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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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10
src/backend/optimizer/geqo/geqo_main.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.39 2003/08/12 18:23:20 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.40 2003/09/07 15:26:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -41,7 +41,6 @@ int Geqo_pool_size;
int Geqo_effort;
int Geqo_generations;
double Geqo_selection_bias;
int Geqo_random_seed;
static int gimme_pool_size(int nr_rel);
@ -96,13 +95,6 @@ geqo(Query *root, int number_of_rels, List *initial_rels)
number_generations = gimme_number_generations(pool_size, Geqo_effort);
status_interval = 10;
/* seed random number generator */
/* XXX why is this done every time around? */
if (Geqo_random_seed >= 0)
srandom((unsigned int) Geqo_random_seed);
else
srandom((unsigned int) time(NULL));
/* allocate genetic pool memory */
pool = alloc_pool(pool_size, number_of_rels);