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@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD
