On Wed, 2008-05-28 at 16:59 -0700, Josh Berkus wrote: > Folks, > shared_buffers: according to witnesses, Greg Smith presented at East that > based on PostgreSQL's buffer algorithms, buffers above 2GB would not > really receive significant use. However, Jignesh Shah has tested that on > workloads with large numbers of connections, allocating up to 10GB > improves performance. I have seen multiple production systems where upping the buffers up to 6-8GB helps. What I don't know, and what I am guessing Greg is referring to is if it helps as much as say upping to 2GB. E.g; the scale of performance increase goes down while the actual performance goes up (like adding more CPUs). > > sort_mem: My tests with 8.2 and DBT3 seemed to show that, due to > limitations of our tape sort algorithm, allocating over 2GB for a single > sort had no benefit. However, Magnus and others have claimed otherwise. > Has this improved in 8.3? I have never see work_mem (there is no sort_mem Josh) do any good above 1GB. Of course, I would never willingly use that much work_mem unless there was a really good reason that involved a guarantee of not calling me at 3:00am. > > So, can we have some test evidence here? And workload descriptions? > Its all, tune now buddy :P Sinceerely, Joshua D. Drake
