Re: Need help with 8.4 Performance Testing

On Mon, Dec 8, 2008 at 1:15 PM, Greg Smith <gsmith@gregsmith.com> wrote:
> On Sun, 7 Dec 2008, Scott Marlowe wrote:
>
>> When I last used pgbench I wanted to test it with an extremely large
>> dataset, but it maxes out at -s 4xxx or so, and that's only in the
>> 40Gigabyte range.  Is the limit raised for the pgbench included in
>> contrib in 8.4?  I'm guessing it's an arbitrary limit.
>
> There's no artificial limit, just ones that result from things like integer
> overflow.  I don't think has been an issue so far because pgbench becomes
> seek limited and stops producing interesting results once the database
> exceeds the sum of all available caching, which means you'd need more than
> 32GB of RAM in the system running pgbench before this is an issue.  Which
> happens to be the largest size system I've ever ran it on...

Well, I have 32 Gig of ram and wanted to test it against a database
that was at least twice as big as memory.  I'm not sure why you'd
consider the results uninteresting though, I'd think knowing how the
db will perform with a very large transactional store that is twice or
more the size of memory would be when it starts getting interesting.