PostgreSQL/src/backend/optimizer/geqo/geqo_eval.c

/*------------------------------------------------------------------------
 *
 * geqo_eval.c--
 *	  Routines to evaluate query trees
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 * $Id: geqo_eval.c,v 1.22 1998/08/10 02:26:16 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

/* contributed by:
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
   *  Martin Utesch				 * Institute of Automatic Control	   *
   =							 = University of Mining and Technology =
   *  utesch@aut.tu-freiberg.de  * Freiberg, Germany				   *
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
 */

#include "postgres.h"

#include <math.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#ifndef MAXINT
#define MAXINT INT_MAX
#endif
#else
#include <values.h>
#endif

#include "nodes/pg_list.h"
#include "nodes/relation.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/tlist.h"
#include "optimizer/joininfo.h"

#include "optimizer/geqo_gene.h"
#include "optimizer/geqo.h"
#include "optimizer/geqo_paths.h"


static List *gimme_clause_joins(Query *root, RelOptInfo *outer_rel, RelOptInfo *inner_rel);
static RelOptInfo *gimme_clauseless_join(RelOptInfo *outer_rel, RelOptInfo *inner_rel);
static RelOptInfo *init_join_rel(RelOptInfo *outer_rel, RelOptInfo *inner_rel, JInfo *joininfo);
static List *new_join_tlist(List *tlist, List *other_relids, int first_resdomno);
static List *new_joininfo_list(List *joininfo_list, List *join_relids);
static void geqo_joinrel_size(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel);
static RelOptInfo *geqo_nth(int stop, List *rels);

/*
 * geqo_eval--
 *
 * Returns cost of a query tree as an individual of the population.
 */
Cost
geqo_eval(Query *root, Gene *tour, int num_gene)
{
	RelOptInfo		   *joinrel;
	Cost		fitness;
	List	   *temp;


/* remember root->join_rel_list ... */
/* because root->join_rel_list will be changed during the following */
	temp = listCopy(root->join_rel_list);

/* joinrel is readily processed query tree -- left-sided ! */
	joinrel = gimme_tree(root, tour, 0, num_gene, NULL);

/* compute fitness */
	fitness = (Cost) joinrel->cheapestpath->path_cost;

	root->join_rel_list = listCopy(temp);

	pfree(joinrel);
	freeList(temp);

	return (fitness);

}

/*
 * gimme-tree --
 *	  this program presumes that only LEFT-SIDED TREES are considered!
 *
 * 'outer_rel' is the preceeding join
 *
 * Returns a new join relation incorporating all joins in a left-sided tree.
 */
RelOptInfo *
gimme_tree(Query *root, Gene *tour, int rel_count, int num_gene, RelOptInfo *outer_rel)
{
	RelOptInfo		   *inner_rel;		/* current relation */
	int			base_rel_index;

	List	   *new_rels = NIL;
	RelOptInfo		   *new_rel = NULL;

	if (rel_count < num_gene)
	{							/* tree not yet finished */

		/* tour[0] = 3; tour[1] = 1; tour[2] = 2 */
		base_rel_index = (int) tour[rel_count];

		inner_rel = (RelOptInfo *) geqo_nth(base_rel_index, root->base_rel_list);

		if (rel_count == 0)
		{						/* processing first join with
								 * base_rel_index = (int) tour[0] */
			rel_count++;
			return gimme_tree(root, tour, rel_count, num_gene, inner_rel);
		}
		else
		{						/* tree main part */

			if (!(new_rels = gimme_clause_joins(root, outer_rel, inner_rel)))
			{
				if (BushyPlanFlag)
				{
					new_rels = lcons(gimme_clauseless_join(outer_rel, outer_rel), NIL); /* ??? MAU */
				}
				else
					new_rels = lcons(gimme_clauseless_join(outer_rel, inner_rel), NIL);
			}

			/* process new_rel->pathlist */
			find_all_join_paths(root, new_rels);

			/* prune new_rels */
			/* MAU: is this necessary? */

			/*
			 * what's the matter if more than one new rel is left till
			 * now?
			 */

			/*
			 * joinrels in newrels with different ordering of relids are
			 * not possible
			 */
			if (length(new_rels) > 1)
				new_rels = geqo_prune_rels(new_rels);

			if (length(new_rels) > 1)
			{					/* should never be reached ... */
				elog(DEBUG, "gimme_tree: still %d relations left", length(new_rels));
			}

			/* get essential new relation */
			new_rel = (RelOptInfo *) lfirst(new_rels);
			rel_count++;

			/* process new_rel->cheapestpath, new_rel->unorderedpath */
			geqo_rel_paths(new_rel);

			/* processing of other new_rel attributes */
			if (new_rel->size <= 0)
				new_rel->size = compute_rel_size(new_rel);
			new_rel->width = compute_rel_width(new_rel);

			root->join_rel_list = lcons(new_rel, NIL);

			return gimme_tree(root, tour, rel_count, num_gene, new_rel);
		}

	}

	return (outer_rel);			/* tree finished ... */
}

/*
 * gimme-clause-joins--
 *
 * 'outer-rel' is the relation entry for the outer relation
 * 'inner-rel' is the relation entry for the inner relation
 *
 * Returns a list of new join relations.
 */

static List *
gimme_clause_joins(Query *root, RelOptInfo *outer_rel, RelOptInfo *inner_rel)
{
	List	   *join_list = NIL;
	List	   *i = NIL;
	List	   *joininfo_list = (List *) outer_rel->joininfo;

	foreach(i, joininfo_list)
	{
		JInfo	   *joininfo = (JInfo *) lfirst(i);
		RelOptInfo		   *rel = NULL;

		if (!joininfo->inactive)
		{
			List	   *other_rels = (List *) joininfo->otherrels;

			if (other_rels != NIL)
			{
				if ((length(other_rels) == 1))
				{

					if (same(other_rels, inner_rel->relids))
					{			/* look if inner_rel is it... */
						rel = init_join_rel(outer_rel, inner_rel, joininfo);
					}
				}
				else if (BushyPlanFlag)
				{				/* ?!? MAU */
					rel = init_join_rel(outer_rel, get_join_rel(root, other_rels), joininfo);
				}
				else
					rel = NULL;

				if (rel != NULL)
					join_list = lappend(join_list, rel);

			}
		}
	}

	return (join_list);
}

/*
 * gimme-clauseless-join--
 *	  Given an outer relation 'outer-rel' and an inner relation
 *	  'inner-rel', create a join relation between 'outer-rel' and 'inner-rel'
 *
 * Returns a new join relation.
 */

static RelOptInfo *
gimme_clauseless_join(RelOptInfo *outer_rel, RelOptInfo *inner_rel)
{
	return (init_join_rel(outer_rel, inner_rel, (JInfo *) NULL));
}

/*
 * init-join-rel--
 *	  Creates and initializes a new join relation.
 *
 * 'outer-rel' and 'inner-rel' are relation nodes for the relations to be
 *		joined
 * 'joininfo' is the joininfo node(join clause) containing both
 *		'outer-rel' and 'inner-rel', if any exists
 *
 * Returns the new join relation node.
 */
static RelOptInfo *
init_join_rel(RelOptInfo *outer_rel, RelOptInfo *inner_rel, JInfo *joininfo)
{
	RelOptInfo		   *joinrel = makeNode(RelOptInfo);
	List	   *joinrel_joininfo_list = NIL;
	List	   *new_outer_tlist;
	List	   *new_inner_tlist;

	/*
	 * Create a new tlist by removing irrelevant elements from both tlists
	 * of the outer and inner join relations and then merging the results
	 * together.
	 */
	new_outer_tlist =
		new_join_tlist(outer_rel->targetlist,	/* XXX 1-based attnos */
					   inner_rel->relids, 1);
	new_inner_tlist =
		new_join_tlist(inner_rel->targetlist,	/* XXX 1-based attnos */
					   outer_rel->relids,
					   length(new_outer_tlist) + 1);

	joinrel->relids = NIL;
	joinrel->indexed = false;
	joinrel->pages = 0;
	joinrel->tuples = 0;
	joinrel->width = 0;
/*	  joinrel->targetlist = NIL;*/
	joinrel->pathlist = NIL;
	joinrel->unorderedpath = (Path *) NULL;
	joinrel->cheapestpath = (Path *) NULL;
	joinrel->pruneable = true;
	joinrel->classlist = NULL;
	joinrel->relam = InvalidOid;
	joinrel->ordering = NULL;
	joinrel->clauseinfo = NIL;
	joinrel->joininfo = NULL;
	joinrel->innerjoin = NIL;
	joinrel->superrels = NIL;

	joinrel->relids = lcons(outer_rel->relids, lcons(inner_rel->relids, NIL));

	new_outer_tlist = nconc(new_outer_tlist, new_inner_tlist);
	joinrel->targetlist = new_outer_tlist;

	if (joininfo)
	{
		joinrel->clauseinfo = joininfo->jinfoclauseinfo;
		if (BushyPlanFlag)
			joininfo->inactive = true;
	}

	joinrel_joininfo_list =
		new_joininfo_list(append(outer_rel->joininfo, inner_rel->joininfo),
						intAppend(outer_rel->relids, inner_rel->relids));

	joinrel->joininfo = joinrel_joininfo_list;

	geqo_joinrel_size(joinrel, outer_rel, inner_rel);

	return (joinrel);
}

/*
 * new-join-tlist--
 *	  Builds a join relations's target list by keeping those elements that
 *	  will be in the final target list and any other elements that are still
 *	  needed for future joins.	For a target list entry to still be needed
 *	  for future joins, its 'joinlist' field must not be empty after removal
 *	  of all relids in 'other-relids'.
 *
 * 'tlist' is the target list of one of the join relations
 * 'other-relids' is a list of relids contained within the other
 *				join relation
 * 'first-resdomno' is the resdom number to use for the first created
 *				target list entry
 *
 * Returns the new target list.
 */
static List *
new_join_tlist(List *tlist,
			   List *other_relids,
			   int first_resdomno)
{
	int			resdomno = first_resdomno - 1;
	TargetEntry *xtl = NULL;
	List	   *temp_node = NIL;
	List	   *t_list = NIL;
	List	   *i = NIL;
	List	   *join_list = NIL;
	bool		in_final_tlist = false;


	foreach(i, tlist)
	{
		xtl = lfirst(i);
		in_final_tlist = (join_list == NIL);
		if (in_final_tlist)
		{
			resdomno += 1;
			temp_node =
				lcons(create_tl_element(get_expr(xtl),
										resdomno),
					  NIL);
			t_list = nconc(t_list, temp_node);
		}
	}

	return (t_list);
}

/*
 * new-joininfo-list--
 *	  Builds a join relation's joininfo list by checking for join clauses
 *	  which still need to used in future joins involving this relation.  A
 *	  join clause is still needed if there are still relations in the clause
 *	  not contained in the list of relations comprising this join relation.
 *	  New joininfo nodes are only created and added to
 *	  'current-joininfo-list' if a node for a particular join hasn't already
 *	  been created.
 *
 * 'current-joininfo-list' contains a list of those joininfo nodes that
 *		have already been built
 * 'joininfo-list' is the list of join clauses involving this relation
 * 'join-relids' is a list of relids corresponding to the relations
 *		currently being joined
 *
 * Returns a list of joininfo nodes, new and old.
 */
static List *
new_joininfo_list(List *joininfo_list, List *join_relids)
{
	List	   *current_joininfo_list = NIL;
	List	   *new_otherrels = NIL;
	JInfo	   *other_joininfo = (JInfo *) NULL;
	List	   *xjoininfo = NIL;

	foreach(xjoininfo, joininfo_list)
	{
		List	   *or;
		JInfo	   *joininfo = (JInfo *) lfirst(xjoininfo);

		new_otherrels = joininfo->otherrels;
		foreach(or, new_otherrels)
		{
			if (intMember(lfirsti(or), join_relids))
				new_otherrels = lremove((void *) lfirst(or), new_otherrels);
		}
		joininfo->otherrels = new_otherrels;
		if (new_otherrels != NIL)
		{
			other_joininfo = joininfo_member(new_otherrels,
											 current_joininfo_list);
			if (other_joininfo)
			{
				other_joininfo->jinfoclauseinfo =
					(List *) LispUnion(joininfo->jinfoclauseinfo,
									   other_joininfo->jinfoclauseinfo);
			}
			else
			{
				other_joininfo = makeNode(JInfo);

				other_joininfo->otherrels =
					joininfo->otherrels;
				other_joininfo->jinfoclauseinfo =
					joininfo->jinfoclauseinfo;
				other_joininfo->mergejoinable =
					joininfo->mergejoinable;
				other_joininfo->hashjoinable =
					joininfo->hashjoinable;
				other_joininfo->inactive = false;

				current_joininfo_list = lcons(other_joininfo,
											  current_joininfo_list);
			}
		}
	}

	return (current_joininfo_list);
}

#ifdef	NOTUSED
/*
 * add-new-joininfos--
 *	  For each new join relation, create new joininfos that
 *	  use the join relation as inner relation, and add
 *	  the new joininfos to those rel nodes that still
 *	  have joins with the join relation.
 *
 * 'joinrels' is a list of join relations.
 *
 * Modifies the joininfo field of appropriate rel nodes.
 */
static void
geqo_add_new_joininfos(Query *root, List *joinrels, List *outerrels)
{
	List	   *xjoinrel = NIL;
	List	   *xrelid = NIL;
	List	   *xrel = NIL;
	List	   *xjoininfo = NIL;

	RelOptInfo		   *rel;
	List	   *relids;

	List	   *super_rels;
	List	   *xsuper_rel = NIL;
	JInfo	   *new_joininfo;

	foreach(xjoinrel, joinrels)
	{
		RelOptInfo		   *joinrel = (RelOptInfo *) lfirst(xjoinrel);

		foreach(xrelid, joinrel->relids)
		{

			/*
			 * length(joinrel->relids) should always be greater that 1,
			 * because of *JOIN*
			 */

			/*
			 * ! BUG BUG ! Relid relid = (Relid)lfirst(xrelid); RelOptInfo *rel =
			 * get_join_rel(root, relid);
			 */

			/*
			 * if ( (root->join_rel_list) != NIL ) { rel =
			 * get_join_rel(root, xrelid); } else { rel =
			 * get_base_rel(root, lfirsti(xrelid)); }
			 */

			/* NOTE: STILL BUGGY FOR CLAUSE-JOINS: */

			/*
			 * relids = lconsi(lfirsti(xrelid), NIL); rel =
			 * rel_member(relids, outerrels);
			 */

			relids = lconsi(lfirsti(xrelid), NIL);
			rel = rel_member(relids, root->base_rel_list);

			add_superrels(rel, joinrel);
		}
	}
	foreach(xjoinrel, joinrels)
	{
		RelOptInfo		   *joinrel = (RelOptInfo *) lfirst(xjoinrel);

		foreach(xjoininfo, joinrel->joininfo)
		{
			JInfo	   *joininfo = (JInfo *) lfirst(xjoininfo);
			List	   *other_rels = joininfo->otherrels;
			List	   *clause_info = joininfo->jinfoclauseinfo;
			bool		mergejoinable = joininfo->mergejoinable;
			bool		hashjoinable = joininfo->hashjoinable;

			foreach(xrelid, other_rels)
			{

				/*
				 * ! BUG BUG ! Relid relid = (Relid)lfirst(xrelid); RelOptInfo
				 * *rel = get_join_rel(root, relid);
				 */

				/*
				 * if ( (root->join_rel_list) != NIL ) { rel =
				 * get_join_rel(root, xrelid); } else { rel =
				 * get_base_rel(root, lfirsti(xrelid)); }
				 */

				/* NOTE: STILL BUGGY FOR CLAUSE-JOINS: */

				/*
				 * relids = lconsi(lfirsti(xrelid), NIL); rel =
				 * rel_member(relids, outerrels);
				 */

				relids = lconsi(lfirsti(xrelid), NIL);
				rel = rel_member(relids, root->base_rel_list);

				super_rels = rel->superrels;
				new_joininfo = makeNode(JInfo);

				new_joininfo->otherrels = joinrel->relids;
				new_joininfo->jinfoclauseinfo = clause_info;
				new_joininfo->mergejoinable = mergejoinable;
				new_joininfo->hashjoinable = hashjoinable;
				new_joininfo->inactive = false;
				rel->joininfo =
					lappend(rel->joininfo, new_joininfo);

				foreach(xsuper_rel, super_rels)
				{
					RelOptInfo		   *super_rel = (RelOptInfo *) lfirst(xsuper_rel);

					if (nonoverlap_rels(super_rel, joinrel))
					{
						List	   *new_relids = super_rel->relids;
						JInfo	   *other_joininfo =
						joininfo_member(new_relids,
										joinrel->joininfo);

						if (other_joininfo)
						{
							other_joininfo->jinfoclauseinfo =
								(List *) LispUnion(clause_info,
										other_joininfo->jinfoclauseinfo);
						}
						else
						{
							JInfo	   *new_joininfo = makeNode(JInfo);

							new_joininfo->otherrels = new_relids;
							new_joininfo->jinfoclauseinfo = clause_info;
							new_joininfo->mergejoinable = mergejoinable;
							new_joininfo->hashjoinable = hashjoinable;
							new_joininfo->inactive = false;
							joinrel->joininfo =
								lappend(joinrel->joininfo,
										new_joininfo);
						}
					}
				}
			}
		}
	}
	foreach(xrel, outerrels)
	{
		rel = (RelOptInfo *) lfirst(xrel);
		rel->superrels = NIL;
	}
}

/*
 * final-join-rels--
 *	   Find the join relation that includes all the original
 *	   relations, i.e. the final join result.
 *
 * 'join-rel-list' is a list of join relations.
 *
 * Returns the list of final join relations.
 */
static List *
geqo_final_join_rels(List *join_rel_list)
{
	List	   *xrel = NIL;
	List	   *temp = NIL;
	List	   *t_list = NIL;

	/*
	 * find the relations that has no further joins, i.e., its joininfos
	 * all have otherrels nil.
	 */
	foreach(xrel, join_rel_list)
	{
		RelOptInfo		   *rel = (RelOptInfo *) lfirst(xrel);
		List	   *xjoininfo = NIL;
		bool		final = true;

		foreach(xjoininfo, rel->joininfo)
		{
			JInfo	   *joininfo = (JInfo *) lfirst(xjoininfo);

			if (joininfo->otherrels != NIL)
			{
				final = false;
				break;
			}
		}
		if (final)
		{
			temp = lcons(rel, NIL);
			t_list = nconc(t_list, temp);
		}
	}

	return (t_list);
}

/*
 * add_superrels--
 *	  add rel to the temporary property list superrels.
 *
 * 'rel' a rel node
 * 'super-rel' rel node of a join relation that includes rel
 *
 * Modifies the superrels field of rel
 */
static void
add_superrels(RelOptInfo *rel, RelOptInfo *super_rel)
{
	rel->superrels = lappend(rel->superrels, super_rel);
}

/*
 * nonoverlap-rels--
 *	  test if two join relations overlap, i.e., includes the same
 *	  relation.
 *
 * 'rel1' and 'rel2' are two join relations
 *
 * Returns non-nil if rel1 and rel2 do not overlap.
 */
static bool
nonoverlap_rels(RelOptInfo *rel1, RelOptInfo *rel2)
{
	return (nonoverlap_sets(rel1->relids, rel2->relids));
}

static bool
nonoverlap_sets(List *s1, List *s2)
{
	List	   *x = NIL;

	foreach(x, s1)
	{
		int			e = lfirsti(x);

		if (intMember(e, s2))
			return (false);
	}
	return (true);
}

#endif							/* NOTUSED */

/*
 * geqo_joinrel_size--
 *	  compute estimate for join relation tuples, even for
 *	  long join queries; so get logarithm of size when MAXINT overflow;
 */
static void
geqo_joinrel_size(RelOptInfo *joinrel, RelOptInfo *outer_rel, RelOptInfo *inner_rel)
{
	Cost		temp;
	int			ntuples;

	temp = (Cost) inner_rel->tuples * (Cost) outer_rel->tuples; /* cartesian product */

	if (joinrel->clauseinfo)
		temp = temp * product_selec(joinrel->clauseinfo);

	if (temp >= (MAXINT - 1))
		ntuples = ceil(geqo_log((double) temp, (double) GEQO_LOG_BASE));
	else
		ntuples = ceil((double) temp);

	if (ntuples < 1)
		ntuples = 1;			/* make the best case 1 instead of 0 */

	joinrel->tuples = ntuples;
}

double
geqo_log(double x, double b)
{
	return (log(x) / log(b));
}

static RelOptInfo *
geqo_nth(int stop, List *rels)
{
	List	   *r;
	int			i = 1;

	foreach(r, rels)
	{
		if (i == stop)
			return lfirst(r);
		i++;
	}
	elog(ERROR, "geqo_nth: Internal error - ran off end of list");
	return NULL;				/* to keep compiler happy */
}