Algorithm works with theta less than 1. The only problem here is that
theta can not be 1, because of next line of code
cell->alpha = 1. / (1 - theta);
That’s why I put such restriction. Now I see 2 possible solutions for that:
1) Exclude 1, and allow everything in range (0;+∞).
Yep.
2) Or just increase/decrease theta by very small number if it is 1.
Nope, this seems quite arbitrary.
I've executed scripts that you attached with different theta and number
of outcomes(not n, n remains the same = 100) and I found out that for
theta = 0.1 and big number of outcomes it gives distribution very
similar to zipfian(for number of outcomes = 100 000, bias -6% to 8% in
whole range and for NOO = 1000 000, bias is -2% to 2%).
Ok, so you did not get the large bias for i=3. Strange.
By, number of outcomes(NOO) I mean how many times random_zipfian was
called. For example: pgbench -f compte_bench.sql -t 100000 So, I think
it works but works worse for small number of outcomes. And also we need
to find optimal theta for better results.
Hmmm. I've run one million outcomes each time.
I'll check on the next version.
--
Fabien.
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