Re: random() function documentation

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Dagfinn Ilmari Mannsåker <ilmari(at)ilmari(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: random() function documentation
Date: 2022-04-12 08:19:07
Message-ID: alpine.DEB.2.22.394.2204120950260.1378296@pseudo
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>>>> How about we just say "uses a linear-feedback shift register algorithm"?
>
> I think it'd be sufficient to just say that it's a deterministic
> pseudorandom number generator. I don't see much value in documenting
> the internal algorithm used.

Hmmm… I'm not so sure. ISTM that people interested in using the random
user-facing variants (only random?) could like a pointer on the algorithm
to check for the expected quality of the produced pseudo-random stream?

See attached.

>>> Should we perhaps also add a warning that the same seed is not
>>> guaranteed to produce the same sequence across different (major?)
>>> versions?
>>
>> I wouldn't bother, on the grounds that then we'd need such disclaimers
>> in a whole lot of places. Others might see it differently though.
>
> Agreed,

Agreed.

> though I think when the release notes are written, they ought
> to warn that the sequence will change with this release.

Yes.

--
Fabien.

Attachment Content-Type Size
random-algo.patch text/x-diff 1.0 KB

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