"Shridhar Daithankar" <shridhar_daithankar@persistent.co.in> writes:
> On 11 Dec 2002 at 12:52, Nicolai Tufar wrote:
>> OS caching is generally considered a waste of resource in databases.
>> Try to allocate as much as possible to shared buffers and set OS caching
>> to minimum.
> That is an exactly opposite of the truth. Leave as much for OS cache and do
> minimum use of shared buffers.
There are varying opinions about that. Some say "push PG's
shared-buffers setting as high as you can make it". Some say "use a
conservatively small shared-buffers setting and expect the kernel to use
the rest of physical memory as kernel disk buffers". But both camps
agree that a shared-buffers setting near 50% of physical RAM will suck:
then any given page of database is likely to get cached *both* in PG's
buffers and in kernel buffers. That behavior can't win by any measure.
regards, tom lane