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Repair error apparently introduced in the initial coding of GUC: the

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default value for geqo_effort is supposed to be 40, not 1.  The actual
'genetic' component of the GEQO algorithm has been practically disabled
since 7.1 because of this mistake.  Improve documentation while at it.
This commit is contained in:
Tom Lane
2004-01-21 23:33:34 +00:00
parent 4d2e94ef04
commit 672a807028
5 changed files with 55 additions and 38 deletions
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28
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
*
* $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.41 2003/11/29 19:51:50 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.42 2004/01/21 23:33:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -38,13 +38,13 @@
* Configuration options
*/
int Geqo_pool_size;
int Geqo_effort;
int Geqo_generations;
int Geqo_effort;
double Geqo_selection_bias;
static int gimme_pool_size(int nr_rel);
static int gimme_number_generations(int pool_size, int effort);
static int gimme_number_generations(int pool_size);
/* define edge recombination crossover [ERX] per default */
#if !defined(ERX) && \
@@ -92,7 +92,7 @@ geqo(Query *root, int number_of_rels, List *initial_rels)
/* set GA parameters */
pool_size = gimme_pool_size(number_of_rels);
number_generations = gimme_number_generations(pool_size, Geqo_effort);
number_generations = gimme_number_generations(pool_size);
status_interval = 10;
/* allocate genetic pool memory */
@@ -284,7 +284,7 @@ gimme_pool_size(int nr_rel)
{
double size;
if (Geqo_pool_size != 0)
if (Geqo_pool_size > 0)
return Geqo_pool_size;
size = pow(2.0, nr_rel + 1.0);
@@ -305,10 +305,20 @@ gimme_pool_size(int nr_rel)
* = Effort * Log2(PoolSize)
*/
static int
gimme_number_generations(int pool_size, int effort)
gimme_number_generations(int pool_size)
{
if (Geqo_generations <= 0)
return effort * (int) ceil(log((double) pool_size) / log(2.0));
else
double gens;
if (Geqo_generations > 0)
return Geqo_generations;
gens = Geqo_effort * log((double) pool_size) / log(2.0);
/* bound it to a sane range */
if (gens <= 0)
gens = 1;
else if (gens > 10000)
gens = 10000;
return (int) ceil(gens);
}