Sean,

> > That's exactly my point.  We cannot provide enough documentation in
> > the CONF file without septupling its length.  IF we remove all
> > commentary, and instead provide a pointer to the documentation, more
> > DBAs will read it.
>
> Which I don't think would happen and why I think the terse bits that
> are included are worth while.  :)

Depressingly enough, you are probably correct, unless we assemble a more 
user-friendly "getting started" guide.

> *) concurrent disk activity
>
> A disk/database activity metric is different than the cost of a seek
> on the platters.  :) Because PostgreSQL doesn't currently support such
> a disk concurrency metric doesn't mean that its definition should get
> rolled into a different number in an attempt to accommodate for a lack
> thereof.

I was talking about concurrent activity by *other* applications.  For example, 
if a DBA has a java app that is accessing XML on the same array as postgres 
500 times/minute, then you'd need to adjust random_page_cost upwards to allow 
for the resource contest.

> An "ideal" value isn't obtained via guess and check.  Checking is only
> the verification of some calculable set of settings....though right now
> those calculated settings are guessed, unfortunately.

> Works for me, though a benchmark will be less valuable than adding a
> disk concurrency stat, improving data trend/distribution analysis, and
> using numbers that are concrete and obtainable through the OS kernel
> API or an admin manually plunking numbers in.  I'm still recovering
> from my move from Cali to WA so with any luck, I'll be settled in by
> then.

The idea is that for a lot of statistics, we're only going to be able to 
obtain valid numbers if you have something constant to check them against.

Talk to you later this month!

-- 
Josh Berkus
Aglio Database Solutions
San Francisco

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