createplan.c

/*-------------------------------------------------------------------------
 *
 * createplan.c--
 *	  Routines to create the desired plan for processing a query
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.25 1998/02/10 04:01:09 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include <string.h>
#include <sys/types.h>

#include "postgres.h"

#include <utils/syscache.h>
#include <catalog/pg_index.h>

#include "nodes/execnodes.h"
#include "nodes/plannodes.h"
#include "nodes/relation.h"
#include "nodes/primnodes.h"
#include "nodes/nodeFuncs.h"

#include "nodes/makefuncs.h"

#include "utils/lsyscache.h"
#include "utils/palloc.h"
#include "utils/builtins.h"

#include "optimizer/clauseinfo.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
#include "optimizer/planner.h"
#include "optimizer/xfunc.h"
#include "optimizer/internal.h"


#define TEMP_SORT		1
#define TEMP_MATERIAL	2

static List *switch_outer(List *clauses);
static Scan *create_scan_node(Path *best_path, List *tlist);
static Join *create_join_node(JoinPath *best_path, List *tlist);
static SeqScan *create_seqscan_node(Path *best_path, List *tlist,
					List *scan_clauses);
static IndexScan *create_indexscan_node(IndexPath *best_path, List *tlist,
					  List *scan_clauses);
static NestLoop *create_nestloop_node(JoinPath *best_path, List *tlist,
					 List *clauses, Plan *outer_node, List *outer_tlist,
					 Plan *inner_node, List *inner_tlist);
static MergeJoin *create_mergejoin_node(MergePath *best_path, List *tlist,
					  List *clauses, Plan *outer_node, List *outer_tlist,
					  Plan *inner_node, List *inner_tlist);
static HashJoin *create_hashjoin_node(HashPath *best_path, List *tlist,
					 List *clauses, Plan *outer_node, List *outer_tlist,
					 Plan *inner_node, List *inner_tlist);
static Node *fix_indxqual_references(Node *clause, Path *index_path);
static Temp *make_temp(List *tlist, List *keys, Oid *operators,
		  Plan *plan_node, int temptype);
static IndexScan *make_indexscan(List *qptlist, List *qpqual, Index scanrelid,
			   List *indxid, List *indxqual, Cost cost);
static NestLoop *make_nestloop(List *qptlist, List *qpqual, Plan *lefttree,
			  Plan *righttree);
static HashJoin *make_hashjoin(List *tlist, List *qpqual,
			  List *hashclauses, Plan *lefttree, Plan *righttree);
static Hash *make_hash(List *tlist, Var *hashkey, Plan *lefttree);
static MergeJoin *make_mergesort(List *tlist, List *qpqual,
			   List *mergeclauses, Oid opcode, Oid *rightorder,
			   Oid *leftorder, Plan *righttree, Plan *lefttree);
static Material *make_material(List *tlist, Oid tempid, Plan *lefttree,
			  int keycount);

/*
 * create_plan--
 *	  Creates the access plan for a query by tracing backwards through the
 *	  desired chain of pathnodes, starting at the node 'best-path'.  For
 *	  every pathnode found:
 *	  (1) Create a corresponding plan node containing appropriate id,
 *		  target list, and qualification information.
 *	  (2) Modify ALL clauses so that attributes are referenced using
 *		  relative values.
 *	  (3) Target lists are not modified, but will be in another routine.
 *
 *	  best-path is the best access path
 *
 *	  Returns the optimal(?) access plan.
 */
Plan	   *
create_plan(Path *best_path)
{
	List	   *tlist;
	Plan	   *plan_node = (Plan *) NULL;
	Rel		   *parent_rel;
	int			size;
	int			width;
	int			pages;
	int			tuples;

	parent_rel = best_path->parent;
	tlist = get_actual_tlist(parent_rel->targetlist);
	size = parent_rel->size;
	width = parent_rel->width;
	pages = parent_rel->pages;
	tuples = parent_rel->tuples;

	switch (best_path->pathtype)
	{
		case T_IndexScan:
		case T_SeqScan:
			plan_node = (Plan *) create_scan_node(best_path, tlist);
			break;
		case T_HashJoin:
		case T_MergeJoin:
		case T_NestLoop:
			plan_node = (Plan *) create_join_node((JoinPath *) best_path, tlist);
			break;
		default:
			/* do nothing */
			break;
	}

	plan_node->plan_size = size;
	plan_node->plan_width = width;
	if (pages == 0)
		pages = 1;
	plan_node->plan_tupperpage = tuples / pages;

#if 0							/* fix xfunc */
	/* sort clauses by cost/(1-selectivity) -- JMH 2/26/92 */
	if (XfuncMode != XFUNC_OFF)
	{
		set_qpqual((Plan) plan_node,
				   lisp_qsort(get_qpqual((Plan) plan_node),
							  xfunc_clause_compare));
		if (XfuncMode != XFUNC_NOR)
			/* sort the disjuncts within each clause by cost -- JMH 3/4/92 */
			xfunc_disjunct_sort(plan_node->qpqual);
	}
#endif

	return (plan_node);
}

/*
 * create_scan_node--
 *	 Create a scan path for the parent relation of 'best-path'.
 *
 *	 tlist is the targetlist for the base relation scanned by 'best-path'
 *
 *	 Returns the scan node.
 */
static Scan *
create_scan_node(Path *best_path, List *tlist)
{

	Scan	   *node = NULL;
	List	   *scan_clauses;

	/*
	 * Extract the relevant clauses from the parent relation and replace
	 * the operator OIDs with the corresponding regproc ids.
	 *
	 * now that local predicate clauses are copied into paths in
	 * find_rel_paths() and then (possibly) pulled up in
	 * xfunc_trypullup(), we get the relevant clauses from the path
	 * itself, not its parent relation.   --- JMH, 6/15/92
	 */
	scan_clauses = fix_opids(get_actual_clauses(best_path->locclauseinfo));

	switch (best_path->pathtype)
	{
		case T_SeqScan:
			node = (Scan *) create_seqscan_node(best_path, tlist, scan_clauses);
			break;

		case T_IndexScan:
			node = (Scan *) create_indexscan_node((IndexPath *) best_path,
												  tlist,
												  scan_clauses);
			break;

		default:
			elog(ERROR, "create_scan_node: unknown node type",
				 best_path->pathtype);
			break;
	}

	return node;
}

/*
 * create_join_node --
 *	  Create a join path for 'best-path' and(recursively) paths for its
 *	  inner and outer paths.
 *
 *	  'tlist' is the targetlist for the join relation corresponding to
 *		'best-path'
 *
 *	  Returns the join node.
 */
static Join *
create_join_node(JoinPath *best_path, List *tlist)
{
	Plan	   *outer_node;
	List	   *outer_tlist;
	Plan	   *inner_node;
	List	   *inner_tlist;
	List	   *clauses;
	Join	   *retval = NULL;

	outer_node = create_plan((Path *) best_path->outerjoinpath);
	outer_tlist = outer_node->targetlist;

	inner_node = create_plan((Path *) best_path->innerjoinpath);
	inner_tlist = inner_node->targetlist;

	clauses = get_actual_clauses(best_path->pathclauseinfo);

	switch (best_path->path.pathtype)
	{
		case T_MergeJoin:
			retval = (Join *) create_mergejoin_node((MergePath *) best_path,
													tlist,
													clauses,
													outer_node,
													outer_tlist,
													inner_node,
													inner_tlist);
			break;
		case T_HashJoin:
			retval = (Join *) create_hashjoin_node((HashPath *) best_path,
												   tlist,
												   clauses,
												   outer_node,
												   outer_tlist,
												   inner_node,
												   inner_tlist);
			break;
		case T_NestLoop:
			retval = (Join *) create_nestloop_node((JoinPath *) best_path,
												   tlist,
												   clauses,
												   outer_node,
												   outer_tlist,
												   inner_node,
												   inner_tlist);
			break;
		default:
			/* do nothing */
			elog(ERROR, "create_join_node: unknown node type",
				 best_path->path.pathtype);
	}

#if 0

	/*
	 * * Expensive function pullups may have pulled local predicates *
	 * into this path node.  Put them in the qpqual of the plan node. * --
	 * JMH, 6/15/92
	 */
	if (get_locclauseinfo(best_path) != NIL)
		set_qpqual((Plan) retval,
				   nconc(get_qpqual((Plan) retval),
						 fix_opids(get_actual_clauses
								   (get_locclauseinfo(best_path)))));
#endif

	return (retval);
}

/*****************************************************************************
 *
 *	BASE-RELATION SCAN METHODS
 *
 *****************************************************************************/


/*
 * create_seqscan_node--
 *	 Returns a seqscan node for the base relation scanned by 'best-path'
 *	 with restriction clauses 'scan-clauses' and targetlist 'tlist'.
 */
static SeqScan *
create_seqscan_node(Path *best_path, List *tlist, List *scan_clauses)
{
	SeqScan    *scan_node = (SeqScan *) NULL;
	Index		scan_relid = -1;
	List	   *temp;

	temp = best_path->parent->relids;
	if (temp == NULL)
		elog(ERROR, "scanrelid is empty");
	else
		scan_relid = (Index) lfirsti(temp);		/* ??? who takes care of
												 * lnext? - ay */
	scan_node = make_seqscan(tlist,
							 scan_clauses,
							 scan_relid,
							 (Plan *) NULL);

	scan_node->plan.cost = best_path->path_cost;

	return (scan_node);
}

/*
 * create_indexscan_node--
 *	  Returns a indexscan node for the base relation scanned by 'best-path'
 *	  with restriction clauses 'scan-clauses' and targetlist 'tlist'.
 */
static IndexScan *
create_indexscan_node(IndexPath *best_path,
					  List *tlist,
					  List *scan_clauses)
{

	/*
	 * Extract the(first if conjunct, only if disjunct) clause from the
	 * clauseinfo list.
	 */
	Expr	   *index_clause = (Expr *) NULL;
	List	   *indxqual = NIL;
	List	   *qpqual = NIL;
	List	   *fixed_indxqual = NIL;
	List	   *ixid;
	IndexScan  *scan_node = (IndexScan *) NULL;
	bool		lossy = FALSE;
	HeapTuple	indexTuple;
	IndexTupleForm index;

	/*
	 * If an 'or' clause is to be used with this index, the indxqual field
	 * will contain a list of the 'or' clause arguments, e.g., the
	 * clause(OR a b c) will generate: ((a) (b) (c)).  Otherwise, the
	 * indxqual will simply contain one conjunctive qualification: ((a)).
	 */
	if (best_path->indexqual != NULL)
		/* added call to fix_opids, JMH 6/23/92 */
		index_clause = (Expr *)
			lfirst(fix_opids(get_actual_clauses(best_path->indexqual)));

	if (or_clause((Node *) index_clause))
	{
		List	   *temp = NIL;

		foreach(temp, index_clause->args)
			indxqual = lappend(indxqual, lcons(lfirst(temp), NIL));
	}
	else
	{
		indxqual = lcons(get_actual_clauses(best_path->indexqual),
						 NIL);
	}

	/* check and see if any indices are lossy */
	foreach(ixid, best_path->indexid)
	{
		indexTuple = SearchSysCacheTuple(INDEXRELID,
										 ObjectIdGetDatum(lfirsti(ixid)),
										 0, 0, 0);
		if (!HeapTupleIsValid(indexTuple))
			elog(ERROR, "create_plan: index %d not found",
				 lfirsti(ixid));
		index = (IndexTupleForm) GETSTRUCT(indexTuple);
		if (index->indislossy)
			lossy = TRUE;
	}


	/*
	 * The qpqual field contains all restrictions not automatically
	 * handled by the index.  Note that for non-lossy indices, the
	 * predicates in the indxqual are handled by the index, while for
	 * lossy indices the indxqual predicates need to be double-checked
	 * after the index fetches the best-guess tuples.
	 */
	if (or_clause((Node *) index_clause))
	{
		qpqual = set_difference(scan_clauses,
								lcons(index_clause, NIL));

		if (lossy)
			qpqual = nconc(qpqual,
						   lcons((List *) copyObject(index_clause), NIL));
	}
	else
	{
		qpqual = set_difference(scan_clauses, lfirst(indxqual));
		if (lossy)
			qpqual = nconc(qpqual,
						   (List *) copyObject(lfirst(indxqual)));
	}

	fixed_indxqual =
		(List *) fix_indxqual_references((Node *) indxqual, (Path *) best_path);

	scan_node =
		make_indexscan(tlist,
					   qpqual,
					   lfirsti(best_path->path.parent->relids),
					   best_path->indexid,
					   fixed_indxqual,
					   best_path->path.path_cost);

	return (scan_node);
}

/*****************************************************************************
 *
 *	JOIN METHODS
 *
 *****************************************************************************/

static NestLoop *
create_nestloop_node(JoinPath *best_path,
					 List *tlist,
					 List *clauses,
					 Plan *outer_node,
					 List *outer_tlist,
					 Plan *inner_node,
					 List *inner_tlist)
{
	NestLoop   *join_node = (NestLoop *) NULL;

	if (IsA(inner_node, IndexScan))
	{

		/*
		 * An index is being used to reduce the number of tuples scanned
		 * in the inner relation. There will never be more than one index
		 * used in the inner scan path, so we need only consider the first
		 * set of qualifications in indxqual.
		 *
		 * But there may be more than one clauses in this "first set" in the
		 * case of multi-column indices. - vadim 03/18/97
		 */

		List	   *inner_indxqual = lfirst(((IndexScan *) inner_node)->indxqual);
		List	   *inner_qual;
		bool		found = false;

		foreach(inner_qual, inner_indxqual)
		{
			if (!qual_clause_p((Node *) lfirst(inner_qual)))
			{
				found = true;
				break;
			}
		}

		/*
		 * If we have in fact found a join index qualification, remove
		 * these index clauses from the nestloop's join clauses and reset
		 * the inner(index) scan's qualification so that the var nodes
		 * refer to the proper outer join relation attributes.
		 *
		 * XXX Re-moving index clauses doesn't work properly: 1.
		 * fix_indxqual_references may change varattno-s in
		 * inner_indxqual; 2. clauses may be commuted I havn't time to fix
		 * it at the moment.   - vadim 04/24/97
		 */
		if (found)
		{
			List	   *new_inner_qual = NIL;

			clauses = set_difference(clauses, inner_indxqual);	/* XXX */
			new_inner_qual =
				index_outerjoin_references(inner_indxqual,
										   outer_node->targetlist,
									   ((Scan *) inner_node)->scanrelid);
			((IndexScan *) inner_node)->indxqual =
				lcons(new_inner_qual, NIL);
		}
	}
	else if (IsA_Join(inner_node))
	{
		inner_node = (Plan *) make_temp(inner_tlist,
										NIL,
										NULL,
										inner_node,
										TEMP_MATERIAL);
	}

	join_node = make_nestloop(tlist,
							  join_references(clauses,
											  outer_tlist,
											  inner_tlist),
							  outer_node,
							  inner_node);

	join_node->join.cost = best_path->path.path_cost;

	return (join_node);
}

static MergeJoin *
create_mergejoin_node(MergePath *best_path,
					  List *tlist,
					  List *clauses,
					  Plan *outer_node,
					  List *outer_tlist,
					  Plan *inner_node,
					  List *inner_tlist)
{
	List	   *qpqual,
			   *mergeclauses;
	RegProcedure opcode;
	Oid		   *outer_order,
			   *inner_order;
	MergeJoin  *join_node;


	/*
	 * Separate the mergeclauses from the other join qualification clauses
	 * and set those clauses to contain references to lower attributes.
	 */
	qpqual = join_references(set_difference(clauses,
											best_path->path_mergeclauses),
							 outer_tlist,
							 inner_tlist);

	/*
	 * Now set the references in the mergeclauses and rearrange them so
	 * that the outer variable is always on the left.
	 */
	mergeclauses = switch_outer(join_references(best_path->path_mergeclauses,
												outer_tlist,
												inner_tlist));

	opcode =
		get_opcode((best_path->jpath.path.p_ordering.ord.merge)->join_operator);

	outer_order = (Oid *) palloc(sizeof(Oid) * 2);
	outer_order[0] =
		(best_path->jpath.path.p_ordering.ord.merge)->left_operator;
	outer_order[1] = 0;

	inner_order = (Oid *) palloc(sizeof(Oid) * 2);
	inner_order[0] =
		(best_path->jpath.path.p_ordering.ord.merge)->right_operator;
	inner_order[1] = 0;

	/*
	 * Create explicit sort paths for the outer and inner join paths if
	 * necessary.  The sort cost was already accounted for in the path.
	 */
	if (best_path->outersortkeys)
	{
		Temp	   *sorted_outer_node = make_temp(outer_tlist,
												best_path->outersortkeys,
												  outer_order,
												  outer_node,
												  TEMP_SORT);

		sorted_outer_node->plan.cost = outer_node->cost;
		outer_node = (Plan *) sorted_outer_node;
	}

	if (best_path->innersortkeys)
	{
		Temp	   *sorted_inner_node = make_temp(inner_tlist,
												best_path->innersortkeys,
												  inner_order,
												  inner_node,
												  TEMP_SORT);

		sorted_inner_node->plan.cost = outer_node->cost;
		inner_node = (Plan *) sorted_inner_node;
	}

	join_node = make_mergesort(tlist,
							   qpqual,
							   mergeclauses,
							   opcode,
							   inner_order,
							   outer_order,
							   inner_node,
							   outer_node);

	join_node->join.cost = best_path->jpath.path.path_cost;

	return (join_node);
}

/*
 * create_hashjoin_node--						XXX HASH
 *
 *	  Returns a new hashjoin node.
 *
 *	  XXX hash join ops are totally bogus -- how the hell do we choose
 *		these??  at runtime?  what about a hash index?
 */
static HashJoin *
create_hashjoin_node(HashPath *best_path,
					 List *tlist,
					 List *clauses,
					 Plan *outer_node,
					 List *outer_tlist,
					 Plan *inner_node,
					 List *inner_tlist)
{
	List	   *qpqual;
	List	   *hashclauses;
	HashJoin   *join_node;
	Hash	   *hash_node;
	Var		   *innerhashkey;

	/*
	 * Separate the hashclauses from the other join qualification clauses
	 * and set those clauses to contain references to lower attributes.
	 */
	qpqual =
		join_references(set_difference(clauses,
									   best_path->path_hashclauses),
						outer_tlist,
						inner_tlist);

	/*
	 * Now set the references in the hashclauses and rearrange them so
	 * that the outer variable is always on the left.
	 */
	hashclauses =
		switch_outer(join_references(best_path->path_hashclauses,
									 outer_tlist,
									 inner_tlist));

	innerhashkey = get_rightop(lfirst(hashclauses));

	hash_node = make_hash(inner_tlist, innerhashkey, inner_node);
	join_node = make_hashjoin(tlist,
							  qpqual,
							  hashclauses,
							  outer_node,
							  (Plan *) hash_node);
	join_node->join.cost = best_path->jpath.path.path_cost;

	return (join_node);
}


/*****************************************************************************
 *
 *	SUPPORTING ROUTINES
 *
 *****************************************************************************/

static Node *
fix_indxqual_references(Node *clause, Path *index_path)
{
	Node	   *newclause;

	if (IsA(clause, Var))
	{
		if (lfirsti(index_path->parent->relids) == ((Var *) clause)->varno)
		{
			int			pos = 0;
			int			varatt = ((Var *) clause)->varattno;
			int		   *indexkeys = ((IndexPath *) index_path)->indexkeys;

			if (indexkeys)
			{
				while (indexkeys[pos] != 0)
				{
					if (varatt == indexkeys[pos])
					{
						break;
					}
					pos++;
				}
			}
			newclause = copyObject((Node *) clause);
			((Var *) newclause)->varattno = pos + 1;
			return (newclause);
		}
		else
		{
			return (clause);
		}
	}
	else if (IsA(clause, Const))
	{
		return (clause);
#ifdef INDEXSCAN_PATCH
	}
	else if (IsA(clause, Param))
	{
		/* Function parameter used as index scan arg.  DZ - 27-8-1996 */
		return (clause);
#endif
	}
	else if (is_opclause(clause) &&
			 is_funcclause((Node *) get_leftop((Expr *) clause)) &&
	((Func *) ((Expr *) get_leftop((Expr *) clause))->oper)->funcisindex)
	{
		Var		   *newvar =
		makeVar((Index) lfirsti(index_path->parent->relids),
				1,				/* func indices have one key */
				((Func *) ((Expr *) clause)->oper)->functype,
				-1,
				0,
				(Index) lfirsti(index_path->parent->relids),
				0);

		return
			((Node *) make_opclause((Oper *) ((Expr *) clause)->oper,
									newvar,
									get_rightop((Expr *) clause)));

	}
	else if (IsA(clause, Expr))
	{
		Expr	   *expr = (Expr *) clause;
		List	   *new_subclauses = NIL;
		Node	   *subclause = NULL;
		List	   *i = NIL;

		foreach(i, expr->args)
		{
			subclause = lfirst(i);
			if (subclause)
				new_subclauses =
					lappend(new_subclauses,
							fix_indxqual_references(subclause,
													index_path));

		}

		/*
		 * XXX new_subclauses should be a list of the form: ( (var var)
		 * (var const) ...) ?
		 */
		if (new_subclauses)
		{
			return (Node *)
				make_clause(expr->opType, expr->oper, new_subclauses);
		}
		else
		{
			return (clause);
		}
	}
	else
	{
		List	   *oldclauses = (List *) clause;
		List	   *new_subclauses = NIL;
		Node	   *subclause = NULL;
		List	   *i = NIL;

		foreach(i, oldclauses)
		{
			subclause = lfirst(i);
			if (subclause)
				new_subclauses =
					lappend(new_subclauses,
							fix_indxqual_references(subclause,
													index_path));

		}

		/*
		 * XXX new_subclauses should be a list of the form: ( (var var)
		 * (var const) ...) ?
		 */
		if (new_subclauses)
		{
			return (Node *) new_subclauses;
		}
		else
		{
			return (clause);
		}
	}
}


/*
 * switch_outer--
 *	  Given a list of merge clauses, rearranges the elements within the
 *	  clauses so the outer join variable is on the left and the inner is on
 *	  the right.
 *
 *	  Returns the rearranged list ?
 *
 *	  XXX Shouldn't the operator be commuted?!
 */
static List *
switch_outer(List *clauses)
{
	List	   *t_list = NIL;
	Expr	   *temp = NULL;
	List	   *i = NIL;
	Expr	   *clause;
	Node	   *op;

	foreach(i, clauses)
	{
		clause = lfirst(i);
		op = (Node *) get_rightop(clause);
		if (IsA(op, ArrayRef))
			op = ((ArrayRef *) op)->refexpr;
		Assert(IsA(op, Var));
		if (var_is_outer((Var *) op))
		{
			temp = make_clause(clause->opType, clause->oper,
							   lcons(get_rightop(clause),
									 lcons(get_leftop(clause),
										   NIL)));
			t_list = lappend(t_list, temp);
		}
		else
			t_list = lappend(t_list, clause);
	}
	return (t_list);
}

/*
 * set-temp-tlist-operators--
 *	  Sets the key and keyop fields of resdom nodes in a target list.
 *
 *	  'tlist' is the target list
 *	  'pathkeys' is a list of N keys in the form((key1) (key2)...(keyn)),
 *				corresponding to vars in the target list that are to
 *				be sorted or hashed
 *	  'operators' is the corresponding list of N sort or hash operators
 *	  'keyno' is the first key number
 *	  XXX - keyno ? doesn't exist - jeff
 *
 *	  Returns the modified target list.
 */
static List *
set_temp_tlist_operators(List *tlist, List *pathkeys, Oid *operators)
{
	Node	   *keys = NULL;
	int			keyno = 1;
	Resdom	   *resdom = (Resdom *) NULL;
	List	   *i = NIL;

	foreach(i, pathkeys)
	{
		keys = lfirst((List *) lfirst(i));
		resdom = tlist_member((Var *) keys, tlist);
		if (resdom)
		{

			/*
			 * Order the resdom keys and replace the operator OID for each
			 * key with the regproc OID.
			 *
			 * XXX Note that the optimizer only generates merge joins with 1
			 * operator (see create_mergejoin_node)  - ay 2/95
			 */
			resdom->reskey = keyno;
			resdom->reskeyop = get_opcode(operators[0]);
		}
		keyno += 1;
	}
	return (tlist);
}

/*****************************************************************************
 *
 *
 *****************************************************************************/

/*
 * make_temp--
 *	  Create plan nodes to sort or materialize relations into temporaries. The
 *	  result returned for a sort will look like (SEQSCAN(SORT(plan-node)))
 *	  or (SEQSCAN(MATERIAL(plan-node)))
 *
 *	  'tlist' is the target list of the scan to be sorted or hashed
 *	  'keys' is the list of keys which the sort or hash will be done on
 *	  'operators' is the operators with which the sort or hash is to be done
 *		(a list of operator OIDs)
 *	  'plan-node' is the node which yields tuples for the sort
 *	  'temptype' indicates which operation(sort or hash) to perform
 */
static Temp *
make_temp(List *tlist,
		  List *keys,
		  Oid *operators,
		  Plan *plan_node,
		  int temptype)
{
	List	   *temp_tlist;
	Temp	   *retval = NULL;

	/* Create a new target list for the temporary, with keys set. */
	temp_tlist = set_temp_tlist_operators(new_unsorted_tlist(tlist),
										  keys,
										  operators);
	switch (temptype)
	{
		case TEMP_SORT:
			retval = (Temp *) make_seqscan(tlist,
										   NIL,
										   _TEMP_RELATION_ID_,
										   (Plan *) make_sort(temp_tlist,
													  _TEMP_RELATION_ID_,
															  plan_node,
														  length(keys)));
			break;

		case TEMP_MATERIAL:
			retval = (Temp *) make_seqscan(tlist,
										   NIL,
										   _TEMP_RELATION_ID_,
									   (Plan *) make_material(temp_tlist,
													  _TEMP_RELATION_ID_,
															  plan_node,
														  length(keys)));
			break;

		default:
			elog(ERROR, "make_temp: unknown temp type %d", temptype);

	}
	return (retval);
}


SeqScan    *
make_seqscan(List *qptlist,
			 List *qpqual,
			 Index scanrelid,
			 Plan *lefttree)
{
	SeqScan    *node = makeNode(SeqScan);
	Plan	   *plan = &node->plan;

    plan->cost = (lefttree ? lefttree->cost : 0);
	plan->state = (EState *) NULL;
	plan->targetlist = qptlist;
	plan->qual = qpqual;
	plan->lefttree = lefttree;
	plan->righttree = NULL;
	node->scanrelid = scanrelid;
	node->scanstate = (CommonScanState *) NULL;

	return (node);
}

static IndexScan *
make_indexscan(List *qptlist,
			   List *qpqual,
			   Index scanrelid,
			   List *indxid,
			   List *indxqual,
			   Cost  cost)
{
	IndexScan  *node = makeNode(IndexScan);
	Plan	   *plan = &node->scan.plan;

	plan->cost = cost;
	plan->state = (EState *) NULL;
	plan->targetlist = qptlist;
	plan->qual = qpqual;
	plan->lefttree = NULL;
	plan->righttree = NULL;
	node->scan.scanrelid = scanrelid;
	node->indxid = indxid;
	node->indxqual = indxqual;
	node->scan.scanstate = (CommonScanState *) NULL;

	return (node);
}


static NestLoop *
make_nestloop(List *qptlist,
			  List *qpqual,
			  Plan *lefttree,
			  Plan *righttree)
{
	NestLoop   *node = makeNode(NestLoop);
	Plan	   *plan = &node->join;

    plan->cost = (lefttree ? lefttree->cost : 0) +
		 (righttree ? righttree->cost : 0);
	plan->state = (EState *) NULL;
	plan->targetlist = qptlist;
	plan->qual = qpqual;
	plan->lefttree = lefttree;
	plan->righttree = righttree;
	node->nlstate = (NestLoopState *) NULL;

	return (node);
}

static HashJoin *
make_hashjoin(List *tlist,
			  List *qpqual,
			  List *hashclauses,
			  Plan *lefttree,
			  Plan *righttree)
{
	HashJoin   *node = makeNode(HashJoin);
	Plan	   *plan = &node->join;

    plan->cost = (lefttree ? lefttree->cost : 0) +
		 (righttree ? righttree->cost : 0);
	plan->cost = 0.0;
	plan->state = (EState *) NULL;
	plan->targetlist = tlist;
	plan->qual = qpqual;
	plan->lefttree = lefttree;
	plan->righttree = righttree;
	node->hashclauses = hashclauses;
	node->hashjointable = NULL;
	node->hashjointablekey = 0;
	node->hashjointablesize = 0;
	node->hashdone = false;

	return (node);
}

static Hash *
make_hash(List *tlist, Var *hashkey, Plan *lefttree)
{
	Hash	   *node = makeNode(Hash);
	Plan	   *plan = &node->plan;

    plan->cost = (lefttree ? lefttree->cost : 0);
	plan->cost = 0.0;
	plan->state = (EState *) NULL;
	plan->targetlist = tlist;
	plan->qual = NULL;
	plan->lefttree = lefttree;
	plan->righttree = NULL;
	node->hashkey = hashkey;
	node->hashtable = NULL;
	node->hashtablekey = 0;
	node->hashtablesize = 0;

	return (node);
}

static MergeJoin *
make_mergesort(List *tlist,
			   List *qpqual,
			   List *mergeclauses,
			   Oid opcode,
			   Oid *rightorder,
			   Oid *leftorder,
			   Plan *righttree,
			   Plan *lefttree)
{
	MergeJoin  *node = makeNode(MergeJoin);
	Plan	   *plan = &node->join;

    plan->cost = (lefttree ? lefttree->cost : 0) +
		 (righttree ? righttree->cost : 0);
	plan->state = (EState *) NULL;
	plan->targetlist = tlist;
	plan->qual = qpqual;
	plan->lefttree = lefttree;
	plan->righttree = righttree;
	node->mergeclauses = mergeclauses;
	node->mergesortop = opcode;
	node->mergerightorder = rightorder;
	node->mergeleftorder = leftorder;

	return (node);
}

Sort	   *
make_sort(List *tlist, Oid tempid, Plan *lefttree, int keycount)
{
	Sort	   *node = makeNode(Sort);
	Plan	   *plan = &node->plan;

    plan->cost = (lefttree ? lefttree->cost : 0);
	plan->state = (EState *) NULL;
	plan->targetlist = tlist;
	plan->qual = NIL;
	plan->lefttree = lefttree;
	plan->righttree = NULL;
	node->tempid = tempid;
	node->keycount = keycount;

	return (node);
}

static Material *
make_material(List *tlist,
			  Oid tempid,
			  Plan *lefttree,
			  int keycount)
{
	Material   *node = makeNode(Material);
	Plan	   *plan = &node->plan;

    plan->cost = (lefttree ? lefttree->cost : 0);
	plan->state = (EState *) NULL;
	plan->targetlist = tlist;
	plan->qual = NIL;
	plan->lefttree = lefttree;
	plan->righttree = NULL;
	node->tempid = tempid;
	node->keycount = keycount;

	return (node);
}

Agg		   *
make_agg(List *tlist, Plan *lefttree)
{
	Agg		   *node = makeNode(Agg);

    node->plan.cost = (lefttree ? lefttree->cost : 0);
	node->plan.state = (EState *) NULL;
	node->plan.qual = NULL;
	node->plan.targetlist = tlist;
	node->plan.lefttree = lefttree;
	node->plan.righttree = (Plan *) NULL;
	node->aggs = NIL;

	return (node);
}

Group	   *
make_group(List *tlist,
		   bool tuplePerGroup,
		   int ngrp,
		   AttrNumber *grpColIdx,
		   Sort *lefttree)
{
	Group	   *node = makeNode(Group);

    node->plan.cost = (lefttree ? lefttree->plan.cost : 0);
	node->plan.state = (EState *) NULL;
	node->plan.qual = NULL;
	node->plan.targetlist = tlist;
	node->plan.lefttree = (Plan *) lefttree;
	node->plan.righttree = (Plan *) NULL;
	node->tuplePerGroup = tuplePerGroup;
	node->numCols = ngrp;
	node->grpColIdx = grpColIdx;

	return (node);
}

/*
 *	A unique node always has a SORT node in the lefttree.
 *
 *	the uniqueAttr argument must be a null-terminated string,
 * either the name of the attribute to select unique on
 * or "*"
 */

Unique	   *
make_unique(List *tlist, Plan *lefttree, char *uniqueAttr)
{
	Unique	   *node = makeNode(Unique);
	Plan	   *plan = &node->plan;

    plan->cost = (lefttree ? lefttree->cost : 0);
	plan->state = (EState *) NULL;
	plan->targetlist = tlist;
	plan->qual = NIL;
	plan->lefttree = lefttree;
	plan->righttree = NULL;
	node->tempid = _TEMP_RELATION_ID_;
	node->keycount = 0;
	if (strcmp(uniqueAttr, "*") == 0)
		node->uniqueAttr = NULL;
	else
	{
		node->uniqueAttr = pstrdup(uniqueAttr);
	}
	return (node);
}

#ifdef NOT_USED
List	   *
generate_fjoin(List *tlist)
{
	List		tlistP;
	List		newTlist = NIL;
	List		fjoinList = NIL;
	int			nIters = 0;

	/*
	 * Break the target list into elements with Iter nodes, and those
	 * without them.
	 */
	foreach(tlistP, tlist)
	{
		List		tlistElem;

		tlistElem = lfirst(tlistP);
		if (IsA(lsecond(tlistElem), Iter))
		{
			nIters++;
			fjoinList = lappend(fjoinList, tlistElem);
		}
		else
		{
			newTlist = lappend(newTlist, tlistElem);
		}
	}

	/*
	 * if we have an Iter node then we need to flatten.
	 */
	if (nIters > 0)
	{
		List	   *inner;
		List	   *tempList;
		Fjoin	   *fjoinNode;
		DatumPtr	results = (DatumPtr) palloc(nIters * sizeof(Datum));
		BoolPtr		alwaysDone = (BoolPtr) palloc(nIters * sizeof(bool));

		inner = lfirst(fjoinList);
		fjoinList = lnext(fjoinList);
		fjoinNode = (Fjoin) MakeFjoin(false,
									  nIters,
									  inner,
									  results,
									  alwaysDone);
		tempList = lcons(fjoinNode, NIL);
		tempList = nconc(tempList, fjoinList);
		newTlist = lappend(newTlist, tempList);
	}
	return newTlist;
	return tlist;				/* do nothing for now - ay 10/94 */
}
#endif