Re: how delete/insert/update affects select performace? - Mailing list pgsql-performance

From Kevin Grittner
Subject Re: how delete/insert/update affects select performace?
Date
Msg-id 4E69BA830200002500040FD2@gw.wicourts.gov
Whole thread Raw
List pgsql-performance
"Anibal David Acosta"  wrote:

>> The general guidelines for Windows servers such as
>> http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server
>> recommend a fairly small setting for the shared_buffers parameters
>> on Windows--no more than 512MB.

> Even if I have a server with 16GB of ram, I must set the
> shared_buffer to 512MB on windows?
>
> In the wiki page they talk about 1/4 of ram, in my case that
> represent a shared_buffer = 4GB, that is incorrect?

There's an effective maximum, depending on the platform.  On Linux
that seems to be somewhere in the 8GB to 10GB.  On Windows it is much
less.

> If I can't configure more than 512MB of shared_buffer all other RAM
> is unnecessary?

The RAM not used for other purposes is used by the OS for caching.
PostgreSQL goes through that cache, so the extra memory will be used;
it's a question of what balance between PostgreSQL buffers and OS
cache gives the best performance.

-Kevin

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