Re: shared memory

On Mon, 17 Jun 2002, Jan Wieck wrote:

> Of course is increasing the number of shared buffers beneficial. It
> usually increases the buffer hit rate in turn, causing lesser IO
> operations and thus increasing the overall performance.

Yes, but the only savings may be in transferring the buffer between
the operating system's buffer cache and the postgres buffer cache.
Remember, the OS is doing buffering as well.

> If you're
> setting up a dedicated DB server, I'd suggest starting with half of the
> physical RAM configured as shared buffers and experimenting from there.

I'd guess that "half" is about the very worst value you could chose.
That will maximize the number of pages that are stored (in duplicate)
in both the OS and postgres buffers, and waste a lot of memory.

cjs
--
Curt Sampson  <cjs@cynic.net>   +81 90 7737 2974   http://www.netbsd.org
    Don't you know, in this new Dark Age, we're all light.  --XTC