On Tue, 19 Jun 2007, Josh Berkus wrote:
> I don't think the "mostly reads / mostly writes" question covers anything,
> nor is it likely to produce accurate answers. Instead, we need to ask the
> users to characterize what type of application they are running:
> T1) Please characterize the general type of workload you will be running on
> this database. Choose one of the following four...
We've hashed through this area before, but for Lance's benefit I'll
reiterate my dissenting position on this subject. If you're building a
"tool for dummies", my opinion is that you shouldn't ask any of this
information. I think there's an enormous benefit to providing something
that takes basic sizing information and gives conservative guidelines
based on that--as you say, "safe, middle-of-the-road values"--that are
still way, way more useful than the default values. The risk in trying to
make a complicated tool that satisfies all the users Josh is aiming his
more sophisticated effort at is that you'll lose the newbies.
Scan the archives of this mailing list for a bit. If you look at what
people discover they've being nailed by, it's rarely because they need to
optimize something like random_page_cost. It's usually because they have
a brutally wrong value for one of the memory or vacuum parameters that are
very easy to provide reasonable suggestions for without needing a lot of
information about the server.
I wouldn't even bother asking how many CPUs somebody has for what Lance is
building. The kind of optimizations you'd do based on that are just too
complicated to expect a tool to get them right and still be accessible to
a novice.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
