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/*------------------------------------------------------------------------
*
* geqo_main.c--
* solution of the query optimization problem
* by means of a Genetic Algorithm (GA)
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: geqo_main.c,v 1.7 1998/02/26 04:32:22 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/* contributed by:
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
* Martin Utesch * Institute of Automatic Control *
= = University of Mining and Technology =
* utesch@aut.tu-freiberg.de * Freiberg, Germany *
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
*/
/* -- parts of this are adapted from D. Whitley's Genitor algorithm -- */
#include "postgres.h"
#include "nodes/pg_list.h"
#include "nodes/relation.h"
#include "nodes/plannodes.h"
#include "nodes/primnodes.h"
#include "utils/palloc.h"
#include "utils/elog.h"
#include "optimizer/internal.h"
#include "optimizer/paths.h"
#include "optimizer/pathnode.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/geqo_gene.h"
#include "optimizer/geqo.h"
#include "optimizer/geqo_pool.h"
#include "optimizer/geqo_selection.h"
#include "optimizer/geqo_recombination.h"
#include "optimizer/geqo_mutation.h"
#include "optimizer/geqo_misc.h"
/* define edge recombination crossover [ERX] per default */
#if !defined(ERX) && \
!defined(PMX) && \
!defined(CX) && \
!defined(PX) && \
!defined(OX1) && \
!defined(OX2)
#define ERX
#endif
/*
* geqo--
* solution of the query optimization problem
* similar to a constrained Traveling Salesman Problem (TSP)
*/
Rel *
geqo(Query *root)
{
int generation;
Chromosome *momma;
Chromosome *daddy;
Chromosome *kid;
#if defined(ERX)
Edge *edge_table; /* list of edges */
int edge_failures = 0;
float difference;
#endif
#if defined(CX) || defined(PX) || defined(OX1) || defined(OX2)
City *city_table; /* list of cities */
#endif
#if defined(CX)
int cycle_diffs = 0;
int mutations = 0;
#endif
int number_of_rels;
Pool *pool;
int pool_size,
number_generations,
status_interval;
Gene *best_tour;
Rel *best_rel;
/* Plan *best_plan; */
/* set tour size */
number_of_rels = length(root->base_relation_list_);
/* set GA parameters */
geqo_params(number_of_rels);/* out of "$PGDATA/pg_geqo" file */
pool_size = PoolSize;
number_generations = Generations;
status_interval = 10;
/* seed random number generator */
srandom(RandomSeed);
/* allocate genetic pool memory */
pool = alloc_pool(pool_size, number_of_rels);
/* random initialization of the pool */
random_init_pool(root, pool, 0, pool->size);
/* sort the pool according to cheapest path as fitness */
sort_pool(pool); /* we have to do it only one time, since
* all kids replace the worst individuals
* in future (-> geqo_pool.c:spread_chromo
* ) */
/* allocate chromosome momma and daddy memory */
momma = alloc_chromo(pool->string_length);
daddy = alloc_chromo(pool->string_length);
#if defined (ERX)
elog(DEBUG, "geqo_main: using edge recombination crossover [ERX]");
/* allocate edge table memory */
edge_table = alloc_edge_table(pool->string_length);
#elif defined(PMX)
elog(DEBUG, "geqo_main: using partially matched crossover [PMX]");
/* allocate chromosome kid memory */
kid = alloc_chromo(pool->string_length);
#elif defined(CX)
elog(DEBUG, "geqo_main: using cycle crossover [CX]");
/* allocate city table memory */
kid = alloc_chromo(pool->string_length);
city_table = alloc_city_table(pool->string_length);
#elif defined(PX)
elog(DEBUG, "geqo_main: using position crossover [PX]");
/* allocate city table memory */
kid = alloc_chromo(pool->string_length);
city_table = alloc_city_table(pool->string_length);
#elif defined(OX1)
elog(DEBUG, "geqo_main: using order crossover [OX1]");
/* allocate city table memory */
kid = alloc_chromo(pool->string_length);
city_table = alloc_city_table(pool->string_length);
#elif defined(OX2)
elog(DEBUG, "geqo_main: using order crossover [OX2]");
/* allocate city table memory */
kid = alloc_chromo(pool->string_length);
city_table = alloc_city_table(pool->string_length);
#endif
/* my pain main part: */
/* iterative optimization */
for (generation = 0; generation < number_generations; generation++)
{
/* SELECTION */
geqo_selection(momma, daddy, pool, SelectionBias); /* using linear bias
* function */
#if defined (ERX)
/* EDGE RECOMBINATION CROSSOVER */
difference = gimme_edge_table(momma->string, daddy->string, pool->string_length, edge_table);
/* let the kid grow in momma's womb (storage) for nine months ;-) */
/* sleep(23328000) -- har har har */
kid = momma;
/* are there any edge failures ? */
edge_failures += gimme_tour(edge_table, kid->string, pool->string_length);
#elif defined(PMX)
/* PARTIALLY MATCHED CROSSOVER */
pmx(momma->string, daddy->string, kid->string, pool->string_length);
#elif defined(CX)
/* CYCLE CROSSOVER */
cycle_diffs =
cx(momma->string, daddy->string, kid->string, pool->string_length, city_table);
/* mutate the child */
if (cycle_diffs == 0)
{
mutations++;
geqo_mutation(kid->string, pool->string_length);
}
#elif defined(PX)
/* POSITION CROSSOVER */
px(momma->string, daddy->string, kid->string, pool->string_length, city_table);
#elif defined(OX1)
/* ORDER CROSSOVER */
ox1(momma->string, daddy->string, kid->string, pool->string_length, city_table);
#elif defined(OX2)
/* ORDER CROSSOVER */
ox2(momma->string, daddy->string, kid->string, pool->string_length, city_table);
#endif
/* EVALUATE FITNESS */
kid->worth = geqo_eval(root, kid->string, pool->string_length);
/* push the kid into the wilderness of life according to its worth */
spread_chromo(kid, pool);
#ifdef GEQO_DEBUG
if (status_interval && !(generation % status_interval))
print_gen(stdout, pool, generation);
#endif
} /* end of iterative optimization */
#if defined(ERX) && defined(GEQO_DEBUG)
if (edge_failures != 0)
fprintf(stdout, "\nFailures: %d Avg: %d\n", edge_failures, (int) generation / edge_failures);
else
fprintf(stdout, "No edge failures detected.\n");
#endif
#if defined(CX) && defined(GEQO_DEBUG)
if (mutations != 0)
fprintf(stdout, "\nMutations: %d Generations: %d\n", mutations, generation);
else
fprintf(stdout, "No mutations processed.\n");
#endif
#ifdef GEQO_DEBUG
fprintf(stdout, "\n");
print_pool(stdout, pool, 0, pool_size - 1);
#endif
/* got the cheapest query tree processed by geqo;
first element of the population indicates the best query tree */
best_tour = (Gene *) pool->data[0].string;
/* root->join_relation_list_ will be modified during this ! */
best_rel = (Rel *) gimme_tree(root, best_tour, 0, pool->string_length, NULL);
/* DBG: show the query plan
print_plan(best_plan, root);
DBG */
/* ... free memory stuff */
free_chromo(momma);
free_chromo(daddy);
#if defined (ERX)
free_edge_table(edge_table);
#elif defined(PMX)
free_chromo(kid);
#elif defined(CX)
free_chromo(kid);
free_city_table(city_table);
#elif defined(PX)
free_chromo(kid);
free_city_table(city_table);
#elif defined(OX1)
free_chromo(kid);
free_city_table(city_table);
#elif defined(OX2)
free_chromo(kid);
free_city_table(city_table);
#endif
free_pool(pool);
return (best_rel);
}
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