On 05/07/2014 11:52 AM, Peter Geoghegan wrote: > On Wed, May 7, 2014 at 11:40 AM, Josh Berkus <j...@agliodbs.com> wrote: >> So, as one of several people who put literally hundreds of hours into >> the original benchmarking which established the sizing recommendations >> for shared_buffers (and other settings), I find the phrase "folk wisdom" >> personally offensive. So, can we stop with this? > > I have also put a lot of time into benchmarking. No personal offence > was intended, and I'm glad that we have some advice to give to users, > but the fact of the matter is that current *official* recommendations > are very vague.
Well, they should be vague; the only hard data we have is rather out-of-date (I think 8.2 was our last set of tests). If we gave users specific, detailed recommendations, we'd be misleading them. For that matter, our advice on shared_buffers ... and our design for it ... is going to need to change radically soon, since Linux is getting an ARC with a frequency cache as well as a recency cache, and FreeBSD and OpenSolaris already have them. FWIW, if someone could fund me for a month, I'd be happy to create a benchmarking setup where we could test these kinds of things; I have pretty clear ideas how to build one. I imagine some of our other consultants could make the same offer. However, it's too much work for anyone to get done "in their spare time". -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
