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Document and enforce that the usable range of setseed() arguments is

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-1 to 1, not 0 to 1.  The actual behavior for values within this range
does not change.  Kris Jurka
This commit is contained in:
Tom Lane 2008-03-10 12:39:23 +00:00
parent bfce56eea4
commit 23c356ccec
4 changed files with 12 additions and 8 deletions
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4
doc/src/sgml/func.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.423 2008/03/06 18:49:32 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.424 2008/03/10 12:39:22 tgl Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
@ -828,7 +828,7 @@
<row>
<entry><literal><function>setseed</function>(<type>dp</type>)</literal></entry>
<entry><type>void</type></entry>
<entry>set seed for subsequent <literal>random()</literal> calls (value between 0 and 1.0)</entry>
<entry>set seed for subsequent <literal>random()</literal> calls (value between -1.0 and 1.0)</entry>
<entry><literal>setseed(0.54823)</literal></entry>
<entry></entry>
</row>

4
doc/src/sgml/ref/set.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/set.sgml,v 1.91 2007/09/11 00:06:41 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/set.sgml,v 1.92 2008/03/10 12:39:22 tgl Exp $
PostgreSQL documentation
-->
@ -166,7 +166,7 @@ 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 0 and 1, which are then
floating-point numbers between -1 and 1, which are then
multiplied by 2<superscript>31</>-1.
</para>

8
src/backend/utils/adt/float.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.153 2008/01/01 19:45:52 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.154 2008/03/10 12:39:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1684,8 +1684,12 @@ Datum
setseed(PG_FUNCTION_ARGS)
{
float8 seed = PG_GETARG_FLOAT8(0);
int iseed = (int) (seed * MAX_RANDOM_VALUE);
int iseed;
if (seed < -1 || seed > 1)
elog(ERROR, "setseed parameter %f out of range [-1,1]", seed);
iseed = (int) (seed * MAX_RANDOM_VALUE);
srandom((unsigned int) iseed);
PG_RETURN_VOID();

4
src/backend/utils/misc/guc.c
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@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.435 2008/03/10 03:22:29 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.436 2008/03/10 12:39:23 tgl Exp $
*
*--------------------------------------------------------------------
*/
@ -1849,7 +1849,7 @@ static struct config_real ConfigureNamesReal[] =
GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
},
&phony_random_seed,
0.5, 0.0, 1.0, assign_random_seed, show_random_seed
0.0, -1.0, 1.0, assign_random_seed, show_random_seed
},
{