From: Andrew Sullivan <ajs@commandprompt.com>
To: pgsql-performance@postgresql.org
Subject: Re: Which hardware ?
Date: Tue, 17 Jun 2008 10:25:02 -0400
Message-ID: <20080617142501.GG68434@commandprompt.com> (raw)
In-Reply-To: <g38epm$2pl4$1@news.hub.org>
References: <g38epm$2pl4$1@news.hub.org>
On Tue, Jun 17, 2008 at 03:38:59PM +0200, Lionel wrote:
> Hi,
>
> I need to install a 8.3 database and was wondering which hardware would be
> sufficient to have good performances (less than 30s for² slowest select).
> Statements will mainly do sums on the main table, grouped by whatever column
> of the database (3-5 joined tables, or join on join), with some criterions
> that may vary, lots of "joined varchar in ('a','b',...,'z')".
> It's almost impossible to predict what users will do via the webapplication
> that queries this database: almost all select, join, group by, where...
> possibilities are available.
I'm not sure that I have any specific recommendation to make in the
face of such sweeping requirements. But I'd say you need to make I/O
cheap, which means piles of memory and extremely fast disk
subsystems.
Also, there's another important question (which never gets asked in
these discussions), which is, "How much is the performance worth to
you?" If the last 10% of users get something longer than 30s, but
less than 40s, and they will pay no more to get the extra 10s response
time, then it's worth nothing to you, and you shouldn't fix it.
> Up to 4 simultaneous users.
You won't need lots of processer, then.
> I'm planning to host it on a quad xeon 2.66Ghz with 8Go of DDR2, and a dual
> (RAID1) SATA2 750Go HD.
> Perharps with another HD for indexes.
How big's the database? If you can have enough memory to hold the
whole thing, including all indexes, in memory, that's what you want.
Apart from that, "dual SATA2" is probably underpowered. But. . .
> Which OS would you use ? (knowing that there will be a JDK 1.6 installed
> too)
. . .I think this is the real mistake. Get a separate database box.
It's approximately impossible to tune a box correctly for both your
application and your database, in my experience.
A
--
Andrew Sullivan
ajs@commandprompt.com
+1 503 667 4564 x104
http://www.commandprompt.com/
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To: pgsql-performance@postgresql.org
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Subject: Re: Which hardware ?
In-Reply-To: <20080617142501.GG68434@commandprompt.com>
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