Re: Which hardware ?

From: Greg Smith <gsmith(at)gregsmith(dot)com>
To: Andrew Sullivan <ajs(at)commandprompt(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Which hardware ?
Date: 2008-06-17 16:32:10
Message-ID: Pine.GSO.4.64.0806171219410.10502@westnet.com
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On Tue, 17 Jun 2008, Andrew Sullivan wrote:

> A running JVM is necessarily going to use some memory, and that is
> memory use that you won't be able to factor out properly when developing
> models of your database system performance.

Now you've wandered into pure FUD. Tuning maximum memory usage on a Java
app so you can model it is straightforward (albeit a little confusing at
first), and in most cases you can just sample it periodically to get a
good enough estimate for database tuning purposes. JVMs let you adjust
maximum memory use with -Xmx , and if anything the bigger problem I run
into is that using too much memory hits that limit and crashes Java long
before it becomes a hazard to the database.

This is a system with 8GB of RAM here; having some Tomcat instances
co-existing with the database when there's that much room to work is not
that hard.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD

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