Re: gaussian distribution pgbench

> However this pattern induces stronger cache effects which are maybe not
too realistic,

> because neighboring keys in the middle are more likely to be chosen.

I think that your opinion is right. However, in effect, it is a
paseudo-benchmark, so that I think that such a simple mechanism is also
necessary.

> Have you considered adding a "randomization" layer, that is once you have
a key in [1 .. > n] centered around n/2, then you perform a pseudo-random
transformation into the same > domain so that key values are scattered over
the whole domain?

Yes. I also consider this patch. It can realize by adding linear mapping
array which is created by random generator. However, current erand48
algorithm is not high accuracy and fossil algorithm, I do not know whether
it works well. If we realize it, we may need more accurate random generator
algorithm which is like Mersenne Twister*.*

Regards,

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Mitsumasa KONDO