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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
View File

@@ -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);

11
src/backend/utils/misc/guc.c
View File

@@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.155 2003/09/04 05:11:20 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.156 2003/09/07 15:26:53 tgl Exp $
*
*--------------------------------------------------------------------
*/
@@ -898,15 +898,6 @@ static struct config_int ConfigureNamesInt[] =
&Geqo_generations,
0, 0, INT_MAX, NULL, NULL
},
{
{"geqo_random_seed", PGC_USERSET, QUERY_TUNING_GEQO,
gettext_noop("Can be set to get reproducible results from the algorithm"),
gettext_noop("If it is set to -1 then the algorithm behaves "
"non-deterministically")
},
&Geqo_random_seed,
-1, INT_MIN, INT_MAX, NULL, NULL
},
{
{"deadlock_timeout", PGC_SIGHUP, LOCK_MANAGEMENT,

1
src/backend/utils/misc/postgresql.conf.sample
View File

@@ -121,7 +121,6 @@
#geqo_generations = 0
#geqo_pool_size = 0 # default based on tables in statement,
# range 128-1024
#geqo_random_seed = -1 # -1 = use variable seed
#geqo_selection_bias = 2.0 # range 1.5-2.0
# - Other Planner Options -