Why is my name on a mail from Tom Lane ? Really, he knows a *lot* more than I and should get due credit.
Seriously, is this the peformance remailer mangling something ? Greg Williamson (the real one) -----Original Message----- From: Gregory S. Williamson Sent: Sun 6/6/2004 10:46 PM To: Sean Shanny Cc: [EMAIL PROTECTED] Subject: Re: [PERFORM] General performance questions about postgres on Apple In-reply-to: <[EMAIL PROTECTED]> References: <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> Comments: In-reply-to Sean Shanny <[EMAIL PROTECTED]>message dated "Sun, 22 Feb 2004 21:48:54 -0500" Date: Sun, 22 Feb 2004 22:24:29 -0500 Message-ID: <[EMAIL PROTECTED]> From: Tom Lane <[EMAIL PROTECTED]> X-Virus-Scanned: by amavisd-new at postgresql.org X-Mailing-List: pgsql-performance Precedence: bulk Sender: [EMAIL PROTECTED] X-imss-version: 2.5 X-imss-result: Passed X-imss-scores: Clean:99.90000 C:21 M:2 S:5 R:5 X-imss-settings: Baseline:2 C:2 M:2 S:2 R:2 (0.1500 0.3000) Return-Path: [EMAIL PROTECTED] X-OriginalArrivalTime: 07 Jun 2004 05:27:21.0994 (UTC) FILETIME=[1BC0EEA0:01C44C50] Sean Shanny <[EMAIL PROTECTED]> writes: > We have the following setting for random page cost: > random_page_cost = 1 # units are one sequential page fetch cost > Any suggestions on what to bump it up to? Well, the default setting is 4 ... what measurements prompted you to reduce it to 1? The particular example you showed suggested that the true value on your setup might be 10 or more. Now I would definitely not suggest that you settle on any particular value based on only one test case. You need to try to determine an appropriate average value, bearing in mind that there's likely to be lots of noise in any particular measurement. But in general, setting random_page_cost to 1 is only reasonable when you are dealing with a fully-cached-in-RAM database, which yours isn't. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster