Sorry for my delay reply.
Since I have had vacation last week, I replied from gmail.
However, it was stalled post to pgsql-hackers:-(
(2013/09/21 7:54), Fabien COELHO wrote:
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,
--
Mitsumasa KONDO
NTT Open Source Software Center
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