Re: Postgres not using array

From: Mark Mielke <mark(at)mark(dot)mielke(dot)cc>
To: André Volpato <andre(dot)volpato(at)ecomtecnologia(dot)com(dot)br>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Postgres not using array
Date: 2008-08-21 14:16:40
Message-ID: 48AD78C8.80500@mark.mielke.cc
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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(at)mielke(dot)cc>

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