Re: Memory and performance

On Thu, Apr 05, 2001 at 10:46:07AM -0400, Tom Lane wrote:
> Tim Perdue <tim(at)perdue(dot)net> writes:
> > Our database is about 1GB in total size, the machine has 4GB, but the entire
> > system is only using 1.2 GB, even during vacuum or a daily, extremely large
> > query that requires a lot of grouping and sorting.
>
> What have you got the SortMem parameter (backend -S switch) set to?
> That's about the only use I can think of for RAM beyond what's needed to
> cache the whole database ...

-i -o -F -S 32768 -B 2048 is our startup line.

It appears to me that when you're vacuuming, it's physically moving all the
bits around the disk. It doesn't read in the table, clean out the cruft, the
flush it out. So I think this is where we're getting IO bound. We only have a
5x36 RAID - must not be sufficient.

Tim

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