Yes, Claudio. You got it. But Rob seems to have already answered the confusion between 32 and 64 bits for effective_cache_size. Actually I am creating generic configuration based on physical memory. So I wanna be conservative about effective_cache_size. That's why I'm following postgres tuning website instructions. If it says it is conservative, that's good for me.
On Mon, Mar 18, 2013 at 3:51 PM, Claudio Freire <klaussfre...@gmail.com>wrote: > On Mon, Mar 18, 2013 at 3:47 PM, Kevin Grittner <kgri...@ymail.com> wrote: > > Rodrigo Barboza <rodrigombu...@gmail.com> wrote: > > > >> So setting this as half of ram, as suggested in postgres tuning > >> webpage should be safe? > > > > Half of RAM is likely to be a very bad setting for any work load. > > It will tend to result in the highest possible number of pages > > duplicated in PostgreSQL and OS caches, reducing the cache hit > > ratio. More commonly given advice is to start at 25% of RAM, > > limited to 2GB on Windows or 32-bit systems or 8GB otherwise. Try > > incremental adjustments from that point using your actual workload > > on you actual hardware to find the "sweet spot". Some DW > > environments report better performance assigning over 50% of RAM to > > shared_buffers; OLTP loads often need to reduce this to prevent > > periodic episodes of high latency. > > > He's asking about effective_cache_size. You seem to be talking about > shared_buffers. > > Real question behind this all, is whether the e_c_s GUC is 32-bit on > 32-bit systems. Because if so, it ought to be limited too. If not... > not. >
