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Commit672a807

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Repair error apparently introduced in the initial coding of GUC: the
default value for geqo_effort is supposed to be 40, not 1. The actual'genetic' component of the GEQO algorithm has been practically disabledsince 7.1 because of this mistake. Improve documentation while at it.
1 parent4d2e94e commit672a807

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5 files changed

+55
-38
lines changed

5 files changed

+55
-38
lines changed

‎doc/src/sgml/runtime.sgml

Lines changed: 13 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.230 2004/01/10 23:28:43 neilc Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.231 2004/01/21 23:33:34 tgl Exp $
33
-->
44

55
<Chapter Id="runtime">
@@ -1404,23 +1404,25 @@ SET ENABLE_SEQSCAN TO OFF;
14041404
</varlistentry>
14051405

14061406
<varlistentry>
1407-
<term><varname>geqo_effort</varname> (<type>integer</type>)</term>
1408-
<term><varname>geqo_generations</varname> (<type>integer</type>)</term>
14091407
<term><varname>geqo_pool_size</varname> (<type>integer</type>)</term>
1408+
<term><varname>geqo_generations</varname> (<type>integer</type>)</term>
1409+
<term><varname>geqo_effort</varname> (<type>integer</type>)</term>
14101410
<term><varname>geqo_selection_bias</varname> (<type>floating point</type>)</term>
14111411
<listitem>
14121412
<para>
14131413
Various tuning parameters for the genetic query optimization
1414-
algorithm: The pool size is the number of individuals in one
1414+
algorithm. The pool size is the number of individuals in one
14151415
population. Valid values are between 128 and 1024. If it is set
14161416
to 0 (the default) a pool size of 2^(QS+1), where QS is the
1417-
number of <literal>FROM</> items in the query, is taken. The effort is used
1418-
to calculate a default for generations. Valid values are between
1419-
1 and 80, 40 being the default. Generations specifies the number
1420-
of iterations in the algorithm. The number must be a positive
1421-
integer. If 0 is specified then <literal>Effort *
1422-
Log2(PoolSize)</literal> is used. The run time of the algorithm
1423-
is roughly proportional to the sum of pool size and generations.
1417+
number of <literal>FROM</> items in the query, is used.
1418+
Generations specifies the number of iterations of the algorithm.
1419+
The value must be a positive integer. If 0 is specified then
1420+
<literal>Effort * Log2(PoolSize)</literal> is used.
1421+
The run time of the algorithm is roughly proportional to the sum of
1422+
pool size and generations.
1423+
<varname>geqo_effort</varname> is only used in computing the default
1424+
generations setting, as just described. The default value is 40,
1425+
and the allowed range 1 to 100.
14241426
The selection bias is the selective pressure within the
14251427
population. Values can be from 1.50 to 2.00; the latter is the
14261428
default.

‎src/backend/optimizer/geqo/geqo_main.c

Lines changed: 19 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.41 2003/11/29 19:51:50 pgsql Exp $
10+
* $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.42 2004/01/21 23:33:34 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -38,13 +38,13 @@
3838
* Configuration options
3939
*/
4040
intGeqo_pool_size;
41-
intGeqo_effort;
4241
intGeqo_generations;
42+
intGeqo_effort;
4343
doubleGeqo_selection_bias;
4444

4545

4646
staticintgimme_pool_size(intnr_rel);
47-
staticintgimme_number_generations(intpool_size,inteffort);
47+
staticintgimme_number_generations(intpool_size);
4848

4949
/* define edge recombination crossover [ERX] per default */
5050
#if !defined(ERX)&& \
@@ -92,7 +92,7 @@ geqo(Query *root, int number_of_rels, List *initial_rels)
9292

9393
/* set GA parameters */
9494
pool_size=gimme_pool_size(number_of_rels);
95-
number_generations=gimme_number_generations(pool_size,Geqo_effort);
95+
number_generations=gimme_number_generations(pool_size);
9696
status_interval=10;
9797

9898
/* allocate genetic pool memory */
@@ -284,7 +284,7 @@ gimme_pool_size(int nr_rel)
284284
{
285285
doublesize;
286286

287-
if (Geqo_pool_size!=0)
287+
if (Geqo_pool_size>0)
288288
returnGeqo_pool_size;
289289

290290
size=pow(2.0,nr_rel+1.0);
@@ -305,10 +305,20 @@ gimme_pool_size(int nr_rel)
305305
* = Effort * Log2(PoolSize)
306306
*/
307307
staticint
308-
gimme_number_generations(intpool_size,inteffort)
308+
gimme_number_generations(intpool_size)
309309
{
310-
if (Geqo_generations <=0)
311-
returneffort* (int)ceil(log((double)pool_size) /log(2.0));
312-
else
310+
doublegens;
311+
312+
if (Geqo_generations>0)
313313
returnGeqo_generations;
314+
315+
gens=Geqo_effort*log((double)pool_size) /log(2.0);
316+
317+
/* bound it to a sane range */
318+
if (gens <=0)
319+
gens=1;
320+
elseif (gens>10000)
321+
gens=10000;
322+
323+
return (int)ceil(gens);
314324
}

‎src/backend/utils/misc/guc.c

Lines changed: 11 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Written by Peter Eisentraut <peter_e@gmx.net>.
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.177 2004/01/19 19:04:40 tgl Exp $
13+
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.178 2004/01/21 23:33:34 tgl Exp $
1414
*
1515
*--------------------------------------------------------------------
1616
*/
@@ -931,23 +931,23 @@ static struct config_int ConfigureNamesInt[] =
931931
&Geqo_pool_size,
932932
DEFAULT_GEQO_POOL_SIZE,0,MAX_GEQO_POOL_SIZE,NULL,NULL
933933
},
934-
{
935-
{"geqo_effort",PGC_USERSET,QUERY_TUNING_GEQO,
936-
gettext_noop("GEQO: effort is used to calculate a default for generations."),
937-
NULL
938-
},
939-
&Geqo_effort,
940-
1,1,INT_MAX,NULL,NULL
941-
},
942934
{
943935
{"geqo_generations",PGC_USERSET,QUERY_TUNING_GEQO,
944-
gettext_noop("GEQO: number of iterationsin the algorithm."),
945-
gettext_noop("Thenumber must be a positive integer. If 0 is "
936+
gettext_noop("GEQO: number of iterationsof the algorithm."),
937+
gettext_noop("Thevalue must be a positive integer. If 0 is "
946938
"specified then effort * log2(poolsize) is used.")
947939
},
948940
&Geqo_generations,
949941
0,0,INT_MAX,NULL,NULL
950942
},
943+
{
944+
{"geqo_effort",PGC_USERSET,QUERY_TUNING_GEQO,
945+
gettext_noop("GEQO: effort is used to set the default for generations."),
946+
NULL
947+
},
948+
&Geqo_effort,
949+
DEFAULT_GEQO_EFFORT,MIN_GEQO_EFFORT,MAX_GEQO_EFFORT,NULL,NULL
950+
},
951951

952952
{
953953
{"deadlock_timeout",PGC_SIGHUP,LOCK_MANAGEMENT,

‎src/backend/utils/misc/postgresql.conf.sample

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -123,10 +123,10 @@
123123

124124
#geqo = true
125125
#geqo_threshold = 11
126-
#geqo_effort = 1
127-
#geqo_generations = 0
128126
#geqo_pool_size = 0# default based on tables in statement,
129127
# range 128-1024
128+
#geqo_generations = 0# use default: effort * log2(pool_size)
129+
#geqo_effort = 40# range 1-100
130130
#geqo_selection_bias = 2.0# range 1.5-2.0
131131

132132
# - Other Planner Options -

‎src/include/optimizer/geqo.h

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/include/optimizer/geqo.h,v 1.33 2003/11/29 22:41:07 pgsql Exp $
9+
* $PostgreSQL: pgsql/src/include/optimizer/geqo.h,v 1.34 2004/01/21 23:33:34 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -44,22 +44,27 @@
4444

4545
/*
4646
* Configuration options
47+
*
48+
* If you change these, update backend/utils/misc/postgresql.sample.conf
4749
*/
48-
/* If you change these, update backend/utils/misc/postgresql.sample.conf */
4950
externintGeqo_pool_size;
5051

5152
#defineDEFAULT_GEQO_POOL_SIZE 0/* = default based on no. of relations. */
5253
#defineMIN_GEQO_POOL_SIZE 128
5354
#defineMAX_GEQO_POOL_SIZE 1024
5455

55-
externintGeqo_effort;/* 1 .. inf, only used to calculate
56-
* generations default */
5756
externintGeqo_generations;/* 1 .. inf, or 0 to use default based on
5857
* pool size */
5958

59+
externintGeqo_effort;/* only used to calculate default for
60+
* generations */
61+
62+
#defineDEFAULT_GEQO_EFFORT 40
63+
#defineMIN_GEQO_EFFORT 1
64+
#defineMAX_GEQO_EFFORT 100
65+
6066
externdoubleGeqo_selection_bias;
6167

62-
/* If you change these, update backend/utils/misc/postgresql.sample.conf */
6368
#defineDEFAULT_GEQO_SELECTION_BIAS 2.0
6469
#defineMIN_GEQO_SELECTION_BIAS 1.5
6570
#defineMAX_GEQO_SELECTION_BIAS 2.0

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