Re: effective_cache_size on 32-bits postgres

2013/3/18 Kevin Grittner <kgrittn@ymail.com>:
> Rodrigo Barboza <rodrigombufrj@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.

you are speaking about shared_buffers now.

Pavel

>
> --
> Kevin Grittner
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