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