Re: gaussian distribution pgbench

On 20/12/13 09:36, Peter Geoghegan wrote:
> On Thu, Nov 21, 2013 at 9:13 AM, Heikki Linnakangas
> <hlinnakangas@vmware.com> wrote:
>> So what I'd actually like to see is \setgaussian, for use in custom scripts.
> +1. I'd really like to be able to run a benchmark with a Gaussian and
> uniform distribution side-by-side for comparative purposes - we need
> to know that we're not optimizing one at the expense of the other.
> Sure, DBT-2 gets you a non-uniform distribution, but it has serious
> baggage from it being a tool primarily intended for measuring the
> relative performance of different database systems. pgbench would be
> pretty worthless for measuring the relative strengths and weaknesses
> of different database systems, but it is not bad at informing the
> optimization efforts of hackers. pgbench is a defacto standard for
> that kind of thing, so we should make it incrementally better for that
> kind of thing. No standard industry benchmark is likely to replace it
> for this purpose, because such optimizations require relatively narrow
> focus.
>
> Sometimes I want to maximally pessimize the number of FPIs generated.
> Other times I do not. Getting a sense of how something affects a
> variety of distributions would be very valuable, not least since
> normal distributions abound in nature.
>
>
Curious, wouldn't the common usage pattern tend to favour a skewed 
distribution, such as the  Poisson Distribution (it has been over 40 
years since I studied this area, so there may be better candidates).

Just that gut feeling & experience tends to make me think that the 
"Normal" distribution may often not be the best for database access 
simulation.


Cheers,
Gavin