Horton

Re: What seed does random() use if setseed() is not called first?

Carl Sopchak <carl@sopchak.me>

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From: Carl Sopchak <carl@sopchak.me>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-sql@lists.postgresql.org
Date: 2022-07-23T21:55:40Z
Lists: pgsql-sql

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    <p>Thank you for the quick reply!  But I wouldn't have bothered you
      if the documentation stated something to the effect of "While it's
      platform-dependent, if setseed() is not called, the random number
      generator is generally seeded by whatever method the operating
      system provides as a source of randomness, such as /dev/urandom on
      Linux/Unix, or &lt;???&gt; on Windows."</p>
    <p>Just a suggestion, hope this helps, and thanks again!</p>
    <p>Carl<br>
    </p>
    <div class="moz-cite-prefix">On 7/23/22 17:47, Tom Lane wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:1220338.1658612839@sss.pgh.pa.us">
      <pre class="moz-quote-pre" wrap="">Carl Sopchak <a class="moz-txt-link-rfc2396E" href="mailto:carl@sopchak.me">&lt;carl@sopchak.me&gt;</a> writes:
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      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">    &lt;p&gt;There is one point about the documentation for random() and
      setseed() that is missing.  What is used to seed random() if
      setseed() isn't called first?  I assume it's something like
      /dev/random or /dev/urandom, but that's just a guess.  Can someone
      please enlighten me?&lt;/p&gt;
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      <pre class="moz-quote-pre" wrap="">
We don't document this because it's platform- and version-dependent,
but yeah, generally /dev/urandom or local equivalent.

			regards, tom lane
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Commits

  1. Doc: improve documentation about random().