Re: effective_cache_size on 32-bits postgres

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 <klaussfreire(at)gmail(dot)com>wrote:

> On Mon, Mar 18, 2013 at 3:47 PM, Kevin Grittner <kgrittn(at)ymail(dot)com> wrote:
> > Rodrigo Barboza <rodrigombufrj(at)gmail(dot)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.
>