#include "postgres.h"

#include "fmgr.h"
#include "optimizer/geqo.h"
#include "optimizer/paths.h"
#include "optimizer/pathnode.h"


PG_MODULE_MAGIC;

void	_PG_init(void);
void	_PG_fini(void);

static RelOptInfo *
my_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
{
	RelOptInfo *dynamic_result, *geqo_result;
	Cost dynamic_cost, geqo_cost;
	List	   *dynamic_list, *geqo_list;
	struct HTAB *dynamic_hash, *geqo_hash;
	int			savelength;

	savelength = list_length(root->join_rel_list);

	root->join_rel_hash = NULL;

	elog(LOG, "Starting a join order search \"dynamic\"...");
	dynamic_result = standard_join_search(root, levels_needed, initial_rels);
	dynamic_cost = dynamic_result->cheapest_total_path->total_cost;

	dynamic_list = list_copy(root->join_rel_list);
	dynamic_hash = root->join_rel_hash;

	root->join_rel_list = list_truncate(root->join_rel_list,
										savelength);
	root->join_rel_hash = NULL;

	elog(LOG, "Starting a join order search \"geqo\"...");
	geqo_result = geqo(root, levels_needed, initial_rels);
	geqo_cost = geqo_result->cheapest_total_path->total_cost;

	geqo_list = list_copy(root->join_rel_list);
	geqo_hash = root->join_rel_hash;

	fprintf(stderr, "GEQO cost: %f  Dynamic programming cost: %f\n",
			geqo_cost, dynamic_cost);
	
	if (geqo_cost < dynamic_cost)
	{
		root->join_rel_list = geqo_list;
		root->join_rel_hash = geqo_hash;
		return geqo_result;
	}
	else
	{
		root->join_rel_list = dynamic_list;
		root->join_rel_hash = dynamic_hash;
		return dynamic_result;
	}
}


void
_PG_init(void)
{
	join_search_hook = my_join_search;
}

void
_PG_fini(void)
{
	join_search_hook = NULL;
}