Re: proposal: Set effective_cache_size to greater of .conf value, shared_buffers

On Tue, May 6, 2014 at 10:20 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 6 May 2014 23:47, Josh Berkus <josh@agliodbs.com> wrote:
>
>> If you're going to make
>> an argument in favor of different tuning advice, then do it based on
>> something in which you actually believe, based on hard evidence.
>
> The proposed default setting of 4x shared_buffers is unprincipled
> *and* lacks hard evidence from you and everybody else.

+1. In my view, we probably should have set it to a much higher
absolute default value. The main problem with setting it to any
multiple of shared_buffers that I can see is that shared_buffers is a
very poor proxy for what effective_cache_size is supposed to
represent. In general, the folk wisdom around sizing shared_buffers
has past its sell-by date.

-- 
Peter Geoghegan