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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-07-23 19:00:30 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-07-23 19:00:30 -0400 |
| commit | 042554d55d8539ea621ecf25d10d8c38ff1a2324 (patch) | |
| tree | 8c19b9fa7d5f3c9efdc371faa66f7c8786455b7d | |
| parent | 32e1510150837d7bf6defa382444f7c3e9e83253 (diff) | |
| download | postgresql-042554d55d8539ea621ecf25d10d8c38ff1a2324.tar.gz postgresql-042554d55d8539ea621ecf25d10d8c38ff1a2324.zip | |
Doc: improve documentation about random().
We didn't explicitly say that random() uses a randomly-chosen seed
if you haven't called setseed(). Do so.
Also, remove ref/set.sgml's no-longer-accurate (and never very
relevant) statement that the seed value is multiplied by 2^31-1.
Back-patch to v12 where set.sgml's claim stopped being true.
The claim that we use a source of random bits as seed was debatable
before 4203842a1, too, so v12 seems like a good place to stop.
Per question from Carl Sopchak.
Discussion: https://postgr.es/m/f37bb937-9d99-08f0-4de7-80c91a3cfc2e@sopchak.me
| -rw-r--r-- | doc/src/sgml/func.sgml | 3 | ||||
| -rw-r--r-- | doc/src/sgml/ref/set.sgml | 3 |
2 files changed, 4 insertions, 2 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 8b4283e3cc4..44cc4875323 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1171,6 +1171,9 @@ subsequent <function>random()</function> calls in the current session are repeatable by re-issuing <function>setseed()</function> with the same argument. + Without any prior <function>setseed()</function> call in the same + session, the first <function>random()</function> call obtains a seed + from a platform-dependent source of random bits. </para> <para> diff --git a/doc/src/sgml/ref/set.sgml b/doc/src/sgml/ref/set.sgml index 63f312e812a..22d0e3f6e49 100644 --- a/doc/src/sgml/ref/set.sgml +++ b/doc/src/sgml/ref/set.sgml @@ -175,8 +175,7 @@ SET [ SESSION | LOCAL ] TIME ZONE { <replaceable class="parameter">timezone</rep <para> Sets the internal seed for the random number generator (the function <function>random</function>). Allowed values are - floating-point numbers between -1 and 1, which are then - multiplied by 2<superscript>31</superscript>-1. + floating-point numbers between -1 and 1 inclusive. </para> <para> |