Message-ID: <4E9461A0.3070008@2ndQuadrant.com>
Date: Tue, 11 Oct 2011 11:32:48 -0400
From: Greg Smith <greg@2ndQuadrant.com>
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To: Leonardo Francalanci <m_lists@yahoo.it>
CC: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Adding more memory = hugh cpu load
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On 10/11/2011 04:57 AM, Leonardo Francalanci wrote:
> In fact, shouldn't those things be explained in the "WAL 
> Configuration" section
> of the manual? It looks as important as configuring Postgresql itself...
> And: that applies to Linux. What about other OS, such as Solaris and FreeBSD?
>    

There's at least 10 pages of stuff about this floating around my book, 
including notes on the similar Solaris and FreeBSD parameters to tune.

As for why that's not in the manual instead, two reasons.  The 
PostgreSQL manual doesn't get too deep into things like operating system 
adjustments for performance.  It's big enough without that, and any 
information that would be added is likely to get out of sync with new OS 
releases.  This project doesn't want to take on the job of documenting 
every twist there.  My book is less than a year old, and there's already 
some material on this topic that's turning obsolete due to Linux kernel 
changes.  The PostgreSQL manual is shooting to still be relevant for 
much longer than that.

Second, making an addition to the manual is the hardest possible way to 
document things.  The docbook toolchain used is picky and fragile to 
malformed additions.  And you can't get anything added there without 
passing through a series of people who will offer feedback of some sort; 
usually valuable, but still time consuming to process.  Things need to 
asked quite frequently before it's worth the trouble.  I did a few blog 
entries and mailing list posts about this earlier this year, and that 
was as much documentation as I could justify at the time.  If there's a 
user-visible behavior changes here, that's the point where an update to 
the manual would be in order.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us