From: =?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: random() function documentation
References: <875ynfpiru.fsf@wibble.ilmari.org>
	<432790.1649702719@sss.pgh.pa.us>
Date: Mon, 11 Apr 2022 20:00:26 +0100
In-Reply-To: <432790.1649702719@sss.pgh.pa.us> (Tom Lane's message of "Mon, 11
	Apr 2022 14:45:19 -0400")
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Tom Lane <tgl@sss.pgh.pa.us> writes:

> =?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org> writes:
>> I just noticed that the since the random() rewrite¹, the documentation's
>> claim² that it "uses a simple linear congruential algorithm" is no
>> longer accurate (xoroshiro128** is an xorshift variant, which is a
>> linear-feedback shift register algorithm).
>
>> I don't have a suggestion for the exact wording, since I don't know
>> whether xoroshiro128** qualifies as "simple", or to what level of
>> specificity we want to document the algorithm.
>
> How about we just say "uses a linear-feedback shift register algorithm"?

That works for me.  Nice and simple, and not overly specific.  Should we
perhaps also add a warning that the same seed is not guaranteed to
produce the same sequence across different (major?) versions?

> "Simple" is in the eye of the beholder anyway.

Indeed.

> 			regards, tom lane

- ilmari