Re: effective_cache_size on 32-bits postgres

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.

--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company