On Wed, Oct 9, 2013 at 12:25:49PM -0400, Bruce Momjian wrote: > > I'm not saying don't do it, but I think we need to be quite > > conservative about it. A reasonable default might be (shared_buffers > > / (n * max_connections)) FSVO n, but I'm not sure what n should be. > > Instinct says something like 4, but I have no data to back that up. > > I am fine with '4' --- worked as an effective_cache_size multipler. ;-) > I think we should try to hit the existing defaults, which would mean we > would use this computation: > > (shared_buffers / 4) / max_connections + 768k / BUFSZ > > This would give us for a default 128MB shared buffers and 100 > max_connections: > > (16384 / 4) / 100 + (768 * 1024) / 8192 > > which gives us 136, and that is 136 * 8192 or 1088k, close to 1MB. > > For 10x shared buffers, 163840, it gives a work_mem of 4040k, rather > than the 10M I was computing in the original patch. > > How is that?
In summary, that would be 615MB for shared_buffers of 2GB, assuming one work_mem per session, and assuming you are running the maximum number of sessions, which you would not normally do. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
