Very large caches (was Re: 7.3.1 New install, large queries are slow)

On Mon, 2003-01-20 at 01:14, Tom Lane wrote:
> "Shridhar Daithankar" <shridhar_daithankar@persistent.co.in> writes:
> > On 17 Jan 2003 at 12:33, Tom Lane wrote:
[snip]
> > and that is also the only way to make postgresql use more than couple of gigs
> > of RAM, isn't it?
>
> It seems quite unrelated.  The size of our shared memory segment is
> limited by INT_MAX --- chopping it up differently won't change that.
>
> In any case, I think worrying because you can't push shared buffers
> above two gigs is completely wrongheaded, for the reasons already
> discussed in this thread.  The notion that Postgres can't use more
> than two gig because its shared memory is limited to that is
> *definitely* wrongheaded.  We can exploit however much memory your
> kernel can manage for kernel disk cache.

http://www.redhat.com/services/techsupport/production/GSS_caveat.html
"RAM Limitations on IA32
Red Hat Linux releases based on the 2.4 kernel -- including Red Hat
Linux 7.1, 7.2, 7.3 and Red Hat Linux Advanced Server 2.1 -- support
a maximum of 16GB of RAM."

So if I have some honking "big" Compaq Xeon SMP server w/ 16GB RAM,
and top(1) shows that there is 8GB of buffers, then Pg will be happy
as a pig in the mud?

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