Robert Haas <robertmh...@gmail.com> writes: > The blog post to which Parag linked includes this histogram as an > example of a low-Hamming-weight situation:
That's an interesting post indeed, but I'm not sure how relevant it is to us, because it is about Xoshiro not Xoroshiro, and the latter is what we use. The last sentence of the blog post is In this case, a mix of practice and theory has shown that the structure of Xoshiro's state space is poorer than that of many competing generation schemes, including Blackman's gjrand and perhaps even Vigna and Blackman's earlier Xoroshiro scheme (which has smaller zeroland expanses and does not appear to have similar close-repeat problems), and its output functions are unable to completely conceal these issues. So while pg_prng.c might have the issue posited here, this blog post is not evidence for that, and indeed might be evidence against it. Someone would have to do similar analysis on the code we *actually* use to convince me that we need to worry. regards, tom lane