On Thu, Sep 5, 2013 at 09:02:27PM -0700, Josh Berkus wrote: > On 09/05/2013 03:30 PM, Merlin Moncure wrote: > > >> Standard advice we've given in the past is 25% shared buffers, 75% > >> effective_cache_size. Which would make EFS *3X* shared_buffers, not 4X. > >> Maybe we're changing the conventional calculation, but I thought I'd > >> point that out. > > > > This was debated upthread. > > Actually, no, it wasn't. Tom threw out a suggestion that we use 4X for > historical reasons. That's all, there was no discussion. > > So, my point stands: our historical advice has been to set EFS to 75% of > RAM. Maybe we're changing that advice, but if so, let's change it. > Otherwise 3X makes more sense.
So, what do we want the effective_cache_size default to be? 3x or 4x? We clearly state: If you have a dedicated database server with 1GB or more of RAM, a reasonable starting value for shared_buffers is 25% of the memory in your system. There are some workloads where even If we make the default 4x, that means that people using the above suggestion would be setting their effective_cache_size to 100% of RAM? If we go with 4x, which I believe was the majority opinion, what shall we answer to someone who asks about this contradiction? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers