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Re: Limited Shared Buffer Problem

From: "Ing (dot) Marcos Luís Ortíz Valmaseda" <mlortiz(at)uci(dot)cu>
To: Richard Neill <rn214(at)cam(dot)ac(dot)uk>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Limited Shared Buffer Problem
Date: 2010-01-29 18:24:12
Message-ID: 4B6327CC.7070909@uci.cu (view raw or flat)
Thread:
Lists: pgsql-performance
Richard Neill escribió:
>
>
> **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.
>
> 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
>
All these values has to be combined with the others: shared_buffers, 
work_mem,etc.
My recommendation is to go down a little the shmmax and the 
shared_buffers values.
Is very necessary that you have these values so high?

Regards


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Ing. Marcos Luís Ortíz Valmaseda
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Centro de Tecnologías de Almacenamiento y Análisis de Datos (CENTALAD)
Universidad de las Ciencias Informáticas

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