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Remove geqo_random_seed parameter. Having geqo reset the global random()

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sequence every time it's called is bogus --- it interferes with user
control over the seed, and actually decreases randomness overall
(because a seed based on time(NULL) is pretty predictable).  If you really
want a reproducible result from geqo, do 'set seed = 0' before planning
a query.
This commit is contained in:
Tom Lane
2003-09-07 15:26:54 +00:00
parent 75c35e0f31
commit 48beecda7c
6 changed files with 6 additions and 30 deletions
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7
doc/src/sgml/runtime.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.203 2003/09/05 16:13:38 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.204 2003/09/07 15:26:45 tgl Exp $
-->
<Chapter Id="runtime">
@ -1438,7 +1438,6 @@ SET ENABLE_SEQSCAN TO OFF;
<term><varname>GEQO_EFFORT</varname> (<type>integer</type>)</term>
<term><varname>GEQO_GENERATIONS</varname> (<type>integer</type>)</term>
<term><varname>GEQO_POOL_SIZE</varname> (<type>integer</type>)</term>
<term><varname>GEQO_RANDOM_SEED</varname> (<type>integer</type>)</term>
<term><varname>GEQO_SELECTION_BIAS</varname> (<type>floating point</type>)</term>
<listitem>
<para>
@ -1455,9 +1454,7 @@ SET ENABLE_SEQSCAN TO OFF;
is roughly proportional to the sum of pool size and generations.
The selection bias is the selective pressure within the
population. Values can be from 1.50 to 2.00; the latter is the
default. The random seed can be set to get reproducible results
from the algorithm. If it is set to -1 then the algorithm
behaves non-deterministically.
default.
</para>
</listitem>
</varlistentry>