On Mar 9, 2004, at 8:00 AM, Stephen Frost wrote:
> * Steve Wolfe (nw@codon.com) wrote:
>> The main question in my mind is whether a 4-way Opteron is going to
>> give me enough of a performance benefit over a 2-way Opteron to make
>> the
>> extra $10k worth it. My first guess was that it would, as going from
>> 2
>> Opterons to 4 will give you twice the potential memory bandwidth.
>> However, as PostgreSQL pulls heavily from the global buffers, I may
>> not be
>> able to utilize all of that potential bandwidth.
>
> Well, one question to ask, of course, is how much overlap is there in
> the queries? I think that'd make some difference... Besides that,
> make
> sure you get enough DIMMS (2 per CPU) to get interleaved memory access
> going on the Opterons. I'm guessing you realize this already, but
> figured I'd mention it anyway. :) When I got my opterons in I hadn't
> realized it'd do interleaved till I was flipping through the MB manual.
> :)\
And lets not forget one of the best things to do: Optimize the queries
themselves!
Nothing can beat good ol' fashion query optimization.
Wether it be adding an index or trying something out like a
materialized view.
I have a PG machine here doing over 50 queries (both read/write) and it
has plenty of idle cpu.
--
Jeff Trout <jeff@jefftrout.com>
http://www.jefftrout.com/
http://www.stuarthamm.net/
