2010/1/29 Richard Neill <rn214@cam.ac.uk>:
>
>
> **Rod MacNeil wrote:
>>
>> Hi All,
>>
>> I have a server running CentOS5 with 6gb of memory that will run postgres
>> 8.3 exclusively.
>> I would like to allocate 4gb of the memory to shared buffers for postgres.
>
> It might be worth pausing at this point:
>
> The various postgresql tuning guides usually suggest that on a dedicated
> system, you should give postgres about 1/4 of the RAM for shared buffers,
> while telling it that the effective_cache_size = 1/2 RAM.
>
> Postgres will make good use of the OS cache as a file-cache - the
> "effective_cache_size" setting is advisory to postgres that it can expect
> about this much data to be in RAM.
AFAIK effective_cache_size is estimation of OS Page Cache + Estimated
Cache in shared_buffers.
>
> Also, If you are setting up a new system, it's probably worth going for
> 8.4.2. Postgres is relatively easy to build from source.
>
> HTH,
>
> Richard
>
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Cédric Villemain