Hi, On 2013-12-03 10:44:15 -0800, Josh Berkus wrote: > I don't know where we'll get the resources to implement our own storage, > but it's looking like we don't have a choice.
As long as our storage layer is a s suboptimal as it is today, I think it's a purely detractory to primarily blame the kernel. We * cannot deal with large shared_buffers, the dirty-buffer scanning is far to expensive. The amount of memory required for locks is pretty big, and every backend carries around a pretty huge private array for the buffer pins. * do not have scalability in pretty damn central datastructures like buffer mapping. * Our background eviction mechanism doesn't do anything in lots of workloads but increase contention on important data structures. * Due to the missing efficient eviction, we synchronously write out data when acquiring a victim buffer most of the time. That's already bad if you have a kernel buffering your writes, but if you don't... * Due to the frequency of buffer pins in almost all workloads, our tracking of the importance of individual buffers is far, far too volatile. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers