performance@postgresql.org
Subject: Re: Postgres not using array
References: <48AC8292.5000708@ecomtecnologia.com.br>
	<48AD735D.6040403@ecomtecnologia.com.br>
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André Volpato wrote:
> In practice, I have noticed that dual 1.8 is worse than single 3.0. We 
> have another server wich
> is a Pentium D 3.0 GHz, that runs faster.
> ...
> Postgres read the array in less than 1 sec, and the other 10s he takes 
> 100% of CPU usage,
> wich is, in this case, one of the two cores at 1.8GHz.
>
> I am a bit confused about what CPU is best for Postgres. Our apps is 
> mostly read, with
> a few connections and heavy queryes.
> Does it worth a multi-core ?

How are you doing your benchmarking? If you have two or more queries 
running at the same time, I would expect the 1.8 Ghz x 2 to be 
significant and possibly out-perform the 3.0 Ghz x 1. If you usually 
only have one query running at the same time, I expect the 3.0 Ghz x 1 
to always win. PostgreSQL isn't good at splitting the load from a single 
client across multiple CPU cores.

Cheers,
mark

-- 
Mark Mielke <mark@mielke.cc>