Message-ID: <48484380.1010504@cheapcomplexdevices.com>
Date: Thu, 05 Jun 2008 12:50:24 -0700
From: Ron Mayer <rm_pg@cheapcomplexdevices.com>
User-Agent: Mozilla-Thunderbird 2.0.0.14 (X11/20080509)
MIME-Version: 1.0
To: Tom Lane <tgl@sss.pgh.pa.us>
CC: Andrew Dunstan <andrew@dunslane.net>, Greg Smith <gsmith@gregsmith.com>,
	Andreas Pflug <pgadmin@pse-consulting.de>,
	"Decibel!" <decibel@decibel.org>,
	Peter Eisentraut <peter_e@gmx.net>, pgsql-hackers@postgresql.org,
	Josh Berkus <josh@agliodbs.com>
Subject: Re: Overhauling GUCS
References: <48409D1E.3070208@agliodbs.com>
	<200806010032.53337.peter_e@gmx.net>
	<Pine.GSO.4.64.0806020452220.26912@westnet.com>
	<17932.1212415926@sss.pgh.pa.us>
	<20080604131810.GH65238@decibel.org>
	<4846A483.8000001@pse-consulting.de>
	<Pine.GSO.4.64.0806041045520.2258@westnet.com>
	<29525.1212613052@sss.pgh.pa.us>
	<48472E47.7030701@dunslane.net> <7473.1212625397@sss.pgh.pa.us>
In-Reply-To: <7473.1212625397@sss.pgh.pa.us>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Tom Lane wrote:
> How far could we get with the answers to just three questions:
> 
> * How many concurrent queries do you expect to have?
> * How much RAM space are you willing to let Postgres use?
> * How much "overhead" disk space are you willing to let Postgres use?

+1 to this approach - these are the kinds of questions that
make sense to me when first setting up a new installation.
They sound useful for both large servers and tiny (salesguy
laptop for demos) installations.

> If those aren't enough questions, what else must we ask? 

* Perhaps something to guess FSM settings?  I think FSM is
   tunable I most often get wrong with more painful
   consequences (bloat) than other tunables.
   My approach is to have cron run database-wide vacuums
   even on systems with autovacuum just to see the log
   messages about FSM.

* Something to tune vacuum delay?  Perhaps:
   How much I/O bandwidth can be dedicated to Postgres
   background activities?