| From: | Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> |
|---|---|
| To: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, David Steele <david(at)pgmasters(dot)net>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Hironobu SUZUKI <hironobu(at)interdb(dot)jp>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: pgbench - add pseudo-random permutation function |
| Date: | 2021-03-30 19:44:05 |
| Message-ID: | CAEZATCUEkKMFPWZWgS7c0Fe=XxD3GgPKoXK+aoyq_Bt=sNVQBA@mail.gmail.com |
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On Tue, 30 Mar 2021 at 20:31, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> wrote:
>
> Yeah, that's probably a fair point. However, all the existing pgbench
> random functions are using it, so I think it's fair enough for
> permute() to do the same (and actually 2^48 is pretty huge). Switching
> to a 64-bit PRNG might not be a bad idea, but I think that's something
> we'd want to do across the board, and so I think it should be out of
> scope for this patch.
>
Of course the immediate counter-argument to changing the existing
random functions would be that doing so would break lots of people's
tests, and no one would thank us for that. Still, I think that, since
the existing random functions use a 48-bit PRNG, it's not unreasonable
for permute() to do the same.
Regards,
Dean
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