Re: gaussian distribution pgbench

Hello Mitsumasa-san,

> And I'm also interested in your "decile percents" output like under
> followings,
> decile percents: 39.6% 24.0% 14.6% 8.8% 5.4% 3.3% 2.0% 1.2% 0.7% 0.4%

Sure, I'm really fine with that.

> I think that it is easier than before. Sum of decile percents is just 100%.

That's a good property:-)

> However, I don't prefer "highest/lowest percentage" because it will be 
> confused with decile percentage for users, and anyone cannot understand 
> this digits. I cannot understand "4.9%, 0.0%" when I see the first time. 
> Then, I checked the source code, I understood it:( It's not good 
> design... #Why this parameter use 100?

What else? People have ten fingers and like powers of 10, and are used to 
percents?

> So I'd like to remove it if you like. It will be more simple.

I think that for the exponential distribution it helps, especially for 
high threshold, to have the lowest/highest percent density. For low 
thresholds, the decile is also definitely useful. So I'm fine with both 
outputs as you have put them.

I have just updated the wording so that it may be clearer:
 decile percents: 69.9% 21.0% 6.3% 1.9% 0.6% 0.2% 0.1% 0.0% 0.0% 0.0% probability of fist/last percent of the range:
11.3%0.0%
 

> Attached patch is fixed version, please confirm it.

Attached a v15 which just fixes a typo and the above wording update. I'm 
validating it for committers.

> #Of course, World Cup is being held now. I'm not hurry at all.

I'm not a soccer kind of person, so it does not influence my 
availibility.:-)


Suggested commit message:

Add drawing random integers with a Gaussian or truncated exponentional 
distributions to pgbench.

Test variants with these distributions are also provided and triggered
with options "--gaussian=..." and "--exponential=...".


Have a nice day/night,

-- 
Fabien.