text: /*-------------------------------------------------------------------------
   *
   * createplan.c
   *	  Routines to create the desired plan for processing a query.
   *	  Planning is complete, we just need to convert the selected
   *	  Path into a Plan.
   *
   * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/optimizer/plan/createplan.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include <limits.h>
  #include <math.h>
  
  #include "access/sysattr.h"
  #include "catalog/pg_class.h"
  #include "foreign/fdwapi.h"
  #include "miscadmin.h"
  #include "nodes/extensible.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/clauses.h"
  #include "optimizer/cost.h"
  #include "optimizer/optimizer.h"
  #include "optimizer/paramassign.h"
  #include "optimizer/paths.h"
  #include "optimizer/placeholder.h"
  #include "optimizer/plancat.h"
  #include "optimizer/planmain.h"
  #include "optimizer/restrictinfo.h"
  #include "optimizer/subselect.h"
  #include "optimizer/tlist.h"
  #include "parser/parse_clause.h"
  #include "parser/parsetree.h"
  #include "partitioning/partprune.h"
  #include "utils/lsyscache.h"
  
  
  /*
   * Flag bits that can appear in the flags argument of create_plan_recurse().
   * These can be OR-ed together.
   *
   * CP_EXACT_TLIST specifies that the generated plan node must return exactly
   * the tlist specified by the path's pathtarget (this overrides both
   * CP_SMALL_TLIST and CP_LABEL_TLIST, if those are set).  Otherwise, the
   * plan node is allowed to return just the Vars and PlaceHolderVars needed
   * to evaluate the pathtarget.
   *
   * CP_SMALL_TLIST specifies that a narrower tlist is preferred.  This is
   * passed down by parent nodes such as Sort and Hash, which will have to
   * store the returned tuples.
   *
   * CP_LABEL_TLIST specifies that the plan node must return columns matching
   * any sortgrouprefs specified in its pathtarget, with appropriate
   * ressortgroupref labels.  This is passed down by parent nodes such as Sort
   * and Group, which need these values to be available in their inputs.
   *
   * CP_IGNORE_TLIST specifies that the caller plans to replace the targetlist,
   * and therefore it doesn't matter a bit what target list gets generated.
   */
  #define CP_EXACT_TLIST		0x0001	/* Plan must return specified tlist */
  #define CP_SMALL_TLIST		0x0002	/* Prefer narrower tlists */
  #define CP_LABEL_TLIST		0x0004	/* tlist must contain sortgrouprefs */
  #define CP_IGNORE_TLIST		0x0008	/* caller will replace tlist */
  
  
  static Plan *create_plan_recurse(PlannerInfo *root, Path *best_path,
  								 int flags);
  static Plan *create_scan_plan(PlannerInfo *root, Path *best_path,
  							  int flags);
  static List *build_path_tlist(PlannerInfo *root, Path *path);
  static bool use_physical_tlist(PlannerInfo *root, Path *path, int flags);
  static List *get_gating_quals(PlannerInfo *root, List *quals);
  static Plan *create_gating_plan(PlannerInfo *root, Path *path, Plan *plan,
  								List *gating_quals);
  static Plan *create_join_plan(PlannerInfo *root, JoinPath *best_path);
  static Plan *create_append_plan(PlannerInfo *root, AppendPath *best_path,
  								int flags);
  static Plan *create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
  									  int flags);
  static Result *create_group_result_plan(PlannerInfo *root,
  										GroupResultPath *best_path);
  static ProjectSet *create_project_set_plan(PlannerInfo *root, ProjectSetPath *best_path);
  static Material *create_material_plan(PlannerInfo *root, MaterialPath *best_path,
  									  int flags);
  static Plan *create_unique_plan(PlannerInfo *root, UniquePath *best_path,
  								int flags);
  static Gather *create_gather_plan(PlannerInfo *root, GatherPath *best_path);
  static Plan *create_projection_plan(PlannerInfo *root,
  									ProjectionPath *best_path,
  									int flags);
  static Plan *inject_projection_plan(Plan *subplan, List *tlist, bool parallel_safe);
  static Sort *create_sort_plan(PlannerInfo *root, SortPath *best_path, int flags);
  static Group *create_group_plan(PlannerInfo *root, GroupPath *best_path);
  static Unique *create_upper_unique_plan(PlannerInfo *root, UpperUniquePath *best_path,
  										int flags);
  static Agg *create_agg_plan(PlannerInfo *root, AggPath *best_path);
  static Plan *create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path);
  static Result *create_minmaxagg_plan(PlannerInfo *root, MinMaxAggPath *best_path);
  static WindowAgg *create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path);
  static SetOp *create_setop_plan(PlannerInfo *root, SetOpPath *best_path,
  								int flags);
  static RecursiveUnion *create_recursiveunion_plan(PlannerInfo *root, RecursiveUnionPath *best_path);
  static LockRows *create_lockrows_plan(PlannerInfo *root, LockRowsPath *best_path,
  									  int flags);
  static ModifyTable *create_modifytable_plan(PlannerInfo *root, ModifyTablePath *best_path);
  static Limit *create_limit_plan(PlannerInfo *root, LimitPath *best_path,
  								int flags);
  static SeqScan *create_seqscan_plan(PlannerInfo *root, Path *best_path,
  									List *tlist, List *scan_clauses);
  static SampleScan *create_samplescan_plan(PlannerInfo *root, Path *best_path,
  										  List *tlist, List *scan_clauses);
  static Scan *create_indexscan_plan(PlannerInfo *root, IndexPath *best_path,
  								   List *tlist, List *scan_clauses, bool indexonly);
  static BitmapHeapScan *create_bitmap_scan_plan(PlannerInfo *root,
  											   BitmapHeapPath *best_path,
  											   List *tlist, List *scan_clauses);
  static Plan *create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
  								   List **qual, List **indexqual, List **indexECs);
  static void bitmap_subplan_mark_shared(Plan *plan);
  static TidScan *create_tidscan_plan(PlannerInfo *root, TidPath *best_path,
  									List *tlist, List *scan_clauses);
  static SubqueryScan *create_subqueryscan_plan(PlannerInfo *root,
  											  SubqueryScanPath *best_path,
  											  List *tlist, List *scan_clauses);
  static FunctionScan *create_functionscan_plan(PlannerInfo *root, Path *best_path,
  											  List *tlist, List *scan_clauses);
  static ValuesScan *create_valuesscan_plan(PlannerInfo *root, Path *best_path,
  										  List *tlist, List *scan_clauses);
  static TableFuncScan *create_tablefuncscan_plan(PlannerInfo *root, Path *best_path,
  												List *tlist, List *scan_clauses);
  static CteScan *create_ctescan_plan(PlannerInfo *root, Path *best_path,
  									List *tlist, List *scan_clauses);
  static NamedTuplestoreScan *create_namedtuplestorescan_plan(PlannerInfo *root,
  															Path *best_path, List *tlist, List *scan_clauses);
  static Result *create_resultscan_plan(PlannerInfo *root, Path *best_path,
  									  List *tlist, List *scan_clauses);
  static WorkTableScan *create_worktablescan_plan(PlannerInfo *root, Path *best_path,
  												List *tlist, List *scan_clauses);
  static ForeignScan *create_foreignscan_plan(PlannerInfo *root, ForeignPath *best_path,
  											List *tlist, List *scan_clauses);
  static CustomScan *create_customscan_plan(PlannerInfo *root,
  										  CustomPath *best_path,
  										  List *tlist, List *scan_clauses);
  static NestLoop *create_nestloop_plan(PlannerInfo *root, NestPath *best_path);
  static MergeJoin *create_mergejoin_plan(PlannerInfo *root, MergePath *best_path);
  static HashJoin *create_hashjoin_plan(PlannerInfo *root, HashPath *best_path);
  static Node *replace_nestloop_params(PlannerInfo *root, Node *expr);
  static Node *replace_nestloop_params_mutator(Node *node, PlannerInfo *root);
  static void fix_indexqual_references(PlannerInfo *root, IndexPath *index_path,
  									 List **stripped_indexquals_p,
  									 List **fixed_indexquals_p);
  static List *fix_indexorderby_references(PlannerInfo *root, IndexPath *index_path);
  static Node *fix_indexqual_clause(PlannerInfo *root,
  								  IndexOptInfo *index, int indexcol,
  								  Node *clause, List *indexcolnos);
  static Node *fix_indexqual_operand(Node *node, IndexOptInfo *index, int indexcol);
  static List *get_switched_clauses(List *clauses, Relids outerrelids);
  static List *order_qual_clauses(PlannerInfo *root, List *clauses);
  static void copy_generic_path_info(Plan *dest, Path *src);
  static void copy_plan_costsize(Plan *dest, Plan *src);
  static void label_sort_with_costsize(PlannerInfo *root, Sort *plan,
  									 double limit_tuples);
  static SeqScan *make_seqscan(List *qptlist, List *qpqual, Index scanrelid);
  static SampleScan *make_samplescan(List *qptlist, List *qpqual, Index scanrelid,
  								   TableSampleClause *tsc);
  static IndexScan *make_indexscan(List *qptlist, List *qpqual, Index scanrelid,
  								 Oid indexid, List *indexqual, List *indexqualorig,
  								 List *indexorderby, List *indexorderbyorig,
  								 List *indexorderbyops,
  								 ScanDirection indexscandir);
  static IndexOnlyScan *make_indexonlyscan(List *qptlist, List *qpqual,
  										 Index scanrelid, Oid indexid,
  										 List *indexqual, List *indexorderby,
  										 List *indextlist,
  										 ScanDirection indexscandir);
  static BitmapIndexScan *make_bitmap_indexscan(Index scanrelid, Oid indexid,
  											  List *indexqual,
  											  List *indexqualorig);
  static BitmapHeapScan *make_bitmap_heapscan(List *qptlist,
  											List *qpqual,
  											Plan *lefttree,
  											List *bitmapqualorig,
  											Index scanrelid);
  static TidScan *make_tidscan(List *qptlist, List *qpqual, Index scanrelid,
  							 List *tidquals);
  static SubqueryScan *make_subqueryscan(List *qptlist,
  									   List *qpqual,
  									   Index scanrelid,
  									   Plan *subplan);
  static FunctionScan *make_functionscan(List *qptlist, List *qpqual,
  									   Index scanrelid, List *functions, bool funcordinality);
  static ValuesScan *make_valuesscan(List *qptlist, List *qpqual,
  								   Index scanrelid, List *values_lists);
  static TableFuncScan *make_tablefuncscan(List *qptlist, List *qpqual,
  										 Index scanrelid, TableFunc *tablefunc);
  static CteScan *make_ctescan(List *qptlist, List *qpqual,
  							 Index scanrelid, int ctePlanId, int cteParam);
  static NamedTuplestoreScan *make_namedtuplestorescan(List *qptlist, List *qpqual,
  													 Index scanrelid, char *enrname);
  static WorkTableScan *make_worktablescan(List *qptlist, List *qpqual,
  										 Index scanrelid, int wtParam);
  static RecursiveUnion *make_recursive_union(List *tlist,
  											Plan *lefttree,
  											Plan *righttree,
  											int wtParam,
  											List *distinctList,
  											long numGroups);
  static BitmapAnd *make_bitmap_and(List *bitmapplans);
  static BitmapOr *make_bitmap_or(List *bitmapplans);
  static NestLoop *make_nestloop(List *tlist,
  							   List *joinclauses, List *otherclauses, List *nestParams,
  							   Plan *lefttree, Plan *righttree,
  							   JoinType jointype, bool inner_unique);
  static HashJoin *make_hashjoin(List *tlist,
  							   List *joinclauses, List *otherclauses,
  							   List *hashclauses,
  							   List *hashoperators, List *hashcollations,
  							   List *hashkeys,
  							   Plan *lefttree, Plan *righttree,
  							   JoinType jointype, bool inner_unique);
  static Hash *make_hash(Plan *lefttree,
  					   List *hashkeys,
  					   Oid skewTable,
  					   AttrNumber skewColumn,
  					   bool skewInherit);
  static MergeJoin *make_mergejoin(List *tlist,
  								 List *joinclauses, List *otherclauses,
  								 List *mergeclauses,
  								 Oid *mergefamilies,
  								 Oid *mergecollations,
  								 int *mergestrategies,
  								 bool *mergenullsfirst,
  								 Plan *lefttree, Plan *righttree,
  								 JoinType jointype, bool inner_unique,
  								 bool skip_mark_restore);
  static Sort *make_sort(Plan *lefttree, int numCols,
  					   AttrNumber *sortColIdx, Oid *sortOperators,
  					   Oid *collations, bool *nullsFirst);
  static Plan *prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
  										Relids relids,
  										const AttrNumber *reqColIdx,
  										bool adjust_tlist_in_place,
  										int *p_numsortkeys,
  										AttrNumber **p_sortColIdx,
  										Oid **p_sortOperators,
  										Oid **p_collations,
  										bool **p_nullsFirst);
  static EquivalenceMember *find_ec_member_for_tle(EquivalenceClass *ec,
  												 TargetEntry *tle,
  												 Relids relids);
  static Sort *make_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
  									 Relids relids);
  static Sort *make_sort_from_groupcols(List *groupcls,
  									  AttrNumber *grpColIdx,
  									  Plan *lefttree);
  static Material *make_material(Plan *lefttree);
  static WindowAgg *make_windowagg(List *tlist, Index winref,
  								 int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
  								 int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
  								 int frameOptions, Node *startOffset, Node *endOffset,
  								 Oid startInRangeFunc, Oid endInRangeFunc,
  								 Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
  								 Plan *lefttree);
  static Group *make_group(List *tlist, List *qual, int numGroupCols,
  						 AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
  						 Plan *lefttree);
  static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
  static Unique *make_unique_from_pathkeys(Plan *lefttree,
  										 List *pathkeys, int numCols);
  static Gather *make_gather(List *qptlist, List *qpqual,
  						   int nworkers, int rescan_param, bool single_copy, Plan *subplan);
  static SetOp *make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
  						 List *distinctList, AttrNumber flagColIdx, int firstFlag,
  						 long numGroups);
  static LockRows *make_lockrows(Plan *lefttree, List *rowMarks, int epqParam);
  static Result *make_result(List *tlist, Node *resconstantqual, Plan *subplan);
  static ProjectSet *make_project_set(List *tlist, Plan *subplan);
  static ModifyTable *make_modifytable(PlannerInfo *root,
  									 CmdType operation, bool canSetTag,
  									 Index nominalRelation, Index rootRelation,
  									 bool partColsUpdated,
  									 List *resultRelations, List *subplans, List *subroots,
  									 List *withCheckOptionLists, List *returningLists,
  									 List *rowMarks, OnConflictExpr *onconflict, int epqParam);
  static GatherMerge *create_gather_merge_plan(PlannerInfo *root,
  											 GatherMergePath *best_path);
  
  
  /*
   * create_plan
   *	  Creates the access plan for a query by recursively processing the
   *	  desired tree of pathnodes, starting at the node 'best_path'.  For
   *	  every pathnode found, we create a corresponding plan node containing
   *	  appropriate id, target list, and qualification information.
   *
   *	  The tlists and quals in the plan tree are still in planner format,
   *	  ie, Vars still correspond to the parser's numbering.  This will be
   *	  fixed later by setrefs.c.
   *
   *	  best_path is the best access path
   *
   *	  Returns a Plan tree.
   */
  Plan *
  create_plan(PlannerInfo *root, Path *best_path)
  {
  	Plan	   *plan;
  
  	/* plan_params should not be in use in current query level */
  	Assert(root->plan_params == NIL);
  
  	/* Initialize this module's workspace in PlannerInfo */
  	root->curOuterRels = NULL;
  	root->curOuterParams = NIL;
  
  	/* Recursively process the path tree, demanding the correct tlist result */
  	plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
  
  	/*
  	 * Make sure the topmost plan node's targetlist exposes the original
  	 * column names and other decorative info.  Targetlists generated within
  	 * the planner don't bother with that stuff, but we must have it on the
  	 * top-level tlist seen at execution time.  However, ModifyTable plan
  	 * nodes don't have a tlist matching the querytree targetlist.
  	 */
  	if (!IsA(plan, ModifyTable))
  		apply_tlist_labeling(plan->targetlist, root->processed_tlist);
  
  	/*
  	 * Attach any initPlans created in this query level to the topmost plan
  	 * node.  (In principle the initplans could go in any plan node at or
  	 * above where they're referenced, but there seems no reason to put them
  	 * any lower than the topmost node for the query level.  Also, see
  	 * comments for SS_finalize_plan before you try to change this.)
  	 */
  	SS_attach_initplans(root, plan);
  
  	/* Check we successfully assigned all NestLoopParams to plan nodes */
  	if (root->curOuterParams != NIL)
  		elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
  
  	/*
  	 * Reset plan_params to ensure param IDs used for nestloop params are not
  	 * re-used later
  	 */
  	root->plan_params = NIL;
  
  	return plan;
  }
  
  /*
   * create_plan_recurse
   *	  Recursive guts of create_plan().
   */
  static Plan *
  create_plan_recurse(PlannerInfo *root, Path *best_path, int flags)
  {
  	Plan	   *plan;
  
  	/* Guard against stack overflow due to overly complex plans */
  	check_stack_depth();
  
  	switch (best_path->pathtype)
  	{
  		case T_SeqScan:
  		case T_SampleScan:
  		case T_IndexScan:
  		case T_IndexOnlyScan:
  		case T_BitmapHeapScan:
  		case T_TidScan:
  		case T_SubqueryScan:
  		case T_FunctionScan:
  		case T_TableFuncScan:
  		case T_ValuesScan:
  		case T_CteScan:
  		case T_WorkTableScan:
  		case T_NamedTuplestoreScan:
  		case T_ForeignScan:
  		case T_CustomScan:
  			plan = create_scan_plan(root, best_path, flags);
  			break;
  		case T_HashJoin:
  		case T_MergeJoin:
  		case T_NestLoop:
  			plan = create_join_plan(root,
  									(JoinPath *) best_path);
  			break;
  		case T_Append:
  			plan = create_append_plan(root,
  									  (AppendPath *) best_path,
  									  flags);
  			break;
  		case T_MergeAppend:
  			plan = create_merge_append_plan(root,
  											(MergeAppendPath *) best_path,
  											flags);
  			break;
  		case T_Result:
  			if (IsA(best_path, ProjectionPath))
  			{
  				plan = create_projection_plan(root,
  											  (ProjectionPath *) best_path,
  											  flags);
  			}
  			else if (IsA(best_path, MinMaxAggPath))
  			{
  				plan = (Plan *) create_minmaxagg_plan(root,
  													  (MinMaxAggPath *) best_path);
  			}
  			else if (IsA(best_path, GroupResultPath))
  			{
  				plan = (Plan *) create_group_result_plan(root,
  														 (GroupResultPath *) best_path);
  			}
  			else
  			{
  				/* Simple RTE_RESULT base relation */
  				Assert(IsA(best_path, Path));
  				plan = create_scan_plan(root, best_path, flags);
  			}
  			break;
  		case T_ProjectSet:
  			plan = (Plan *) create_project_set_plan(root,
  													(ProjectSetPath *) best_path);
  			break;
  		case T_Material:
  			plan = (Plan *) create_material_plan(root,
  												 (MaterialPath *) best_path,
  												 flags);
  			break;
  		case T_Unique:
  			if (IsA(best_path, UpperUniquePath))
  			{
  				plan = (Plan *) create_upper_unique_plan(root,
  														 (UpperUniquePath *) best_path,
  														 flags);
  			}
  			else
  			{
  				Assert(IsA(best_path, UniquePath));
  				plan = create_unique_plan(root,
  										  (UniquePath *) best_path,
  										  flags);
  			}
  			break;
  		case T_Gather:
  			plan = (Plan *) create_gather_plan(root,
  											   (GatherPath *) best_path);
  			break;
  		case T_Sort:
  			plan = (Plan *) create_sort_plan(root,
  											 (SortPath *) best_path,
  											 flags);
  			break;
  		case T_Group:
  			plan = (Plan *) create_group_plan(root,
  											  (GroupPath *) best_path);
  			break;
  		case T_Agg:
  			if (IsA(best_path, GroupingSetsPath))
  				plan = create_groupingsets_plan(root,
  												(GroupingSetsPath *) best_path);
  			else
  			{
  				Assert(IsA(best_path, AggPath));
  				plan = (Plan *) create_agg_plan(root,
  												(AggPath *) best_path);
  			}
  			break;
  		case T_WindowAgg:
  			plan = (Plan *) create_windowagg_plan(root,
  												  (WindowAggPath *) best_path);
  			break;
  		case T_SetOp:
  			plan = (Plan *) create_setop_plan(root,
  											  (SetOpPath *) best_path,
  											  flags);
  			break;
  		case T_RecursiveUnion:
  			plan = (Plan *) create_recursiveunion_plan(root,
  													   (RecursiveUnionPath *) best_path);
  			break;
  		case T_LockRows:
  			plan = (Plan *) create_lockrows_plan(root,
  												 (LockRowsPath *) best_path,
  												 flags);
  			break;
  		case T_ModifyTable:
  			plan = (Plan *) create_modifytable_plan(root,
  													(ModifyTablePath *) best_path);
  			break;
  		case T_Limit:
  			plan = (Plan *) create_limit_plan(root,
  											  (LimitPath *) best_path,
  											  flags);
  			break;
  		case T_GatherMerge:
  			plan = (Plan *) create_gather_merge_plan(root,
  													 (GatherMergePath *) best_path);
  			break;
  		default:
  			elog(ERROR, "unrecognized node type: %d",
  				 (int) best_path->pathtype);
  			plan = NULL;		/* keep compiler quiet */
  			break;
  	}
  
  	return plan;
  }
  
  /*
   * create_scan_plan
   *	 Create a scan plan for the parent relation of 'best_path'.
   */
  static Plan *
  create_scan_plan(PlannerInfo *root, Path *best_path, int flags)
  {
  	RelOptInfo *rel = best_path->parent;
  	List	   *scan_clauses;
  	List	   *gating_clauses;
  	List	   *tlist;
  	Plan	   *plan;
  
  	/*
  	 * Extract the relevant restriction clauses from the parent relation. The
  	 * executor must apply all these restrictions during the scan, except for
  	 * pseudoconstants which we'll take care of below.
  	 *
  	 * If this is a plain indexscan or index-only scan, we need not consider
  	 * restriction clauses that are implied by the index's predicate, so use
  	 * indrestrictinfo not baserestrictinfo.  Note that we can't do that for
  	 * bitmap indexscans, since there's not necessarily a single index
  	 * involved; but it doesn't matter since create_bitmap_scan_plan() will be
  	 * able to get rid of such clauses anyway via predicate proof.
  	 */
  	switch (best_path->pathtype)
  	{
  		case T_IndexScan:
  		case T_IndexOnlyScan:
  			scan_clauses = castNode(IndexPath, best_path)->indexinfo->indrestrictinfo;
  			break;
  		default:
  			scan_clauses = rel->baserestrictinfo;
  			break;
  	}
  
  	/*
  	 * If this is a parameterized scan, we also need to enforce all the join
  	 * clauses available from the outer relation(s).
  	 *
  	 * For paranoia's sake, don't modify the stored baserestrictinfo list.
  	 */
  	if (best_path->param_info)
  		scan_clauses = list_concat(list_copy(scan_clauses),
  								   best_path->param_info->ppi_clauses);
  
  	/*
  	 * Detect whether we have any pseudoconstant quals to deal with.  Then, if
  	 * we'll need a gating Result node, it will be able to project, so there
  	 * are no requirements on the child's tlist.
  	 */
  	gating_clauses = get_gating_quals(root, scan_clauses);
  	if (gating_clauses)
  		flags = 0;
  
  	/*
  	 * For table scans, rather than using the relation targetlist (which is
  	 * only those Vars actually needed by the query), we prefer to generate a
  	 * tlist containing all Vars in order.  This will allow the executor to
  	 * optimize away projection of the table tuples, if possible.
  	 *
  	 * But if the caller is going to ignore our tlist anyway, then don't
  	 * bother generating one at all.  We use an exact equality test here, so
  	 * that this only applies when CP_IGNORE_TLIST is the only flag set.
  	 */
  	if (flags == CP_IGNORE_TLIST)
  	{
  		tlist = NULL;
  	}
  	else if (use_physical_tlist(root, best_path, flags))
  	{
  		if (best_path->pathtype == T_IndexOnlyScan)
  		{
  			/* For index-only scan, the preferred tlist is the index's */
  			tlist = copyObject(((IndexPath *) best_path)->indexinfo->indextlist);
  
  			/*
  			 * Transfer sortgroupref data to the replacement tlist, if
  			 * requested (use_physical_tlist checked that this will work).
  			 */
  			if (flags & CP_LABEL_TLIST)
  				apply_pathtarget_labeling_to_tlist(tlist, best_path->pathtarget);
  		}
  		else
  		{
  			tlist = build_physical_tlist(root, rel);
  			if (tlist == NIL)
  			{
  				/* Failed because of dropped cols, so use regular method */
  				tlist = build_path_tlist(root, best_path);
  			}
  			else
  			{
  				/* As above, transfer sortgroupref data to replacement tlist */
  				if (flags & CP_LABEL_TLIST)
  					apply_pathtarget_labeling_to_tlist(tlist, best_path->pathtarget);
  			}
  		}
  	}
  	else
  	{
  		tlist = build_path_tlist(root, best_path);
  	}
  
  	switch (best_path->pathtype)
  	{
  		case T_SeqScan:
  			plan = (Plan *) create_seqscan_plan(root,
  												best_path,
  												tlist,
  												scan_clauses);
  			break;
  
  		case T_SampleScan:
  			plan = (Plan *) create_samplescan_plan(root,
  												   best_path,
  												   tlist,
  												   scan_clauses);
  			break;
  
  		case T_IndexScan:
  			plan = (Plan *) create_indexscan_plan(root,
  												  (IndexPath *) best_path,
  												  tlist,
  												  scan_clauses,
  												  false);
  			break;
  
  		case T_IndexOnlyScan:
  			plan = (Plan *) create_indexscan_plan(root,
  												  (IndexPath *) best_path,
  												  tlist,
  												  scan_clauses,
  												  true);
  			break;
  
  		case T_BitmapHeapScan:
  			plan = (Plan *) create_bitmap_scan_plan(root,
  													(BitmapHeapPath *) best_path,
  													tlist,
  													scan_clauses);
  			break;
  
  		case T_TidScan:
  			plan = (Plan *) create_tidscan_plan(root,
  												(TidPath *) best_path,
  												tlist,
  												scan_clauses);
  			break;
  
  		case T_SubqueryScan:
  			plan = (Plan *) create_subqueryscan_plan(root,
  													 (SubqueryScanPath *) best_path,
  													 tlist,
  													 scan_clauses);
  			break;
  
  		case T_FunctionScan:
  			plan = (Plan *) create_functionscan_plan(root,
  													 best_path,
  													 tlist,
  													 scan_clauses);
  			break;
  
  		case T_TableFuncScan:
  			plan = (Plan *) create_tablefuncscan_plan(root,
  													  best_path,
  													  tlist,
  													  scan_clauses);
  			break;
  
  		case T_ValuesScan:
  			plan = (Plan *) create_valuesscan_plan(root,
  												   best_path,
  												   tlist,
  												   scan_clauses);
  			break;
  
  		case T_CteScan:
  			plan = (Plan *) create_ctescan_plan(root,
  												best_path,
  												tlist,
  												scan_clauses);
  			break;
  
  		case T_NamedTuplestoreScan:
  			plan = (Plan *) create_namedtuplestorescan_plan(root,
  															best_path,
  															tlist,
  															scan_clauses);
  			break;
  
  		case T_Result:
  			plan = (Plan *) create_resultscan_plan(root,
  												   best_path,
  												   tlist,
  												   scan_clauses);
  			break;
  
  		case T_WorkTableScan:
  			plan = (Plan *) create_worktablescan_plan(root,
  													  best_path,
  													  tlist,
  													  scan_clauses);
  			break;
  
  		case T_ForeignScan:
  			plan = (Plan *) create_foreignscan_plan(root,
  													(ForeignPath *) best_path,
  													tlist,
  													scan_clauses);
  			break;
  
  		case T_CustomScan:
  			plan = (Plan *) create_customscan_plan(root,
  												   (CustomPath *) best_path,
  												   tlist,
  												   scan_clauses);
  			break;
  
  		default:
  			elog(ERROR, "unrecognized node type: %d",
  				 (int) best_path->pathtype);
  			plan = NULL;		/* keep compiler quiet */
  			break;
  	}
  
  	/*
  	 * If there are any pseudoconstant clauses attached to this node, insert a
  	 * gating Result node that evaluates the pseudoconstants as one-time
  	 * quals.
  	 */
  	if (gating_clauses)
  		plan = create_gating_plan(root, best_path, plan, gating_clauses);
  
  	return plan;
  }
  
  /*
   * Build a target list (ie, a list of TargetEntry) for the Path's output.
   *
   * This is almost just make_tlist_from_pathtarget(), but we also have to
   * deal with replacing nestloop params.
   */
  static List *
  build_path_tlist(PlannerInfo *root, Path *path)
  {
  	List	   *tlist = NIL;
  	Index	   *sortgrouprefs = path->pathtarget->sortgrouprefs;
  	int			resno = 1;
  	ListCell   *v;
  
  	foreach(v, path->pathtarget->exprs)
  	{
  		Node	   *node = (Node *) lfirst(v);
  		TargetEntry *tle;
  
  		/*
  		 * If it's a parameterized path, there might be lateral references in
  		 * the tlist, which need to be replaced with Params.  There's no need
  		 * to remake the TargetEntry nodes, so apply this to each list item
  		 * separately.
  		 */
  		if (path->param_info)
  			node = replace_nestloop_params(root, node);
  
  		tle = makeTargetEntry((Expr *) node,
  							  resno,
  							  NULL,
  							  false);
  		if (sortgrouprefs)
  			tle->ressortgroupref = sortgrouprefs[resno - 1];
  
  		tlist = lappend(tlist, tle);
  		resno++;
  	}
  	return tlist;
  }
  
  /*
   * use_physical_tlist
   *		Decide whether to use a tlist matching relation structure,
   *		rather than only those Vars actually referenced.
   */
  static bool
  use_physical_tlist(PlannerInfo *root, Path *path, int flags)
  {
  	RelOptInfo *rel = path->parent;
  	int			i;
  	ListCell   *lc;
  
  	/*
  	 * Forget it if either exact tlist or small tlist is demanded.
  	 */
  	if (flags & (CP_EXACT_TLIST | CP_SMALL_TLIST))
  		return false;
  
  	/*
  	 * We can do this for real relation scans, subquery scans, function scans,
  	 * tablefunc scans, values scans, and CTE scans (but not for, eg, joins).
  	 */
  	if (rel->rtekind != RTE_RELATION &&
  		rel->rtekind != RTE_SUBQUERY &&
  		rel->rtekind != RTE_FUNCTION &&
  		rel->rtekind != RTE_TABLEFUNC &&
  		rel->rtekind != RTE_VALUES &&
  		rel->rtekind != RTE_CTE)
  		return false;
  
  	/*
  	 * Can't do it with inheritance cases either (mainly because Append
  	 * doesn't project; this test may be unnecessary now that
  	 * create_append_plan instructs its children to return an exact tlist).
  	 */
  	if (rel->reloptkind != RELOPT_BASEREL)
  		return false;
  
  	/*
  	 * Also, don't do it to a CustomPath; the premise that we're extracting
  	 * columns from a simple physical tuple is unlikely to hold for those.
  	 * (When it does make sense, the custom path creator can set up the path's
  	 * pathtarget that way.)
  	 */
  	if (IsA(path, CustomPath))
  		return false;
  
  	/*
  	 * If a bitmap scan's tlist is empty, keep it as-is.  This may allow the
  	 * executor to skip heap page fetches, and in any case, the benefit of
  	 * using a physical tlist instead would be minimal.
  	 */
  	if (IsA(path, BitmapHeapPath) &&
  		path->pathtarget->exprs == NIL)
  		return false;
  
  	/*
  	 * Can't do it if any system columns or whole-row Vars are requested.
  	 * (This could possibly be fixed but would take some fragile assumptions
  	 * in setrefs.c, I think.)
  	 */
  	for (i = rel->min_attr; i <= 0; i++)
  	{
  		if (!bms_is_empty(rel->attr_needed[i - rel->min_attr]))
  			return false;
  	}
  
  	/*
  	 * Can't do it if the rel is required to emit any placeholder expressions,
  	 * either.
  	 */
  	foreach(lc, root->placeholder_list)
  	{
  		PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
  
  		if (bms_nonempty_difference(phinfo->ph_needed, rel->relids) &&
  			bms_is_subset(phinfo->ph_eval_at, rel->relids))
  			return false;
  	}
  
  	/*
  	 * Also, can't do it if CP_LABEL_TLIST is specified and path is requested
  	 * to emit any sort/group columns that are not simple Vars.  (If they are
  	 * simple Vars, they should appear in the physical tlist, and
  	 * apply_pathtarget_labeling_to_tlist will take care of getting them
  	 * labeled again.)	We also have to check that no two sort/group columns
  	 * are the same Var, else that element of the physical tlist would need
  	 * conflicting ressortgroupref labels.
  	 */
  	if ((flags & CP_LABEL_TLIST) && path->pathtarget->sortgrouprefs)
  	{
  		Bitmapset  *sortgroupatts = NULL;
  
  		i = 0;
  		foreach(lc, path->pathtarget->exprs)
  		{
  			Expr	   *expr = (Expr *) lfirst(lc);
  
  			if (path->pathtarget->sortgrouprefs[i])
  			{
  				if (expr && IsA(expr, Var))
  				{
  					int			attno = ((Var *) expr)->varattno;
  
  					attno -= FirstLowInvalidHeapAttributeNumber;
  					if (bms_is_member(attno, sortgroupatts))
  						return false;
  					sortgroupatts = bms_add_member(sortgroupatts, attno);
  				}
  				else
  					return false;
  			}
  			i++;
  		}
  	}
  
  	return true;
  }
  
  /*
   * get_gating_quals
   *	  See if there are pseudoconstant quals in a node's quals list
   *
   * If the node's quals list includes any pseudoconstant quals,
   * return just those quals.
   */
  static List *
  get_gating_quals(PlannerInfo *root, List *quals)
  {
  	/* No need to look if we know there are no pseudoconstants */
  	if (!root->hasPseudoConstantQuals)
  		return NIL;
  
  	/* Sort into desirable execution order while still in RestrictInfo form */
  	quals = order_qual_clauses(root, quals);
  
  	/* Pull out any pseudoconstant quals from the RestrictInfo list */
  	return extract_actual_clauses(quals, true);
  }
  
  /*
   * create_gating_plan
   *	  Deal with pseudoconstant qual clauses
   *
   * Add a gating Result node atop the already-built plan.
   */
  static Plan *
  create_gating_plan(PlannerInfo *root, Path *path, Plan *plan,
  				   List *gating_quals)
  {
  	Plan	   *gplan;
  	Plan	   *splan;
  
  	Assert(gating_quals);
  
  	/*
  	 * We might have a trivial Result plan already.  Stacking one Result atop
  	 * another is silly, so if that applies, just discard the input plan.
  	 * (We're assuming its targetlist is uninteresting; it should be either
  	 * the same as the result of build_path_tlist, or a simplified version.)
  	 */
  	splan = plan;
  	if (IsA(plan, Result))
  	{
  		Result	   *rplan = (Result *) plan;
  
  		if (rplan->plan.lefttree == NULL &&
  			rplan->resconstantqual == NULL)
  			splan = NULL;
  	}
  
  	/*
  	 * Since we need a Result node anyway, always return the path's requested
  	 * tlist; that's never a wrong choice, even if the parent node didn't ask
  	 * for CP_EXACT_TLIST.
  	 */
  	gplan = (Plan *) make_result(build_path_tlist(root, path),
  								 (Node *) gating_quals,
  								 splan);
  
  	/*
  	 * Notice that we don't change cost or size estimates when doing gating.
  	 * The costs of qual eval were already included in the subplan's cost.
  	 * Leaving the size alone amounts to assuming that the gating qual will
  	 * succeed, which is the conservative estimate for planning upper queries.
  	 * We certainly don't want to assume the output size is zero (unless the
  	 * gating qual is actually constant FALSE, and that case is dealt with in
  	 * clausesel.c).  Interpolating between the two cases is silly, because it
  	 * doesn't reflect what will really happen at runtime, and besides which
  	 * in most cases we have only a very bad idea of the probability of the
  	 * gating qual being true.
  	 */
  	copy_plan_costsize(gplan, plan);
  
  	/* Gating quals could be unsafe, so better use the Path's safety flag */
  	gplan->parallel_safe = path->parallel_safe;
  
  	return gplan;
  }
  
  /*
   * create_join_plan
   *	  Create a join plan for 'best_path' and (recursively) plans for its
   *	  inner and outer paths.
   */
  static Plan *
  create_join_plan(PlannerInfo *root, JoinPath *best_path)
  {
  	Plan	   *plan;
  	List	   *gating_clauses;
  
  	switch (best_path->path.pathtype)
  	{
  		case T_MergeJoin:
  			plan = (Plan *) create_mergejoin_plan(root,
  												  (MergePath *) best_path);
  			break;
  		case T_HashJoin:
  			plan = (Plan *) create_hashjoin_plan(root,
  												 (HashPath *) best_path);
  			break;
  		case T_NestLoop:
  			plan = (Plan *) create_nestloop_plan(root,
  												 (NestPath *) best_path);
  			break;
  		default:
  			elog(ERROR, "unrecognized node type: %d",
  				 (int) best_path->path.pathtype);
  			plan = NULL;		/* keep compiler quiet */
  			break;
  	}
  
  	/*
  	 * If there are any pseudoconstant clauses attached to this node, insert a
  	 * gating Result node that evaluates the pseudoconstants as one-time
  	 * quals.
  	 */
  	gating_clauses = get_gating_quals(root, best_path->joinrestrictinfo);
  	if (gating_clauses)
  		plan = create_gating_plan(root, (Path *) best_path, plan,
  								  gating_clauses);
  
  #ifdef NOT_USED
  
  	/*
  	 * * 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_loc_restrictinfo(best_path) != NIL)
  		set_qpqual((Plan) plan,
  				   list_concat(get_qpqual((Plan) plan),
  							   get_actual_clauses(get_loc_restrictinfo(best_path))));
  #endif
  
  	return plan;
  }
  
  /*
   * create_append_plan
   *	  Create an Append plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   *
   *	  Returns a Plan node.
   */
  static Plan *
  create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
  {
  	Append	   *plan;
  	List	   *tlist = build_path_tlist(root, &best_path->path);
  	int			orig_tlist_length = list_length(tlist);
  	bool		tlist_was_changed = false;
  	List	   *pathkeys = best_path->path.pathkeys;
  	List	   *subplans = NIL;
  	ListCell   *subpaths;
  	RelOptInfo *rel = best_path->path.parent;
  	PartitionPruneInfo *partpruneinfo = NULL;
  	int			nodenumsortkeys = 0;
  	AttrNumber *nodeSortColIdx = NULL;
  	Oid		   *nodeSortOperators = NULL;
  	Oid		   *nodeCollations = NULL;
  	bool	   *nodeNullsFirst = NULL;
  
  	/*
  	 * The subpaths list could be empty, if every child was proven empty by
  	 * constraint exclusion.  In that case generate a dummy plan that returns
  	 * no rows.
  	 *
  	 * Note that an AppendPath with no members is also generated in certain
  	 * cases where there was no appending construct at all, but we know the
  	 * relation is empty (see set_dummy_rel_pathlist and mark_dummy_rel).
  	 */
  	if (best_path->subpaths == NIL)
  	{
  		/* Generate a Result plan with constant-FALSE gating qual */
  		Plan	   *plan;
  
  		plan = (Plan *) make_result(tlist,
  									(Node *) list_make1(makeBoolConst(false,
  																	  false)),
  									NULL);
  
  		copy_generic_path_info(plan, (Path *) best_path);
  
  		return plan;
  	}
  
  	/*
  	 * Otherwise build an Append plan.  Note that if there's just one child,
  	 * the Append is pretty useless; but we wait till setrefs.c to get rid of
  	 * it.  Doing so here doesn't work because the varno of the child scan
  	 * plan won't match the parent-rel Vars it'll be asked to emit.
  	 *
  	 * We don't have the actual creation of the Append node split out into a
  	 * separate make_xxx function.  This is because we want to run
  	 * prepare_sort_from_pathkeys on it before we do so on the individual
  	 * child plans, to make cross-checking the sort info easier.
  	 */
  	plan = makeNode(Append);
  	plan->plan.targetlist = tlist;
  	plan->plan.qual = NIL;
  	plan->plan.lefttree = NULL;
  	plan->plan.righttree = NULL;
  
  	if (pathkeys != NIL)
  	{
  		/*
  		 * Compute sort column info, and adjust the Append's tlist as needed.
  		 * Because we pass adjust_tlist_in_place = true, we may ignore the
  		 * function result; it must be the same plan node.  However, we then
  		 * need to detect whether any tlist entries were added.
  		 */
  		(void) prepare_sort_from_pathkeys((Plan *) plan, pathkeys,
  										  best_path->path.parent->relids,
  										  NULL,
  										  true,
  										  &nodenumsortkeys,
  										  &nodeSortColIdx,
  										  &nodeSortOperators,
  										  &nodeCollations,
  										  &nodeNullsFirst);
  		tlist_was_changed = (orig_tlist_length != list_length(plan->plan.targetlist));
  	}
  
  	/* Build the plan for each child */
  	foreach(subpaths, best_path->subpaths)
  	{
  		Path	   *subpath = (Path *) lfirst(subpaths);
  		Plan	   *subplan;
  
  		/* Must insist that all children return the same tlist */
  		subplan = create_plan_recurse(root, subpath, CP_EXACT_TLIST);
  
  		/*
  		 * For ordered Appends, we must insert a Sort node if subplan isn't
  		 * sufficiently ordered.
  		 */
  		if (pathkeys != NIL)
  		{
  			int			numsortkeys;
  			AttrNumber *sortColIdx;
  			Oid		   *sortOperators;
  			Oid		   *collations;
  			bool	   *nullsFirst;
  
  			/*
  			 * Compute sort column info, and adjust subplan's tlist as needed.
  			 * We must apply prepare_sort_from_pathkeys even to subplans that
  			 * don't need an explicit sort, to make sure they are returning
  			 * the same sort key columns the Append expects.
  			 */
  			subplan = prepare_sort_from_pathkeys(subplan, pathkeys,
  												 subpath->parent->relids,
  												 nodeSortColIdx,
  												 false,
  												 &numsortkeys,
  												 &sortColIdx,
  												 &sortOperators,
  												 &collations,
  												 &nullsFirst);
  
  			/*
  			 * Check that we got the same sort key information.  We just
  			 * Assert that the sortops match, since those depend only on the
  			 * pathkeys; but it seems like a good idea to check the sort
  			 * column numbers explicitly, to ensure the tlists match up.
  			 */
  			Assert(numsortkeys == nodenumsortkeys);
  			if (memcmp(sortColIdx, nodeSortColIdx,
  					   numsortkeys * sizeof(AttrNumber)) != 0)
  				elog(ERROR, "Append child's targetlist doesn't match Append");
  			Assert(memcmp(sortOperators, nodeSortOperators,
  						  numsortkeys * sizeof(Oid)) == 0);
  			Assert(memcmp(collations, nodeCollations,
  						  numsortkeys * sizeof(Oid)) == 0);
  			Assert(memcmp(nullsFirst, nodeNullsFirst,
  						  numsortkeys * sizeof(bool)) == 0);
  
  			/* Now, insert a Sort node if subplan isn't sufficiently ordered */
  			if (!pathkeys_contained_in(pathkeys, subpath->pathkeys))
  			{
  				Sort	   *sort = make_sort(subplan, numsortkeys,
  											 sortColIdx, sortOperators,
  											 collations, nullsFirst);
  
  				label_sort_with_costsize(root, sort, best_path->limit_tuples);
  				subplan = (Plan *) sort;
  			}
  		}
  
  		subplans = lappend(subplans, subplan);
  	}
  
  	/*
  	 * If any quals exist, they may be useful to perform further partition
  	 * pruning during execution.  Gather information needed by the executor to
  	 * do partition pruning.
  	 */
  	if (enable_partition_pruning &&
  		rel->reloptkind == RELOPT_BASEREL &&
  		best_path->partitioned_rels != NIL)
  	{
  		List	   *prunequal;
  
  		prunequal = extract_actual_clauses(rel->baserestrictinfo, false);
  
  		if (best_path->path.param_info)
  		{
  			List	   *prmquals = best_path->path.param_info->ppi_clauses;
  
  			prmquals = extract_actual_clauses(prmquals, false);
  			prmquals = (List *) replace_nestloop_params(root,
  														(Node *) prmquals);
  
  			prunequal = list_concat(prunequal, prmquals);
  		}
  
  		if (prunequal != NIL)
  			partpruneinfo =
  				make_partition_pruneinfo(root, rel,
  										 best_path->subpaths,
  										 best_path->partitioned_rels,
  										 prunequal);
  	}
  
  	plan->appendplans = subplans;
  	plan->first_partial_plan = best_path->first_partial_path;
  	plan->part_prune_info = partpruneinfo;
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	/*
  	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
  	 * produce either the exact tlist or a narrow tlist, we should get rid of
  	 * the sort columns again.  We must inject a projection node to do so.
  	 */
  	if (tlist_was_changed && (flags & (CP_EXACT_TLIST | CP_SMALL_TLIST)))
  	{
  		tlist = list_truncate(list_copy(plan->plan.targetlist),
  							  orig_tlist_length);
  		return inject_projection_plan((Plan *) plan, tlist,
  									  plan->plan.parallel_safe);
  	}
  	else
  		return (Plan *) plan;
  }
  
  /*
   * create_merge_append_plan
   *	  Create a MergeAppend plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   *
   *	  Returns a Plan node.
   */
  static Plan *
  create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
  						 int flags)
  {
  	MergeAppend *node = makeNode(MergeAppend);
  	Plan	   *plan = &node->plan;
  	List	   *tlist = build_path_tlist(root, &best_path->path);
  	int			orig_tlist_length = list_length(tlist);
  	bool		tlist_was_changed;
  	List	   *pathkeys = best_path->path.pathkeys;
  	List	   *subplans = NIL;
  	ListCell   *subpaths;
  	RelOptInfo *rel = best_path->path.parent;
  	PartitionPruneInfo *partpruneinfo = NULL;
  
  	/*
  	 * We don't have the actual creation of the MergeAppend node split out
  	 * into a separate make_xxx function.  This is because we want to run
  	 * prepare_sort_from_pathkeys on it before we do so on the individual
  	 * child plans, to make cross-checking the sort info easier.
  	 */
  	copy_generic_path_info(plan, (Path *) best_path);
  	plan->targetlist = tlist;
  	plan->qual = NIL;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  
  	/*
  	 * Compute sort column info, and adjust MergeAppend's tlist as needed.
  	 * Because we pass adjust_tlist_in_place = true, we may ignore the
  	 * function result; it must be the same plan node.  However, we then need
  	 * to detect whether any tlist entries were added.
  	 */
  	(void) prepare_sort_from_pathkeys(plan, pathkeys,
  									  best_path->path.parent->relids,
  									  NULL,
  									  true,
  									  &node->numCols,
  									  &node->sortColIdx,
  									  &node->sortOperators,
  									  &node->collations,
  									  &node->nullsFirst);
  	tlist_was_changed = (orig_tlist_length != list_length(plan->targetlist));
  
  	/*
  	 * Now prepare the child plans.  We must apply prepare_sort_from_pathkeys
  	 * even to subplans that don't need an explicit sort, to make sure they
  	 * are returning the same sort key columns the MergeAppend expects.
  	 */
  	foreach(subpaths, best_path->subpaths)
  	{
  		Path	   *subpath = (Path *) lfirst(subpaths);
  		Plan	   *subplan;
  		int			numsortkeys;
  		AttrNumber *sortColIdx;
  		Oid		   *sortOperators;
  		Oid		   *collations;
  		bool	   *nullsFirst;
  
  		/* Build the child plan */
  		/* Must insist that all children return the same tlist */
  		subplan = create_plan_recurse(root, subpath, CP_EXACT_TLIST);
  
  		/* Compute sort column info, and adjust subplan's tlist as needed */
  		subplan = prepare_sort_from_pathkeys(subplan, pathkeys,
  											 subpath->parent->relids,
  											 node->sortColIdx,
  											 false,
  											 &numsortkeys,
  											 &sortColIdx,
  											 &sortOperators,
  											 &collations,
  											 &nullsFirst);
  
  		/*
  		 * Check that we got the same sort key information.  We just Assert
  		 * that the sortops match, since those depend only on the pathkeys;
  		 * but it seems like a good idea to check the sort column numbers
  		 * explicitly, to ensure the tlists really do match up.
  		 */
  		Assert(numsortkeys == node->numCols);
  		if (memcmp(sortColIdx, node->sortColIdx,
  				   numsortkeys * sizeof(AttrNumber)) != 0)
  			elog(ERROR, "MergeAppend child's targetlist doesn't match MergeAppend");
  		Assert(memcmp(sortOperators, node->sortOperators,
  					  numsortkeys * sizeof(Oid)) == 0);
  		Assert(memcmp(collations, node->collations,
  					  numsortkeys * sizeof(Oid)) == 0);
  		Assert(memcmp(nullsFirst, node->nullsFirst,
  					  numsortkeys * sizeof(bool)) == 0);
  
  		/* Now, insert a Sort node if subplan isn't sufficiently ordered */
  		if (!pathkeys_contained_in(pathkeys, subpath->pathkeys))
  		{
  			Sort	   *sort = make_sort(subplan, numsortkeys,
  										 sortColIdx, sortOperators,
  										 collations, nullsFirst);
  
  			label_sort_with_costsize(root, sort, best_path->limit_tuples);
  			subplan = (Plan *) sort;
  		}
  
  		subplans = lappend(subplans, subplan);
  	}
  
  	/*
  	 * If any quals exist, they may be useful to perform further partition
  	 * pruning during execution.  Gather information needed by the executor to
  	 * do partition pruning.
  	 */
  	if (enable_partition_pruning &&
  		rel->reloptkind == RELOPT_BASEREL &&
  		best_path->partitioned_rels != NIL)
  	{
  		List	   *prunequal;
  
  		prunequal = extract_actual_clauses(rel->baserestrictinfo, false);
  
  		if (best_path->path.param_info)
  		{
  			List	   *prmquals = best_path->path.param_info->ppi_clauses;
  
  			prmquals = extract_actual_clauses(prmquals, false);
  			prmquals = (List *) replace_nestloop_params(root,
  														(Node *) prmquals);
  
  			prunequal = list_concat(prunequal, prmquals);
  		}
  
  		if (prunequal != NIL)
  			partpruneinfo = make_partition_pruneinfo(root, rel,
  													 best_path->subpaths,
  													 best_path->partitioned_rels,
  													 prunequal);
  	}
  
  	node->mergeplans = subplans;
  	node->part_prune_info = partpruneinfo;
  
  	/*
  	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
  	 * produce either the exact tlist or a narrow tlist, we should get rid of
  	 * the sort columns again.  We must inject a projection node to do so.
  	 */
  	if (tlist_was_changed && (flags & (CP_EXACT_TLIST | CP_SMALL_TLIST)))
  	{
  		tlist = list_truncate(list_copy(plan->targetlist), orig_tlist_length);
  		return inject_projection_plan(plan, tlist, plan->parallel_safe);
  	}
  	else
  		return plan;
  }
  
  /*
   * create_group_result_plan
   *	  Create a Result plan for 'best_path'.
   *	  This is only used for degenerate grouping cases.
   *
   *	  Returns a Plan node.
   */
  static Result *
  create_group_result_plan(PlannerInfo *root, GroupResultPath *best_path)
  {
  	Result	   *plan;
  	List	   *tlist;
  	List	   *quals;
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	/* best_path->quals is just bare clauses */
  	quals = order_qual_clauses(root, best_path->quals);
  
  	plan = make_result(tlist, (Node *) quals, NULL);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_project_set_plan
   *	  Create a ProjectSet plan for 'best_path'.
   *
   *	  Returns a Plan node.
   */
  static ProjectSet *
  create_project_set_plan(PlannerInfo *root, ProjectSetPath *best_path)
  {
  	ProjectSet *plan;
  	Plan	   *subplan;
  	List	   *tlist;
  
  	/* Since we intend to project, we don't need to constrain child tlist */
  	subplan = create_plan_recurse(root, best_path->subpath, 0);
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	plan = make_project_set(tlist, subplan);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_material_plan
   *	  Create a Material plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   *
   *	  Returns a Plan node.
   */
  static Material *
  create_material_plan(PlannerInfo *root, MaterialPath *best_path, int flags)
  {
  	Material   *plan;
  	Plan	   *subplan;
  
  	/*
  	 * We don't want any excess columns in the materialized tuples, so request
  	 * a smaller tlist.  Otherwise, since Material doesn't project, tlist
  	 * requirements pass through.
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath,
  								  flags | CP_SMALL_TLIST);
  
  	plan = make_material(subplan);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_unique_plan
   *	  Create a Unique plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   *
   *	  Returns a Plan node.
   */
  static Plan *
  create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
  {
  	Plan	   *plan;
  	Plan	   *subplan;
  	List	   *in_operators;
  	List	   *uniq_exprs;
  	List	   *newtlist;
  	int			nextresno;
  	bool		newitems;
  	int			numGroupCols;
  	AttrNumber *groupColIdx;
  	Oid		   *groupCollations;
  	int			groupColPos;
  	ListCell   *l;
  
  	/* Unique doesn't project, so tlist requirements pass through */
  	subplan = create_plan_recurse(root, best_path->subpath, flags);
  
  	/* Done if we don't need to do any actual unique-ifying */
  	if (best_path->umethod == UNIQUE_PATH_NOOP)
  		return subplan;
  
  	/*
  	 * As constructed, the subplan has a "flat" tlist containing just the Vars
  	 * needed here and at upper levels.  The values we are supposed to
  	 * unique-ify may be expressions in these variables.  We have to add any
  	 * such expressions to the subplan's tlist.
  	 *
  	 * The subplan may have a "physical" tlist if it is a simple scan plan. If
  	 * we're going to sort, this should be reduced to the regular tlist, so
  	 * that we don't sort more data than we need to.  For hashing, the tlist
  	 * should be left as-is if we don't need to add any expressions; but if we
  	 * do have to add expressions, then a projection step will be needed at
  	 * runtime anyway, so we may as well remove unneeded items. Therefore
  	 * newtlist starts from build_path_tlist() not just a copy of the
  	 * subplan's tlist; and we don't install it into the subplan unless we are
  	 * sorting or stuff has to be added.
  	 */
  	in_operators = best_path->in_operators;
  	uniq_exprs = best_path->uniq_exprs;
  
  	/* initialize modified subplan tlist as just the "required" vars */
  	newtlist = build_path_tlist(root, &best_path->path);
  	nextresno = list_length(newtlist) + 1;
  	newitems = false;
  
  	foreach(l, uniq_exprs)
  	{
  		Expr	   *uniqexpr = lfirst(l);
  		TargetEntry *tle;
  
  		tle = tlist_member(uniqexpr, newtlist);
  		if (!tle)
  		{
  			tle = makeTargetEntry((Expr *) uniqexpr,
  								  nextresno,
  								  NULL,
  								  false);
  			newtlist = lappend(newtlist, tle);
  			nextresno++;
  			newitems = true;
  		}
  	}
  
  	/* Use change_plan_targetlist in case we need to insert a Result node */
  	if (newitems || best_path->umethod == UNIQUE_PATH_SORT)
  		subplan = change_plan_targetlist(subplan, newtlist,
  										 best_path->path.parallel_safe);
  
  	/*
  	 * Build control information showing which subplan output columns are to
  	 * be examined by the grouping step.  Unfortunately we can't merge this
  	 * with the previous loop, since we didn't then know which version of the
  	 * subplan tlist we'd end up using.
  	 */
  	newtlist = subplan->targetlist;
  	numGroupCols = list_length(uniq_exprs);
  	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
  	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
  
  	groupColPos = 0;
  	foreach(l, uniq_exprs)
  	{
  		Expr	   *uniqexpr = lfirst(l);
  		TargetEntry *tle;
  
  		tle = tlist_member(uniqexpr, newtlist);
  		if (!tle)				/* shouldn't happen */
  			elog(ERROR, "failed to find unique expression in subplan tlist");
  		groupColIdx[groupColPos] = tle->resno;
  		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
  		groupColPos++;
  	}
  
  	if (best_path->umethod == UNIQUE_PATH_HASH)
  	{
  		Oid		   *groupOperators;
  
  		/*
  		 * Get the hashable equality operators for the Agg node to use.
  		 * Normally these are the same as the IN clause operators, but if
  		 * those are cross-type operators then the equality operators are the
  		 * ones for the IN clause operators' RHS datatype.
  		 */
  		groupOperators = (Oid *) palloc(numGroupCols * sizeof(Oid));
  		groupColPos = 0;
  		foreach(l, in_operators)
  		{
  			Oid			in_oper = lfirst_oid(l);
  			Oid			eq_oper;
  
  			if (!get_compatible_hash_operators(in_oper, NULL, &eq_oper))
  				elog(ERROR, "could not find compatible hash operator for operator %u",
  					 in_oper);
  			groupOperators[groupColPos++] = eq_oper;
  		}
  
  		/*
  		 * Since the Agg node is going to project anyway, we can give it the
  		 * minimum output tlist, without any stuff we might have added to the
  		 * subplan tlist.
  		 */
  		plan = (Plan *) make_agg(build_path_tlist(root, &best_path->path),
  								 NIL,
  								 AGG_HASHED,
  								 AGGSPLIT_SIMPLE,
  								 numGroupCols,
  								 groupColIdx,
  								 groupOperators,
  								 groupCollations,
  								 NIL,
  								 NIL,
  								 best_path->path.rows,
  								 subplan);
  	}
  	else
  	{
  		List	   *sortList = NIL;
  		Sort	   *sort;
  
  		/* Create an ORDER BY list to sort the input compatibly */
  		groupColPos = 0;
  		foreach(l, in_operators)
  		{
  			Oid			in_oper = lfirst_oid(l);
  			Oid			sortop;
  			Oid			eqop;
  			TargetEntry *tle;
  			SortGroupClause *sortcl;
  
  			sortop = get_ordering_op_for_equality_op(in_oper, false);
  			if (!OidIsValid(sortop))	/* shouldn't happen */
  				elog(ERROR, "could not find ordering operator for equality operator %u",
  					 in_oper);
  
  			/*
  			 * The Unique node will need equality operators.  Normally these
  			 * are the same as the IN clause operators, but if those are
  			 * cross-type operators then the equality operators are the ones
  			 * for the IN clause operators' RHS datatype.
  			 */
  			eqop = get_equality_op_for_ordering_op(sortop, NULL);
  			if (!OidIsValid(eqop))	/* shouldn't happen */
  				elog(ERROR, "could not find equality operator for ordering operator %u",
  					 sortop);
  
  			tle = get_tle_by_resno(subplan->targetlist,
  								   groupColIdx[groupColPos]);
  			Assert(tle != NULL);
  
  			sortcl = makeNode(SortGroupClause);
  			sortcl->tleSortGroupRef = assignSortGroupRef(tle,
  														 subplan->targetlist);
  			sortcl->eqop = eqop;
  			sortcl->sortop = sortop;
  			sortcl->nulls_first = false;
  			sortcl->hashable = false;	/* no need to make this accurate */
  			sortList = lappend(sortList, sortcl);
  			groupColPos++;
  		}
  		sort = make_sort_from_sortclauses(sortList, subplan);
  		label_sort_with_costsize(root, sort, -1.0);
  		plan = (Plan *) make_unique_from_sortclauses((Plan *) sort, sortList);
  	}
  
  	/* Copy cost data from Path to Plan */
  	copy_generic_path_info(plan, &best_path->path);
  
  	return plan;
  }
  
  /*
   * create_gather_plan
   *
   *	  Create a Gather plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Gather *
  create_gather_plan(PlannerInfo *root, GatherPath *best_path)
  {
  	Gather	   *gather_plan;
  	Plan	   *subplan;
  	List	   *tlist;
  
  	/*
  	 * Although the Gather node can project, we prefer to push down such work
  	 * to its child node, so demand an exact tlist from the child.
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath, CP_EXACT_TLIST);
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	gather_plan = make_gather(tlist,
  							  NIL,
  							  best_path->num_workers,
  							  assign_special_exec_param(root),
  							  best_path->single_copy,
  							  subplan);
  
  	copy_generic_path_info(&gather_plan->plan, &best_path->path);
  
  	/* use parallel mode for parallel plans. */
  	root->glob->parallelModeNeeded = true;
  
  	return gather_plan;
  }
  
  /*
   * create_gather_merge_plan
   *
   *	  Create a Gather Merge plan for 'best_path' and (recursively)
   *	  plans for its subpaths.
   */
  static GatherMerge *
  create_gather_merge_plan(PlannerInfo *root, GatherMergePath *best_path)
  {
  	GatherMerge *gm_plan;
  	Plan	   *subplan;
  	List	   *pathkeys = best_path->path.pathkeys;
  	List	   *tlist = build_path_tlist(root, &best_path->path);
  
  	/* As with Gather, it's best to project away columns in the workers. */
  	subplan = create_plan_recurse(root, best_path->subpath, CP_EXACT_TLIST);
  
  	/* Create a shell for a GatherMerge plan. */
  	gm_plan = makeNode(GatherMerge);
  	gm_plan->plan.targetlist = tlist;
  	gm_plan->num_workers = best_path->num_workers;
  	copy_generic_path_info(&gm_plan->plan, &best_path->path);
  
  	/* Assign the rescan Param. */
  	gm_plan->rescan_param = assign_special_exec_param(root);
  
  	/* Gather Merge is pointless with no pathkeys; use Gather instead. */
  	Assert(pathkeys != NIL);
  
  	/* Compute sort column info, and adjust subplan's tlist as needed */
  	subplan = prepare_sort_from_pathkeys(subplan, pathkeys,
  										 best_path->subpath->parent->relids,
  										 gm_plan->sortColIdx,
  										 false,
  										 &gm_plan->numCols,
  										 &gm_plan->sortColIdx,
  										 &gm_plan->sortOperators,
  										 &gm_plan->collations,
  										 &gm_plan->nullsFirst);
  
  
  	/* Now, insert a Sort node if subplan isn't sufficiently ordered */
  	if (!pathkeys_contained_in(pathkeys, best_path->subpath->pathkeys))
  		subplan = (Plan *) make_sort(subplan, gm_plan->numCols,
  									 gm_plan->sortColIdx,
  									 gm_plan->sortOperators,
  									 gm_plan->collations,
  									 gm_plan->nullsFirst);
  
  	/* Now insert the subplan under GatherMerge. */
  	gm_plan->plan.lefttree = subplan;
  
  	/* use parallel mode for parallel plans. */
  	root->glob->parallelModeNeeded = true;
  
  	return gm_plan;
  }
  
  /*
   * create_projection_plan
   *
   *	  Create a plan tree to do a projection step and (recursively) plans
   *	  for its subpaths.  We may need a Result node for the projection,
   *	  but sometimes we can just let the subplan do the work.
   */
  static Plan *
  create_projection_plan(PlannerInfo *root, ProjectionPath *best_path, int flags)
  {
  	Plan	   *plan;
  	Plan	   *subplan;
  	List	   *tlist;
  	bool		needs_result_node = false;
  
  	/*
  	 * Convert our subpath to a Plan and determine whether we need a Result
  	 * node.
  	 *
  	 * In most cases where we don't need to project, creation_projection_path
  	 * will have set dummypp, but not always.  First, some createplan.c
  	 * routines change the tlists of their nodes.  (An example is that
  	 * create_merge_append_plan might add resjunk sort columns to a
  	 * MergeAppend.)  Second, create_projection_path has no way of knowing
  	 * what path node will be placed on top of the projection path and
  	 * therefore can't predict whether it will require an exact tlist. For
  	 * both of these reasons, we have to recheck here.
  	 */
  	if (use_physical_tlist(root, &best_path->path, flags))
  	{
  		/*
  		 * Our caller doesn't really care what tlist we return, so we don't
  		 * actually need to project.  However, we may still need to ensure
  		 * proper sortgroupref labels, if the caller cares about those.
  		 */
  		subplan = create_plan_recurse(root, best_path->subpath, 0);
  		tlist = subplan->targetlist;
  		if (flags & CP_LABEL_TLIST)
  			apply_pathtarget_labeling_to_tlist(tlist,
  											   best_path->path.pathtarget);
  	}
  	else if (is_projection_capable_path(best_path->subpath))
  	{
  		/*
  		 * Our caller requires that we return the exact tlist, but no separate
  		 * result node is needed because the subpath is projection-capable.
  		 * Tell create_plan_recurse that we're going to ignore the tlist it
  		 * produces.
  		 */
  		subplan = create_plan_recurse(root, best_path->subpath,
  									  CP_IGNORE_TLIST);
  		Assert(is_projection_capable_plan(subplan));
  		tlist = build_path_tlist(root, &best_path->path);
  	}
  	else
  	{
  		/*
  		 * It looks like we need a result node, unless by good fortune the
  		 * requested tlist is exactly the one the child wants to produce.
  		 */
  		subplan = create_plan_recurse(root, best_path->subpath, 0);
  		tlist = build_path_tlist(root, &best_path->path);
  		needs_result_node = !tlist_same_exprs(tlist, subplan->targetlist);
  	}
  
  	/*
  	 * If we make a different decision about whether to include a Result node
  	 * than create_projection_path did, we'll have made slightly wrong cost
  	 * estimates; but label the plan with the cost estimates we actually used,
  	 * not "corrected" ones.  (XXX this could be cleaned up if we moved more
  	 * of the sortcolumn setup logic into Path creation, but that would add
  	 * expense to creating Paths we might end up not using.)
  	 */
  	if (!needs_result_node)
  	{
  		/* Don't need a separate Result, just assign tlist to subplan */
  		plan = subplan;
  		plan->targetlist = tlist;
  
  		/* Label plan with the estimated costs we actually used */
  		plan->startup_cost = best_path->path.startup_cost;
  		plan->total_cost = best_path->path.total_cost;
  		plan->plan_rows = best_path->path.rows;
  		plan->plan_width = best_path->path.pathtarget->width;
  		plan->parallel_safe = best_path->path.parallel_safe;
  		/* ... but don't change subplan's parallel_aware flag */
  	}
  	else
  	{
  		/* We need a Result node */
  		plan = (Plan *) make_result(tlist, NULL, subplan);
  
  		copy_generic_path_info(plan, (Path *) best_path);
  	}
  
  	return plan;
  }
  
  /*
   * inject_projection_plan
   *	  Insert a Result node to do a projection step.
   *
   * This is used in a few places where we decide on-the-fly that we need a
   * projection step as part of the tree generated for some Path node.
   * We should try to get rid of this in favor of doing it more honestly.
   *
   * One reason it's ugly is we have to be told the right parallel_safe marking
   * to apply (since the tlist might be unsafe even if the child plan is safe).
   */
  static Plan *
  inject_projection_plan(Plan *subplan, List *tlist, bool parallel_safe)
  {
  	Plan	   *plan;
  
  	plan = (Plan *) make_result(tlist, NULL, subplan);
  
  	/*
  	 * In principle, we should charge tlist eval cost plus cpu_per_tuple per
  	 * row for the Result node.  But the former has probably been factored in
  	 * already and the latter was not accounted for during Path construction,
  	 * so being formally correct might just make the EXPLAIN output look less
  	 * consistent not more so.  Hence, just copy the subplan's cost.
  	 */
  	copy_plan_costsize(plan, subplan);
  	plan->parallel_safe = parallel_safe;
  
  	return plan;
  }
  
  /*
   * change_plan_targetlist
   *	  Externally available wrapper for inject_projection_plan.
   *
   * This is meant for use by FDW plan-generation functions, which might
   * want to adjust the tlist computed by some subplan tree.  In general,
   * a Result node is needed to compute the new tlist, but we can optimize
   * some cases.
   *
   * In most cases, tlist_parallel_safe can just be passed as the parallel_safe
   * flag of the FDW's own Path node.
   */
  Plan *
  change_plan_targetlist(Plan *subplan, List *tlist, bool tlist_parallel_safe)
  {
  	/*
  	 * If the top plan node can't do projections and its existing target list
  	 * isn't already what we need, we need to add a Result node to help it
  	 * along.
  	 */
  	if (!is_projection_capable_plan(subplan) &&
  		!tlist_same_exprs(tlist, subplan->targetlist))
  		subplan = inject_projection_plan(subplan, tlist,
  										 subplan->parallel_safe &&
  										 tlist_parallel_safe);
  	else
  	{
  		/* Else we can just replace the plan node's tlist */
  		subplan->targetlist = tlist;
  		subplan->parallel_safe &= tlist_parallel_safe;
  	}
  	return subplan;
  }
  
  /*
   * create_sort_plan
   *
   *	  Create a Sort plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Sort *
  create_sort_plan(PlannerInfo *root, SortPath *best_path, int flags)
  {
  	Sort	   *plan;
  	Plan	   *subplan;
  
  	/*
  	 * We don't want any excess columns in the sorted tuples, so request a
  	 * smaller tlist.  Otherwise, since Sort doesn't project, tlist
  	 * requirements pass through.
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath,
  								  flags | CP_SMALL_TLIST);
  
  	/*
  	 * make_sort_from_pathkeys() indirectly calls find_ec_member_for_tle(),
  	 * which will ignore any child EC members that don't belong to the given
  	 * relids. Thus, if this sort path is based on a child relation, we must
  	 * pass its relids.
  	 */
  	plan = make_sort_from_pathkeys(subplan, best_path->path.pathkeys,
  								   IS_OTHER_REL(best_path->subpath->parent) ?
  								   best_path->path.parent->relids : NULL);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_group_plan
   *
   *	  Create a Group plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Group *
  create_group_plan(PlannerInfo *root, GroupPath *best_path)
  {
  	Group	   *plan;
  	Plan	   *subplan;
  	List	   *tlist;
  	List	   *quals;
  
  	/*
  	 * Group can project, so no need to be terribly picky about child tlist,
  	 * but we do need grouping columns to be available
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath, CP_LABEL_TLIST);
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	quals = order_qual_clauses(root, best_path->qual);
  
  	plan = make_group(tlist,
  					  quals,
  					  list_length(best_path->groupClause),
  					  extract_grouping_cols(best_path->groupClause,
  											subplan->targetlist),
  					  extract_grouping_ops(best_path->groupClause),
  					  extract_grouping_collations(best_path->groupClause,
  												  subplan->targetlist),
  					  subplan);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_upper_unique_plan
   *
   *	  Create a Unique plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Unique *
  create_upper_unique_plan(PlannerInfo *root, UpperUniquePath *best_path, int flags)
  {
  	Unique	   *plan;
  	Plan	   *subplan;
  
  	/*
  	 * Unique doesn't project, so tlist requirements pass through; moreover we
  	 * need grouping columns to be labeled.
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath,
  								  flags | CP_LABEL_TLIST);
  
  	plan = make_unique_from_pathkeys(subplan,
  									 best_path->path.pathkeys,
  									 best_path->numkeys);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_agg_plan
   *
   *	  Create an Agg plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Agg *
  create_agg_plan(PlannerInfo *root, AggPath *best_path)
  {
  	Agg		   *plan;
  	Plan	   *subplan;
  	List	   *tlist;
  	List	   *quals;
  
  	/*
  	 * Agg can project, so no need to be terribly picky about child tlist, but
  	 * we do need grouping columns to be available
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath, CP_LABEL_TLIST);
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	quals = order_qual_clauses(root, best_path->qual);
  
  	plan = make_agg(tlist, quals,
  					best_path->aggstrategy,
  					best_path->aggsplit,
  					list_length(best_path->groupClause),
  					extract_grouping_cols(best_path->groupClause,
  										  subplan->targetlist),
  					extract_grouping_ops(best_path->groupClause),
  					extract_grouping_collations(best_path->groupClause,
  												subplan->targetlist),
  					NIL,
  					NIL,
  					best_path->numGroups,
  					subplan);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * Given a groupclause for a collection of grouping sets, produce the
   * corresponding groupColIdx.
   *
   * root->grouping_map maps the tleSortGroupRef to the actual column position in
   * the input tuple. So we get the ref from the entries in the groupclause and
   * look them up there.
   */
  static AttrNumber *
  remap_groupColIdx(PlannerInfo *root, List *groupClause)
  {
  	AttrNumber *grouping_map = root->grouping_map;
  	AttrNumber *new_grpColIdx;
  	ListCell   *lc;
  	int			i;
  
  	Assert(grouping_map);
  
  	new_grpColIdx = palloc0(sizeof(AttrNumber) * list_length(groupClause));
  
  	i = 0;
  	foreach(lc, groupClause)
  	{
  		SortGroupClause *clause = lfirst(lc);
  
  		new_grpColIdx[i++] = grouping_map[clause->tleSortGroupRef];
  	}
  
  	return new_grpColIdx;
  }
  
  /*
   * create_groupingsets_plan
   *	  Create a plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   *
   *	  What we emit is an Agg plan with some vestigial Agg and Sort nodes
   *	  hanging off the side.  The top Agg implements the last grouping set
   *	  specified in the GroupingSetsPath, and any additional grouping sets
   *	  each give rise to a subsidiary Agg and Sort node in the top Agg's
   *	  "chain" list.  These nodes don't participate in the plan directly,
   *	  but they are a convenient way to represent the required data for
   *	  the extra steps.
   *
   *	  Returns a Plan node.
   */
  static Plan *
  create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
  {
  	Agg		   *plan;
  	Plan	   *subplan;
  	List	   *rollups = best_path->rollups;
  	AttrNumber *grouping_map;
  	int			maxref;
  	List	   *chain;
  	ListCell   *lc;
  
  	/* Shouldn't get here without grouping sets */
  	Assert(root->parse->groupingSets);
  	Assert(rollups != NIL);
  
  	/*
  	 * Agg can project, so no need to be terribly picky about child tlist, but
  	 * we do need grouping columns to be available
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath, CP_LABEL_TLIST);
  
  	/*
  	 * Compute the mapping from tleSortGroupRef to column index in the child's
  	 * tlist.  First, identify max SortGroupRef in groupClause, for array
  	 * sizing.
  	 */
  	maxref = 0;
  	foreach(lc, root->parse->groupClause)
  	{
  		SortGroupClause *gc = (SortGroupClause *) lfirst(lc);
  
  		if (gc->tleSortGroupRef > maxref)
  			maxref = gc->tleSortGroupRef;
  	}
  
  	grouping_map = (AttrNumber *) palloc0((maxref + 1) * sizeof(AttrNumber));
  
  	/* Now look up the column numbers in the child's tlist */
  	foreach(lc, root->parse->groupClause)
  	{
  		SortGroupClause *gc = (SortGroupClause *) lfirst(lc);
  		TargetEntry *tle = get_sortgroupclause_tle(gc, subplan->targetlist);
  
  		grouping_map[gc->tleSortGroupRef] = tle->resno;
  	}
  
  	/*
  	 * During setrefs.c, we'll need the grouping_map to fix up the cols lists
  	 * in GroupingFunc nodes.  Save it for setrefs.c to use.
  	 *
  	 * This doesn't work if we're in an inheritance subtree (see notes in
  	 * create_modifytable_plan).  Fortunately we can't be because there would
  	 * never be grouping in an UPDATE/DELETE; but let's Assert that.
  	 */
  	Assert(root->inhTargetKind == INHKIND_NONE);
  	Assert(root->grouping_map == NULL);
  	root->grouping_map = grouping_map;
  
  	/*
  	 * Generate the side nodes that describe the other sort and group
  	 * operations besides the top one.  Note that we don't worry about putting
  	 * accurate cost estimates in the side nodes; only the topmost Agg node's
  	 * costs will be shown by EXPLAIN.
  	 */
  	chain = NIL;
  	if (list_length(rollups) > 1)
  	{
  		ListCell   *lc2 = lnext(list_head(rollups));
  		bool		is_first_sort = ((RollupData *) linitial(rollups))->is_hashed;
  
  		for_each_cell(lc, lc2)
  		{
  			RollupData *rollup = lfirst(lc);
  			AttrNumber *new_grpColIdx;
  			Plan	   *sort_plan = NULL;
  			Plan	   *agg_plan;
  			AggStrategy strat;
  
  			new_grpColIdx = remap_groupColIdx(root, rollup->groupClause);
  
  			if (!rollup->is_hashed && !is_first_sort)
  			{
  				sort_plan = (Plan *)
  					make_sort_from_groupcols(rollup->groupClause,
  											 new_grpColIdx,
  											 subplan);
  			}
  
  			if (!rollup->is_hashed)
  				is_first_sort = false;
  
  			if (rollup->is_hashed)
  				strat = AGG_HASHED;
  			else if (list_length(linitial(rollup->gsets)) == 0)
  				strat = AGG_PLAIN;
  			else
  				strat = AGG_SORTED;
  
  			agg_plan = (Plan *) make_agg(NIL,
  										 NIL,
  										 strat,
  										 AGGSPLIT_SIMPLE,
  										 list_length((List *) linitial(rollup->gsets)),
  										 new_grpColIdx,
  										 extract_grouping_ops(rollup->groupClause),
  										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
  										 rollup->gsets,
  										 NIL,
  										 rollup->numGroups,
  										 sort_plan);
  
  			/*
  			 * Remove stuff we don't need to avoid bloating debug output.
  			 */
  			if (sort_plan)
  			{
  				sort_plan->targetlist = NIL;
  				sort_plan->lefttree = NULL;
  			}
  
  			chain = lappend(chain, agg_plan);
  		}
  	}
  
  	/*
  	 * Now make the real Agg node
  	 */
  	{
  		RollupData *rollup = linitial(rollups);
  		AttrNumber *top_grpColIdx;
  		int			numGroupCols;
  
  		top_grpColIdx = remap_groupColIdx(root, rollup->groupClause);
  
  		numGroupCols = list_length((List *) linitial(rollup->gsets));
  
  		plan = make_agg(build_path_tlist(root, &best_path->path),
  						best_path->qual,
  						best_path->aggstrategy,
  						AGGSPLIT_SIMPLE,
  						numGroupCols,
  						top_grpColIdx,
  						extract_grouping_ops(rollup->groupClause),
  						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
  						rollup->gsets,
  						chain,
  						rollup->numGroups,
  						subplan);
  
  		/* Copy cost data from Path to Plan */
  		copy_generic_path_info(&plan->plan, &best_path->path);
  	}
  
  	return (Plan *) plan;
  }
  
  /*
   * create_minmaxagg_plan
   *
   *	  Create a Result plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Result *
  create_minmaxagg_plan(PlannerInfo *root, MinMaxAggPath *best_path)
  {
  	Result	   *plan;
  	List	   *tlist;
  	ListCell   *lc;
  
  	/* Prepare an InitPlan for each aggregate's subquery. */
  	foreach(lc, best_path->mmaggregates)
  	{
  		MinMaxAggInfo *mminfo = (MinMaxAggInfo *) lfirst(lc);
  		PlannerInfo *subroot = mminfo->subroot;
  		Query	   *subparse = subroot->parse;
  		Plan	   *plan;
  
  		/*
  		 * Generate the plan for the subquery. We already have a Path, but we
  		 * have to convert it to a Plan and attach a LIMIT node above it.
  		 * Since we are entering a different planner context (subroot),
  		 * recurse to create_plan not create_plan_recurse.
  		 */
  		plan = create_plan(subroot, mminfo->path);
  
  		plan = (Plan *) make_limit(plan,
  								   subparse->limitOffset,
  								   subparse->limitCount);
  
  		/* Must apply correct cost/width data to Limit node */
  		plan->startup_cost = mminfo->path->startup_cost;
  		plan->total_cost = mminfo->pathcost;
  		plan->plan_rows = 1;
  		plan->plan_width = mminfo->path->pathtarget->width;
  		plan->parallel_aware = false;
  		plan->parallel_safe = mminfo->path->parallel_safe;
  
  		/* Convert the plan into an InitPlan in the outer query. */
  		SS_make_initplan_from_plan(root, subroot, plan, mminfo->param);
  	}
  
  	/* Generate the output plan --- basically just a Result */
  	tlist = build_path_tlist(root, &best_path->path);
  
  	plan = make_result(tlist, (Node *) best_path->quals, NULL);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	/*
  	 * During setrefs.c, we'll need to replace references to the Agg nodes
  	 * with InitPlan output params.  (We can't just do that locally in the
  	 * MinMaxAgg node, because path nodes above here may have Agg references
  	 * as well.)  Save the mmaggregates list to tell setrefs.c to do that.
  	 *
  	 * This doesn't work if we're in an inheritance subtree (see notes in
  	 * create_modifytable_plan).  Fortunately we can't be because there would
  	 * never be aggregates in an UPDATE/DELETE; but let's Assert that.
  	 */
  	Assert(root->inhTargetKind == INHKIND_NONE);
  	Assert(root->minmax_aggs == NIL);
  	root->minmax_aggs = best_path->mmaggregates;
  
  	return plan;
  }
  
  /*
   * create_windowagg_plan
   *
   *	  Create a WindowAgg plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static WindowAgg *
  create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
  {
  	WindowAgg  *plan;
  	WindowClause *wc = best_path->winclause;
  	int			numPart = list_length(wc->partitionClause);
  	int			numOrder = list_length(wc->orderClause);
  	Plan	   *subplan;
  	List	   *tlist;
  	int			partNumCols;
  	AttrNumber *partColIdx;
  	Oid		   *partOperators;
  	Oid		   *partCollations;
  	int			ordNumCols;
  	AttrNumber *ordColIdx;
  	Oid		   *ordOperators;
  	Oid		   *ordCollations;
  	ListCell   *lc;
  
  	/*
  	 * Choice of tlist here is motivated by the fact that WindowAgg will be
  	 * storing the input rows of window frames in a tuplestore; it therefore
  	 * behooves us to request a small tlist to avoid wasting space. We do of
  	 * course need grouping columns to be available.
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath,
  								  CP_LABEL_TLIST | CP_SMALL_TLIST);
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	/*
  	 * Convert SortGroupClause lists into arrays of attr indexes and equality
  	 * operators, as wanted by executor.  (Note: in principle, it's possible
  	 * to drop some of the sort columns, if they were proved redundant by
  	 * pathkey logic.  However, it doesn't seem worth going out of our way to
  	 * optimize such cases.  In any case, we must *not* remove the ordering
  	 * column for RANGE OFFSET cases, as the executor needs that for in_range
  	 * tests even if it's known to be equal to some partitioning column.)
  	 */
  	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
  	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
  	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
  
  	partNumCols = 0;
  	foreach(lc, wc->partitionClause)
  	{
  		SortGroupClause *sgc = (SortGroupClause *) lfirst(lc);
  		TargetEntry *tle = get_sortgroupclause_tle(sgc, subplan->targetlist);
  
  		Assert(OidIsValid(sgc->eqop));
  		partColIdx[partNumCols] = tle->resno;
  		partOperators[partNumCols] = sgc->eqop;
  		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
  		partNumCols++;
  	}
  
  	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
  	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
  	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
  
  	ordNumCols = 0;
  	foreach(lc, wc->orderClause)
  	{
  		SortGroupClause *sgc = (SortGroupClause *) lfirst(lc);
  		TargetEntry *tle = get_sortgroupclause_tle(sgc, subplan->targetlist);
  
  		Assert(OidIsValid(sgc->eqop));
  		ordColIdx[ordNumCols] = tle->resno;
  		ordOperators[ordNumCols] = sgc->eqop;
  		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
  		ordNumCols++;
  	}
  
  	/* And finally we can make the WindowAgg node */
  	plan = make_windowagg(tlist,
  						  wc->winref,
  						  partNumCols,
  						  partColIdx,
  						  partOperators,
  						  partCollations,
  						  ordNumCols,
  						  ordColIdx,
  						  ordOperators,
  						  ordCollations,
  						  wc->frameOptions,
  						  wc->startOffset,
  						  wc->endOffset,
  						  wc->startInRangeFunc,
  						  wc->endInRangeFunc,
  						  wc->inRangeColl,
  						  wc->inRangeAsc,
  						  wc->inRangeNullsFirst,
  						  subplan);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_setop_plan
   *
   *	  Create a SetOp plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static SetOp *
  create_setop_plan(PlannerInfo *root, SetOpPath *best_path, int flags)
  {
  	SetOp	   *plan;
  	Plan	   *subplan;
  	long		numGroups;
  
  	/*
  	 * SetOp doesn't project, so tlist requirements pass through; moreover we
  	 * need grouping columns to be labeled.
  	 */
  	subplan = create_plan_recurse(root, best_path->subpath,
  								  flags | CP_LABEL_TLIST);
  
  	/* Convert numGroups to long int --- but 'ware overflow! */
  	numGroups = (long) Min(best_path->numGroups, (double) LONG_MAX);
  
  	plan = make_setop(best_path->cmd,
  					  best_path->strategy,
  					  subplan,
  					  best_path->distinctList,
  					  best_path->flagColIdx,
  					  best_path->firstFlag,
  					  numGroups);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_recursiveunion_plan
   *
   *	  Create a RecursiveUnion plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static RecursiveUnion *
  create_recursiveunion_plan(PlannerInfo *root, RecursiveUnionPath *best_path)
  {
  	RecursiveUnion *plan;
  	Plan	   *leftplan;
  	Plan	   *rightplan;
  	List	   *tlist;
  	long		numGroups;
  
  	/* Need both children to produce same tlist, so force it */
  	leftplan = create_plan_recurse(root, best_path->leftpath, CP_EXACT_TLIST);
  	rightplan = create_plan_recurse(root, best_path->rightpath, CP_EXACT_TLIST);
  
  	tlist = build_path_tlist(root, &best_path->path);
  
  	/* Convert numGroups to long int --- but 'ware overflow! */
  	numGroups = (long) Min(best_path->numGroups, (double) LONG_MAX);
  
  	plan = make_recursive_union(tlist,
  								leftplan,
  								rightplan,
  								best_path->wtParam,
  								best_path->distinctList,
  								numGroups);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_lockrows_plan
   *
   *	  Create a LockRows plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static LockRows *
  create_lockrows_plan(PlannerInfo *root, LockRowsPath *best_path,
  					 int flags)
  {
  	LockRows   *plan;
  	Plan	   *subplan;
  
  	/* LockRows doesn't project, so tlist requirements pass through */
  	subplan = create_plan_recurse(root, best_path->subpath, flags);
  
  	plan = make_lockrows(subplan, best_path->rowMarks, best_path->epqParam);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  /*
   * create_modifytable_plan
   *	  Create a ModifyTable plan for 'best_path'.
   *
   *	  Returns a Plan node.
   */
  static ModifyTable *
  create_modifytable_plan(PlannerInfo *root, ModifyTablePath *best_path)
  {
  	ModifyTable *plan;
  	List	   *subplans = NIL;
  	ListCell   *subpaths,
  			   *subroots;
  
  	/* Build the plan for each input path */
  	forboth(subpaths, best_path->subpaths,
  			subroots, best_path->subroots)
  	{
  		Path	   *subpath = (Path *) lfirst(subpaths);
  		PlannerInfo *subroot = (PlannerInfo *) lfirst(subroots);
  		Plan	   *subplan;
  
  		/*
  		 * In an inherited UPDATE/DELETE, reference the per-child modified
  		 * subroot while creating Plans from Paths for the child rel.  This is
  		 * a kluge, but otherwise it's too hard to ensure that Plan creation
  		 * functions (particularly in FDWs) don't depend on the contents of
  		 * "root" matching what they saw at Path creation time.  The main
  		 * downside is that creation functions for Plans that might appear
  		 * below a ModifyTable cannot expect to modify the contents of "root"
  		 * and have it "stick" for subsequent processing such as setrefs.c.
  		 * That's not great, but it seems better than the alternative.
  		 */
  		subplan = create_plan_recurse(subroot, subpath, CP_EXACT_TLIST);
  
  		/* Transfer resname/resjunk labeling, too, to keep executor happy */
  		apply_tlist_labeling(subplan->targetlist, subroot->processed_tlist);
  
  		subplans = lappend(subplans, subplan);
  	}
  
  	plan = make_modifytable(root,
  							best_path->operation,
  							best_path->canSetTag,
  							best_path->nominalRelation,
  							best_path->rootRelation,
  							best_path->partColsUpdated,
  							best_path->resultRelations,
  							subplans,
  							best_path->subroots,
  							best_path->withCheckOptionLists,
  							best_path->returningLists,
  							best_path->rowMarks,
  							best_path->onconflict,
  							best_path->epqParam);
  
  	copy_generic_path_info(&plan->plan, &best_path->path);
  
  	return plan;
  }
  
  /*
   * create_limit_plan
   *
   *	  Create a Limit plan for 'best_path' and (recursively) plans
   *	  for its subpaths.
   */
  static Limit *
  create_limit_plan(PlannerInfo *root, LimitPath *best_path, int flags)
  {
  	Limit	   *plan;
  	Plan	   *subplan;
  
  	/* Limit doesn't project, so tlist requirements pass through */
  	subplan = create_plan_recurse(root, best_path->subpath, flags);
  
  	plan = make_limit(subplan,
  					  best_path->limitOffset,
  					  best_path->limitCount);
  
  	copy_generic_path_info(&plan->plan, (Path *) best_path);
  
  	return plan;
  }
  
  
  /*****************************************************************************
   *
   *	BASE-RELATION SCAN METHODS
   *
   *****************************************************************************/
  
  
  /*
   * create_seqscan_plan
   *	 Returns a seqscan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static SeqScan *
  create_seqscan_plan(PlannerInfo *root, Path *best_path,
  					List *tlist, List *scan_clauses)
  {
  	SeqScan    *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  
  	/* it should be a base rel... */
  	Assert(scan_relid > 0);
  	Assert(best_path->parent->rtekind == RTE_RELATION);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  	}
  
  	scan_plan = make_seqscan(tlist,
  							 scan_clauses,
  							 scan_relid);
  
  	copy_generic_path_info(&scan_plan->plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_samplescan_plan
   *	 Returns a samplescan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static SampleScan *
  create_samplescan_plan(PlannerInfo *root, Path *best_path,
  					   List *tlist, List *scan_clauses)
  {
  	SampleScan *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  	TableSampleClause *tsc;
  
  	/* it should be a base rel with a tablesample clause... */
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_RELATION);
  	tsc = rte->tablesample;
  	Assert(tsc != NULL);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  		tsc = (TableSampleClause *)
  			replace_nestloop_params(root, (Node *) tsc);
  	}
  
  	scan_plan = make_samplescan(tlist,
  								scan_clauses,
  								scan_relid,
  								tsc);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_indexscan_plan
   *	  Returns an indexscan plan for the base relation scanned by 'best_path'
   *	  with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   *
   * We use this for both plain IndexScans and IndexOnlyScans, because the
   * qual preprocessing work is the same for both.  Note that the caller tells
   * us which to build --- we don't look at best_path->path.pathtype, because
   * create_bitmap_subplan needs to be able to override the prior decision.
   */
  static Scan *
  create_indexscan_plan(PlannerInfo *root,
  					  IndexPath *best_path,
  					  List *tlist,
  					  List *scan_clauses,
  					  bool indexonly)
  {
  	Scan	   *scan_plan;
  	List	   *indexclauses = best_path->indexclauses;
  	List	   *indexorderbys = best_path->indexorderbys;
  	Index		baserelid = best_path->path.parent->relid;
  	Oid			indexoid = best_path->indexinfo->indexoid;
  	List	   *qpqual;
  	List	   *stripped_indexquals;
  	List	   *fixed_indexquals;
  	List	   *fixed_indexorderbys;
  	List	   *indexorderbyops = NIL;
  	ListCell   *l;
  
  	/* it should be a base rel... */
  	Assert(baserelid > 0);
  	Assert(best_path->path.parent->rtekind == RTE_RELATION);
  
  	/*
  	 * Extract the index qual expressions (stripped of RestrictInfos) from the
  	 * IndexClauses list, and prepare a copy with index Vars substituted for
  	 * table Vars.  (This step also does replace_nestloop_params on the
  	 * fixed_indexquals.)
  	 */
  	fix_indexqual_references(root, best_path,
  							 &stripped_indexquals,
  							 &fixed_indexquals);
  
  	/*
  	 * Likewise fix up index attr references in the ORDER BY expressions.
  	 */
  	fixed_indexorderbys = fix_indexorderby_references(root, best_path);
  
  	/*
  	 * The qpqual list must contain all restrictions not automatically handled
  	 * by the index, other than pseudoconstant clauses which will be handled
  	 * by a separate gating plan node.  All the predicates in the indexquals
  	 * will be checked (either by the index itself, or by nodeIndexscan.c),
  	 * but if there are any "special" operators involved then they must be
  	 * included in qpqual.  The upshot is that qpqual must contain
  	 * scan_clauses minus whatever appears in indexquals.
  	 *
  	 * is_redundant_with_indexclauses() detects cases where a scan clause is
  	 * present in the indexclauses list or is generated from the same
  	 * EquivalenceClass as some indexclause, and is therefore redundant with
  	 * it, though not equal.  (The latter happens when indxpath.c prefers a
  	 * different derived equality than what generate_join_implied_equalities
  	 * picked for a parameterized scan's ppi_clauses.)  Note that it will not
  	 * match to lossy index clauses, which is critical because we have to
  	 * include the original clause in qpqual in that case.
  	 *
  	 * In some situations (particularly with OR'd index conditions) we may
  	 * have scan_clauses that are not equal to, but are logically implied by,
  	 * the index quals; so we also try a predicate_implied_by() check to see
  	 * if we can discard quals that way.  (predicate_implied_by assumes its
  	 * first input contains only immutable functions, so we have to check
  	 * that.)
  	 *
  	 * Note: if you change this bit of code you should also look at
  	 * extract_nonindex_conditions() in costsize.c.
  	 */
  	qpqual = NIL;
  	foreach(l, scan_clauses)
  	{
  		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
  
  		if (rinfo->pseudoconstant)
  			continue;			/* we may drop pseudoconstants here */
  		if (is_redundant_with_indexclauses(rinfo, indexclauses))
  			continue;			/* dup or derived from same EquivalenceClass */
  		if (!contain_mutable_functions((Node *) rinfo->clause) &&
  			predicate_implied_by(list_make1(rinfo->clause), stripped_indexquals,
  								 false))
  			continue;			/* provably implied by indexquals */
  		qpqual = lappend(qpqual, rinfo);
  	}
  
  	/* Sort clauses into best execution order */
  	qpqual = order_qual_clauses(root, qpqual);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	qpqual = extract_actual_clauses(qpqual, false);
  
  	/*
  	 * We have to replace any outer-relation variables with nestloop params in
  	 * the indexqualorig, qpqual, and indexorderbyorig expressions.  A bit
  	 * annoying to have to do this separately from the processing in
  	 * fix_indexqual_references --- rethink this when generalizing the inner
  	 * indexscan support.  But note we can't really do this earlier because
  	 * it'd break the comparisons to predicates above ... (or would it?  Those
  	 * wouldn't have outer refs)
  	 */
  	if (best_path->path.param_info)
  	{
  		stripped_indexquals = (List *)
  			replace_nestloop_params(root, (Node *) stripped_indexquals);
  		qpqual = (List *)
  			replace_nestloop_params(root, (Node *) qpqual);
  		indexorderbys = (List *)
  			replace_nestloop_params(root, (Node *) indexorderbys);
  	}
  
  	/*
  	 * If there are ORDER BY expressions, look up the sort operators for their
  	 * result datatypes.
  	 */
  	if (indexorderbys)
  	{
  		ListCell   *pathkeyCell,
  				   *exprCell;
  
  		/*
  		 * PathKey contains OID of the btree opfamily we're sorting by, but
  		 * that's not quite enough because we need the expression's datatype
  		 * to look up the sort operator in the operator family.
  		 */
  		Assert(list_length(best_path->path.pathkeys) == list_length(indexorderbys));
  		forboth(pathkeyCell, best_path->path.pathkeys, exprCell, indexorderbys)
  		{
  			PathKey    *pathkey = (PathKey *) lfirst(pathkeyCell);
  			Node	   *expr = (Node *) lfirst(exprCell);
  			Oid			exprtype = exprType(expr);
  			Oid			sortop;
  
  			/* Get sort operator from opfamily */
  			sortop = get_opfamily_member(pathkey->pk_opfamily,
  										 exprtype,
  										 exprtype,
  										 pathkey->pk_strategy);
  			if (!OidIsValid(sortop))
  				elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
  					 pathkey->pk_strategy, exprtype, exprtype, pathkey->pk_opfamily);
  			indexorderbyops = lappend_oid(indexorderbyops, sortop);
  		}
  	}
  
  	/* Finally ready to build the plan node */
  	if (indexonly)
  		scan_plan = (Scan *) make_indexonlyscan(tlist,
  												qpqual,
  												baserelid,
  												indexoid,
  												fixed_indexquals,
  												fixed_indexorderbys,
  												best_path->indexinfo->indextlist,
  												best_path->indexscandir);
  	else
  		scan_plan = (Scan *) make_indexscan(tlist,
  											qpqual,
  											baserelid,
  											indexoid,
  											fixed_indexquals,
  											stripped_indexquals,
  											fixed_indexorderbys,
  											indexorderbys,
  											indexorderbyops,
  											best_path->indexscandir);
  
  	copy_generic_path_info(&scan_plan->plan, &best_path->path);
  
  	return scan_plan;
  }
  
  /*
   * create_bitmap_scan_plan
   *	  Returns a bitmap scan plan for the base relation scanned by 'best_path'
   *	  with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static BitmapHeapScan *
  create_bitmap_scan_plan(PlannerInfo *root,
  						BitmapHeapPath *best_path,
  						List *tlist,
  						List *scan_clauses)
  {
  	Index		baserelid = best_path->path.parent->relid;
  	Plan	   *bitmapqualplan;
  	List	   *bitmapqualorig;
  	List	   *indexquals;
  	List	   *indexECs;
  	List	   *qpqual;
  	ListCell   *l;
  	BitmapHeapScan *scan_plan;
  
  	/* it should be a base rel... */
  	Assert(baserelid > 0);
  	Assert(best_path->path.parent->rtekind == RTE_RELATION);
  
  	/* Process the bitmapqual tree into a Plan tree and qual lists */
  	bitmapqualplan = create_bitmap_subplan(root, best_path->bitmapqual,
  										   &bitmapqualorig, &indexquals,
  										   &indexECs);
  
  	if (best_path->path.parallel_aware)
  		bitmap_subplan_mark_shared(bitmapqualplan);
  
  	/*
  	 * The qpqual list must contain all restrictions not automatically handled
  	 * by the index, other than pseudoconstant clauses which will be handled
  	 * by a separate gating plan node.  All the predicates in the indexquals
  	 * will be checked (either by the index itself, or by
  	 * nodeBitmapHeapscan.c), but if there are any "special" operators
  	 * involved then they must be added to qpqual.  The upshot is that qpqual
  	 * must contain scan_clauses minus whatever appears in indexquals.
  	 *
  	 * This loop is similar to the comparable code in create_indexscan_plan(),
  	 * but with some differences because it has to compare the scan clauses to
  	 * stripped (no RestrictInfos) indexquals.  See comments there for more
  	 * info.
  	 *
  	 * In normal cases simple equal() checks will be enough to spot duplicate
  	 * clauses, so we try that first.  We next see if the scan clause is
  	 * redundant with any top-level indexqual by virtue of being generated
  	 * from the same EC.  After that, try predicate_implied_by().
  	 *
  	 * Unlike create_indexscan_plan(), the predicate_implied_by() test here is
  	 * useful for getting rid of qpquals that are implied by index predicates,
  	 * because the predicate conditions are included in the "indexquals"
  	 * returned by create_bitmap_subplan().  Bitmap scans have to do it that
  	 * way because predicate conditions need to be rechecked if the scan
  	 * becomes lossy, so they have to be included in bitmapqualorig.
  	 */
  	qpqual = NIL;
  	foreach(l, scan_clauses)
  	{
  		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
  		Node	   *clause = (Node *) rinfo->clause;
  
  		if (rinfo->pseudoconstant)
  			continue;			/* we may drop pseudoconstants here */
  		if (list_member(indexquals, clause))
  			continue;			/* simple duplicate */
  		if (rinfo->parent_ec && list_member_ptr(indexECs, rinfo->parent_ec))
  			continue;			/* derived from same EquivalenceClass */
  		if (!contain_mutable_functions(clause) &&
  			predicate_implied_by(list_make1(clause), indexquals, false))
  			continue;			/* provably implied by indexquals */
  		qpqual = lappend(qpqual, rinfo);
  	}
  
  	/* Sort clauses into best execution order */
  	qpqual = order_qual_clauses(root, qpqual);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	qpqual = extract_actual_clauses(qpqual, false);
  
  	/*
  	 * When dealing with special operators, we will at this point have
  	 * duplicate clauses in qpqual and bitmapqualorig.  We may as well drop
  	 * 'em from bitmapqualorig, since there's no point in making the tests
  	 * twice.
  	 */
  	bitmapqualorig = list_difference_ptr(bitmapqualorig, qpqual);
  
  	/*
  	 * We have to replace any outer-relation variables with nestloop params in
  	 * the qpqual and bitmapqualorig expressions.  (This was already done for
  	 * expressions attached to plan nodes in the bitmapqualplan tree.)
  	 */
  	if (best_path->path.param_info)
  	{
  		qpqual = (List *)
  			replace_nestloop_params(root, (Node *) qpqual);
  		bitmapqualorig = (List *)
  			replace_nestloop_params(root, (Node *) bitmapqualorig);
  	}
  
  	/* Finally ready to build the plan node */
  	scan_plan = make_bitmap_heapscan(tlist,
  									 qpqual,
  									 bitmapqualplan,
  									 bitmapqualorig,
  									 baserelid);
  
  	copy_generic_path_info(&scan_plan->scan.plan, &best_path->path);
  
  	return scan_plan;
  }
  
  /*
   * Given a bitmapqual tree, generate the Plan tree that implements it
   *
   * As byproducts, we also return in *qual and *indexqual the qual lists
   * (in implicit-AND form, without RestrictInfos) describing the original index
   * conditions and the generated indexqual conditions.  (These are the same in
   * simple cases, but when special index operators are involved, the former
   * list includes the special conditions while the latter includes the actual
   * indexable conditions derived from them.)  Both lists include partial-index
   * predicates, because we have to recheck predicates as well as index
   * conditions if the bitmap scan becomes lossy.
   *
   * In addition, we return a list of EquivalenceClass pointers for all the
   * top-level indexquals that were possibly-redundantly derived from ECs.
   * This allows removal of scan_clauses that are redundant with such quals.
   * (We do not attempt to detect such redundancies for quals that are within
   * OR subtrees.  This could be done in a less hacky way if we returned the
   * indexquals in RestrictInfo form, but that would be slower and still pretty
   * messy, since we'd have to build new RestrictInfos in many cases.)
   */
  static Plan *
  create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
  					  List **qual, List **indexqual, List **indexECs)
  {
  	Plan	   *plan;
  
  	if (IsA(bitmapqual, BitmapAndPath))
  	{
  		BitmapAndPath *apath = (BitmapAndPath *) bitmapqual;
  		List	   *subplans = NIL;
  		List	   *subquals = NIL;
  		List	   *subindexquals = NIL;
  		List	   *subindexECs = NIL;
  		ListCell   *l;
  
  		/*
  		 * There may well be redundant quals among the subplans, since a
  		 * top-level WHERE qual might have gotten used to form several
  		 * different index quals.  We don't try exceedingly hard to eliminate
  		 * redundancies, but we do eliminate obvious duplicates by using
  		 * list_concat_unique.
  		 */
  		foreach(l, apath->bitmapquals)
  		{
  			Plan	   *subplan;
  			List	   *subqual;
  			List	   *subindexqual;
  			List	   *subindexEC;
  
  			subplan = create_bitmap_subplan(root, (Path *) lfirst(l),
  											&subqual, &subindexqual,
  											&subindexEC);
  			subplans = lappend(subplans, subplan);
  			subquals = list_concat_unique(subquals, subqual);
  			subindexquals = list_concat_unique(subindexquals, subindexqual);
  			/* Duplicates in indexECs aren't worth getting rid of */
  			subindexECs = list_concat(subindexECs, subindexEC);
  		}
  		plan = (Plan *) make_bitmap_and(subplans);
  		plan->startup_cost = apath->path.startup_cost;
  		plan->total_cost = apath->path.total_cost;
  		plan->plan_rows =
  			clamp_row_est(apath->bitmapselectivity * apath->path.parent->tuples);
  		plan->plan_width = 0;	/* meaningless */
  		plan->parallel_aware = false;
  		plan->parallel_safe = apath->path.parallel_safe;
  		*qual = subquals;
  		*indexqual = subindexquals;
  		*indexECs = subindexECs;
  	}
  	else if (IsA(bitmapqual, BitmapOrPath))
  	{
  		BitmapOrPath *opath = (BitmapOrPath *) bitmapqual;
  		List	   *subplans = NIL;
  		List	   *subquals = NIL;
  		List	   *subindexquals = NIL;
  		bool		const_true_subqual = false;
  		bool		const_true_subindexqual = false;
  		ListCell   *l;
  
  		/*
  		 * Here, we only detect qual-free subplans.  A qual-free subplan would
  		 * cause us to generate "... OR true ..."  which we may as well reduce
  		 * to just "true".  We do not try to eliminate redundant subclauses
  		 * because (a) it's not as likely as in the AND case, and (b) we might
  		 * well be working with hundreds or even thousands of OR conditions,
  		 * perhaps from a long IN list.  The performance of list_append_unique
  		 * would be unacceptable.
  		 */
  		foreach(l, opath->bitmapquals)
  		{
  			Plan	   *subplan;
  			List	   *subqual;
  			List	   *subindexqual;
  			List	   *subindexEC;
  
  			subplan = create_bitmap_subplan(root, (Path *) lfirst(l),
  											&subqual, &subindexqual,
  											&subindexEC);
  			subplans = lappend(subplans, subplan);
  			if (subqual == NIL)
  				const_true_subqual = true;
  			else if (!const_true_subqual)
  				subquals = lappend(subquals,
  								   make_ands_explicit(subqual));
  			if (subindexqual == NIL)
  				const_true_subindexqual = true;
  			else if (!const_true_subindexqual)
  				subindexquals = lappend(subindexquals,
  										make_ands_explicit(subindexqual));
  		}
  
  		/*
  		 * In the presence of ScalarArrayOpExpr quals, we might have built
  		 * BitmapOrPaths with just one subpath; don't add an OR step.
  		 */
  		if (list_length(subplans) == 1)
  		{
  			plan = (Plan *) linitial(subplans);
  		}
  		else
  		{
  			plan = (Plan *) make_bitmap_or(subplans);
  			plan->startup_cost = opath->path.startup_cost;
  			plan->total_cost = opath->path.total_cost;
  			plan->plan_rows =
  				clamp_row_est(opath->bitmapselectivity * opath->path.parent->tuples);
  			plan->plan_width = 0;	/* meaningless */
  			plan->parallel_aware = false;
  			plan->parallel_safe = opath->path.parallel_safe;
  		}
  
  		/*
  		 * If there were constant-TRUE subquals, the OR reduces to constant
  		 * TRUE.  Also, avoid generating one-element ORs, which could happen
  		 * due to redundancy elimination or ScalarArrayOpExpr quals.
  		 */
  		if (const_true_subqual)
  			*qual = NIL;
  		else if (list_length(subquals) <= 1)
  			*qual = subquals;
  		else
  			*qual = list_make1(make_orclause(subquals));
  		if (const_true_subindexqual)
  			*indexqual = NIL;
  		else if (list_length(subindexquals) <= 1)
  			*indexqual = subindexquals;
  		else
  			*indexqual = list_make1(make_orclause(subindexquals));
  		*indexECs = NIL;
  	}
  	else if (IsA(bitmapqual, IndexPath))
  	{
  		IndexPath  *ipath = (IndexPath *) bitmapqual;
  		IndexScan  *iscan;
  		List	   *subquals;
  		List	   *subindexquals;
  		List	   *subindexECs;
  		ListCell   *l;
  
  		/* Use the regular indexscan plan build machinery... */
  		iscan = castNode(IndexScan,
  						 create_indexscan_plan(root, ipath,
  											   NIL, NIL, false));
  		/* then convert to a bitmap indexscan */
  		plan = (Plan *) make_bitmap_indexscan(iscan->scan.scanrelid,
  											  iscan->indexid,
  											  iscan->indexqual,
  											  iscan->indexqualorig);
  		/* and set its cost/width fields appropriately */
  		plan->startup_cost = 0.0;
  		plan->total_cost = ipath->indextotalcost;
  		plan->plan_rows =
  			clamp_row_est(ipath->indexselectivity * ipath->path.parent->tuples);
  		plan->plan_width = 0;	/* meaningless */
  		plan->parallel_aware = false;
  		plan->parallel_safe = ipath->path.parallel_safe;
  		/* Extract original index clauses, actual index quals, relevant ECs */
  		subquals = NIL;
  		subindexquals = NIL;
  		subindexECs = NIL;
  		foreach(l, ipath->indexclauses)
  		{
  			IndexClause *iclause = (IndexClause *) lfirst(l);
  			RestrictInfo *rinfo = iclause->rinfo;
  
  			Assert(!rinfo->pseudoconstant);
  			subquals = lappend(subquals, rinfo->clause);
  			subindexquals = list_concat(subindexquals,
  										get_actual_clauses(iclause->indexquals));
  			if (rinfo->parent_ec)
  				subindexECs = lappend(subindexECs, rinfo->parent_ec);
  		}
  		/* We can add any index predicate conditions, too */
  		foreach(l, ipath->indexinfo->indpred)
  		{
  			Expr	   *pred = (Expr *) lfirst(l);
  
  			/*
  			 * We know that the index predicate must have been implied by the
  			 * query condition as a whole, but it may or may not be implied by
  			 * the conditions that got pushed into the bitmapqual.  Avoid
  			 * generating redundant conditions.
  			 */
  			if (!predicate_implied_by(list_make1(pred), subquals, false))
  			{
  				subquals = lappend(subquals, pred);
  				subindexquals = lappend(subindexquals, pred);
  			}
  		}
  		*qual = subquals;
  		*indexqual = subindexquals;
  		*indexECs = subindexECs;
  	}
  	else
  	{
  		elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual));
  		plan = NULL;			/* keep compiler quiet */
  	}
  
  	return plan;
  }
  
  /*
   * create_tidscan_plan
   *	 Returns a tidscan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static TidScan *
  create_tidscan_plan(PlannerInfo *root, TidPath *best_path,
  					List *tlist, List *scan_clauses)
  {
  	TidScan    *scan_plan;
  	Index		scan_relid = best_path->path.parent->relid;
  	List	   *tidquals = best_path->tidquals;
  
  	/* it should be a base rel... */
  	Assert(scan_relid > 0);
  	Assert(best_path->path.parent->rtekind == RTE_RELATION);
  
  	/*
  	 * The qpqual list must contain all restrictions not enforced by the
  	 * tidquals list.  Since tidquals has OR semantics, we have to be careful
  	 * about matching it up to scan_clauses.  It's convenient to handle the
  	 * single-tidqual case separately from the multiple-tidqual case.  In the
  	 * single-tidqual case, we look through the scan_clauses while they are
  	 * still in RestrictInfo form, and drop any that are redundant with the
  	 * tidqual.
  	 *
  	 * In normal cases simple pointer equality checks will be enough to spot
  	 * duplicate RestrictInfos, so we try that first.
  	 *
  	 * Another common case is that a scan_clauses entry is generated from the
  	 * same EquivalenceClass as some tidqual, and is therefore redundant with
  	 * it, though not equal.
  	 *
  	 * Unlike indexpaths, we don't bother with predicate_implied_by(); the
  	 * number of cases where it could win are pretty small.
  	 */
  	if (list_length(tidquals) == 1)
  	{
  		List	   *qpqual = NIL;
  		ListCell   *l;
  
  		foreach(l, scan_clauses)
  		{
  			RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
  
  			if (rinfo->pseudoconstant)
  				continue;		/* we may drop pseudoconstants here */
  			if (list_member_ptr(tidquals, rinfo))
  				continue;		/* simple duplicate */
  			if (is_redundant_derived_clause(rinfo, tidquals))
  				continue;		/* derived from same EquivalenceClass */
  			qpqual = lappend(qpqual, rinfo);
  		}
  		scan_clauses = qpqual;
  	}
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo lists to bare expressions; ignore pseudoconstants */
  	tidquals = extract_actual_clauses(tidquals, false);
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/*
  	 * If we have multiple tidquals, it's more convenient to remove duplicate
  	 * scan_clauses after stripping the RestrictInfos.  In this situation,
  	 * because the tidquals represent OR sub-clauses, they could not have come
  	 * from EquivalenceClasses so we don't have to worry about matching up
  	 * non-identical clauses.  On the other hand, because tidpath.c will have
  	 * extracted those sub-clauses from some OR clause and built its own list,
  	 * we will certainly not have pointer equality to any scan clause.  So
  	 * convert the tidquals list to an explicit OR clause and see if we can
  	 * match it via equal() to any scan clause.
  	 */
  	if (list_length(tidquals) > 1)
  		scan_clauses = list_difference(scan_clauses,
  									   list_make1(make_orclause(tidquals)));
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->path.param_info)
  	{
  		tidquals = (List *)
  			replace_nestloop_params(root, (Node *) tidquals);
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  	}
  
  	scan_plan = make_tidscan(tlist,
  							 scan_clauses,
  							 scan_relid,
  							 tidquals);
  
  	copy_generic_path_info(&scan_plan->scan.plan, &best_path->path);
  
  	return scan_plan;
  }
  
  /*
   * create_subqueryscan_plan
   *	 Returns a subqueryscan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static SubqueryScan *
  create_subqueryscan_plan(PlannerInfo *root, SubqueryScanPath *best_path,
  						 List *tlist, List *scan_clauses)
  {
  	SubqueryScan *scan_plan;
  	RelOptInfo *rel = best_path->path.parent;
  	Index		scan_relid = rel->relid;
  	Plan	   *subplan;
  
  	/* it should be a subquery base rel... */
  	Assert(scan_relid > 0);
  	Assert(rel->rtekind == RTE_SUBQUERY);
  
  	/*
  	 * Recursively create Plan from Path for subquery.  Since we are entering
  	 * a different planner context (subroot), recurse to create_plan not
  	 * create_plan_recurse.
  	 */
  	subplan = create_plan(rel->subroot, best_path->subpath);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->path.param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  		process_subquery_nestloop_params(root,
  										 rel->subplan_params);
  	}
  
  	scan_plan = make_subqueryscan(tlist,
  								  scan_clauses,
  								  scan_relid,
  								  subplan);
  
  	copy_generic_path_info(&scan_plan->scan.plan, &best_path->path);
  
  	return scan_plan;
  }
  
  /*
   * create_functionscan_plan
   *	 Returns a functionscan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static FunctionScan *
  create_functionscan_plan(PlannerInfo *root, Path *best_path,
  						 List *tlist, List *scan_clauses)
  {
  	FunctionScan *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  	List	   *functions;
  
  	/* it should be a function base rel... */
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_FUNCTION);
  	functions = rte->functions;
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  		/* The function expressions could contain nestloop params, too */
  		functions = (List *) replace_nestloop_params(root, (Node *) functions);
  	}
  
  	scan_plan = make_functionscan(tlist, scan_clauses, scan_relid,
  								  functions, rte->funcordinality);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_tablefuncscan_plan
   *	 Returns a tablefuncscan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static TableFuncScan *
  create_tablefuncscan_plan(PlannerInfo *root, Path *best_path,
  						  List *tlist, List *scan_clauses)
  {
  	TableFuncScan *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  	TableFunc  *tablefunc;
  
  	/* it should be a function base rel... */
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_TABLEFUNC);
  	tablefunc = rte->tablefunc;
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  		/* The function expressions could contain nestloop params, too */
  		tablefunc = (TableFunc *) replace_nestloop_params(root, (Node *) tablefunc);
  	}
  
  	scan_plan = make_tablefuncscan(tlist, scan_clauses, scan_relid,
  								   tablefunc);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_valuesscan_plan
   *	 Returns a valuesscan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static ValuesScan *
  create_valuesscan_plan(PlannerInfo *root, Path *best_path,
  					   List *tlist, List *scan_clauses)
  {
  	ValuesScan *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  	List	   *values_lists;
  
  	/* it should be a values base rel... */
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_VALUES);
  	values_lists = rte->values_lists;
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  		/* The values lists could contain nestloop params, too */
  		values_lists = (List *)
  			replace_nestloop_params(root, (Node *) values_lists);
  	}
  
  	scan_plan = make_valuesscan(tlist, scan_clauses, scan_relid,
  								values_lists);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_ctescan_plan
   *	 Returns a ctescan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static CteScan *
  create_ctescan_plan(PlannerInfo *root, Path *best_path,
  					List *tlist, List *scan_clauses)
  {
  	CteScan    *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  	SubPlan    *ctesplan = NULL;
  	int			plan_id;
  	int			cte_param_id;
  	PlannerInfo *cteroot;
  	Index		levelsup;
  	int			ndx;
  	ListCell   *lc;
  
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_CTE);
  	Assert(!rte->self_reference);
  
  	/*
  	 * Find the referenced CTE, and locate the SubPlan previously made for it.
  	 */
  	levelsup = rte->ctelevelsup;
  	cteroot = root;
  	while (levelsup-- > 0)
  	{
  		cteroot = cteroot->parent_root;
  		if (!cteroot)			/* shouldn't happen */
  			elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
  	}
  
  	/*
  	 * Note: cte_plan_ids can be shorter than cteList, if we are still working
  	 * on planning the CTEs (ie, this is a side-reference from another CTE).
  	 * So we mustn't use forboth here.
  	 */
  	ndx = 0;
  	foreach(lc, cteroot->parse->cteList)
  	{
  		CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
  
  		if (strcmp(cte->ctename, rte->ctename) == 0)
  			break;
  		ndx++;
  	}
  	if (lc == NULL)				/* shouldn't happen */
  		elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
  	if (ndx >= list_length(cteroot->cte_plan_ids))
  		elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
  	plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
  	Assert(plan_id > 0);
  	foreach(lc, cteroot->init_plans)
  	{
  		ctesplan = (SubPlan *) lfirst(lc);
  		if (ctesplan->plan_id == plan_id)
  			break;
  	}
  	if (lc == NULL)				/* shouldn't happen */
  		elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
  
  	/*
  	 * We need the CTE param ID, which is the sole member of the SubPlan's
  	 * setParam list.
  	 */
  	cte_param_id = linitial_int(ctesplan->setParam);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  	}
  
  	scan_plan = make_ctescan(tlist, scan_clauses, scan_relid,
  							 plan_id, cte_param_id);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_namedtuplestorescan_plan
   *	 Returns a tuplestorescan plan for the base relation scanned by
   *	'best_path' with restriction clauses 'scan_clauses' and targetlist
   *	'tlist'.
   */
  static NamedTuplestoreScan *
  create_namedtuplestorescan_plan(PlannerInfo *root, Path *best_path,
  								List *tlist, List *scan_clauses)
  {
  	NamedTuplestoreScan *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_NAMEDTUPLESTORE);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  	}
  
  	scan_plan = make_namedtuplestorescan(tlist, scan_clauses, scan_relid,
  										 rte->enrname);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_resultscan_plan
   *	 Returns a Result plan for the RTE_RESULT base relation scanned by
   *	'best_path' with restriction clauses 'scan_clauses' and targetlist
   *	'tlist'.
   */
  static Result *
  create_resultscan_plan(PlannerInfo *root, Path *best_path,
  					   List *tlist, List *scan_clauses)
  {
  	Result	   *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte PG_USED_FOR_ASSERTS_ONLY;
  
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_RESULT);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  	}
  
  	scan_plan = make_result(tlist, (Node *) scan_clauses, NULL);
  
  	copy_generic_path_info(&scan_plan->plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_worktablescan_plan
   *	 Returns a worktablescan plan for the base relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static WorkTableScan *
  create_worktablescan_plan(PlannerInfo *root, Path *best_path,
  						  List *tlist, List *scan_clauses)
  {
  	WorkTableScan *scan_plan;
  	Index		scan_relid = best_path->parent->relid;
  	RangeTblEntry *rte;
  	Index		levelsup;
  	PlannerInfo *cteroot;
  
  	Assert(scan_relid > 0);
  	rte = planner_rt_fetch(scan_relid, root);
  	Assert(rte->rtekind == RTE_CTE);
  	Assert(rte->self_reference);
  
  	/*
  	 * We need to find the worktable param ID, which is in the plan level
  	 * that's processing the recursive UNION, which is one level *below* where
  	 * the CTE comes from.
  	 */
  	levelsup = rte->ctelevelsup;
  	if (levelsup == 0)			/* shouldn't happen */
  		elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
  	levelsup--;
  	cteroot = root;
  	while (levelsup-- > 0)
  	{
  		cteroot = cteroot->parent_root;
  		if (!cteroot)			/* shouldn't happen */
  			elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
  	}
  	if (cteroot->wt_param_id < 0)	/* shouldn't happen */
  		elog(ERROR, "could not find param ID for CTE \"%s\"", rte->ctename);
  
  	/* Sort clauses into best execution order */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
  	scan_clauses = extract_actual_clauses(scan_clauses, false);
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->param_info)
  	{
  		scan_clauses = (List *)
  			replace_nestloop_params(root, (Node *) scan_clauses);
  	}
  
  	scan_plan = make_worktablescan(tlist, scan_clauses, scan_relid,
  								   cteroot->wt_param_id);
  
  	copy_generic_path_info(&scan_plan->scan.plan, best_path);
  
  	return scan_plan;
  }
  
  /*
   * create_foreignscan_plan
   *	 Returns a foreignscan plan for the relation scanned by 'best_path'
   *	 with restriction clauses 'scan_clauses' and targetlist 'tlist'.
   */
  static ForeignScan *
  create_foreignscan_plan(PlannerInfo *root, ForeignPath *best_path,
  						List *tlist, List *scan_clauses)
  {
  	ForeignScan *scan_plan;
  	RelOptInfo *rel = best_path->path.parent;
  	Index		scan_relid = rel->relid;
  	Oid			rel_oid = InvalidOid;
  	Plan	   *outer_plan = NULL;
  
  	Assert(rel->fdwroutine != NULL);
  
  	/* transform the child path if any */
  	if (best_path->fdw_outerpath)
  		outer_plan = create_plan_recurse(root, best_path->fdw_outerpath,
  										 CP_EXACT_TLIST);
  
  	/*
  	 * If we're scanning a base relation, fetch its OID.  (Irrelevant if
  	 * scanning a join relation.)
  	 */
  	if (scan_relid > 0)
  	{
  		RangeTblEntry *rte;
  
  		Assert(rel->rtekind == RTE_RELATION);
  		rte = planner_rt_fetch(scan_relid, root);
  		Assert(rte->rtekind == RTE_RELATION);
  		rel_oid = rte->relid;
  	}
  
  	/*
  	 * Sort clauses into best execution order.  We do this first since the FDW
  	 * might have more info than we do and wish to adjust the ordering.
  	 */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/*
  	 * Let the FDW perform its processing on the restriction clauses and
  	 * generate the plan node.  Note that the FDW might remove restriction
  	 * clauses that it intends to execute remotely, or even add more (if it
  	 * has selected some join clauses for remote use but also wants them
  	 * rechecked locally).
  	 */
  	scan_plan = rel->fdwroutine->GetForeignPlan(root, rel, rel_oid,
  												best_path,
  												tlist, scan_clauses,
  												outer_plan);
  
  	/* Copy cost data from Path to Plan; no need to make FDW do this */
  	copy_generic_path_info(&scan_plan->scan.plan, &best_path->path);
  
  	/* Copy foreign server OID; likewise, no need to make FDW do this */
  	scan_plan->fs_server = rel->serverid;
  
  	/*
  	 * Likewise, copy the relids that are represented by this foreign scan. An
  	 * upper rel doesn't have relids set, but it covers all the base relations
  	 * participating in the underlying scan, so use root's all_baserels.
  	 */
  	if (rel->reloptkind == RELOPT_UPPER_REL)
  		scan_plan->fs_relids = root->all_baserels;
  	else
  		scan_plan->fs_relids = best_path->path.parent->relids;
  
  	/*
  	 * If this is a foreign join, and to make it valid to push down we had to
  	 * assume that the current user is the same as some user explicitly named
  	 * in the query, mark the finished plan as depending on the current user.
  	 */
  	if (rel->useridiscurrent)
  		root->glob->dependsOnRole = true;
  
  	/*
  	 * Replace any outer-relation variables with nestloop params in the qual,
  	 * fdw_exprs and fdw_recheck_quals expressions.  We do this last so that
  	 * the FDW doesn't have to be involved.  (Note that parts of fdw_exprs or
  	 * fdw_recheck_quals could have come from join clauses, so doing this
  	 * beforehand on the scan_clauses wouldn't work.)  We assume
  	 * fdw_scan_tlist contains no such variables.
  	 */
  	if (best_path->path.param_info)
  	{
  		scan_plan->scan.plan.qual = (List *)
  			replace_nestloop_params(root, (Node *) scan_plan->scan.plan.qual);
  		scan_plan->fdw_exprs = (List *)
  			replace_nestloop_params(root, (Node *) scan_plan->fdw_exprs);
  		scan_plan->fdw_recheck_quals = (List *)
  			replace_nestloop_params(root,
  									(Node *) scan_plan->fdw_recheck_quals);
  	}
  
  	/*
  	 * If rel is a base relation, detect whether any system columns are
  	 * requested from the rel.  (If rel is a join relation, rel->relid will be
  	 * 0, but there can be no Var with relid 0 in the rel's targetlist or the
  	 * restriction clauses, so we skip this in that case.  Note that any such
  	 * columns in base relations that were joined are assumed to be contained
  	 * in fdw_scan_tlist.)	This is a bit of a kluge and might go away
  	 * someday, so we intentionally leave it out of the API presented to FDWs.
  	 */
  	scan_plan->fsSystemCol = false;
  	if (scan_relid > 0)
  	{
  		Bitmapset  *attrs_used = NULL;
  		ListCell   *lc;
  		int			i;
  
  		/*
  		 * First, examine all the attributes needed for joins or final output.
  		 * Note: we must look at rel's targetlist, not the attr_needed data,
  		 * because attr_needed isn't computed for inheritance child rels.
  		 */
  		pull_varattnos((Node *) rel->reltarget->exprs, scan_relid, &attrs_used);
  
  		/* Add all the attributes used by restriction clauses. */
  		foreach(lc, rel->baserestrictinfo)
  		{
  			RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
  
  			pull_varattnos((Node *) rinfo->clause, scan_relid, &attrs_used);
  		}
  
  		/* Now, are any system columns requested from rel? */
  		for (i = FirstLowInvalidHeapAttributeNumber + 1; i < 0; i++)
  		{
  			if (bms_is_member(i - FirstLowInvalidHeapAttributeNumber, attrs_used))
  			{
  				scan_plan->fsSystemCol = true;
  				break;
  			}
  		}
  
  		bms_free(attrs_used);
  	}
  
  	return scan_plan;
  }
  
  /*
   * create_customscan_plan
   *
   * Transform a CustomPath into a Plan.
   */
  static CustomScan *
  create_customscan_plan(PlannerInfo *root, CustomPath *best_path,
  					   List *tlist, List *scan_clauses)
  {
  	CustomScan *cplan;
  	RelOptInfo *rel = best_path->path.parent;
  	List	   *custom_plans = NIL;
  	ListCell   *lc;
  
  	/* Recursively transform child paths. */
  	foreach(lc, best_path->custom_paths)
  	{
  		Plan	   *plan = create_plan_recurse(root, (Path *) lfirst(lc),
  											   CP_EXACT_TLIST);
  
  		custom_plans = lappend(custom_plans, plan);
  	}
  
  	/*
  	 * Sort clauses into the best execution order, although custom-scan
  	 * provider can reorder them again.
  	 */
  	scan_clauses = order_qual_clauses(root, scan_clauses);
  
  	/*
  	 * Invoke custom plan provider to create the Plan node represented by the
  	 * CustomPath.
  	 */
  	cplan = castNode(CustomScan,
  					 best_path->methods->PlanCustomPath(root,
  														rel,
  														best_path,
  														tlist,
  														scan_clauses,
  														custom_plans));
  
  	/*
  	 * Copy cost data from Path to Plan; no need to make custom-plan providers
  	 * do this
  	 */
  	copy_generic_path_info(&cplan->scan.plan, &best_path->path);
  
  	/* Likewise, copy the relids that are represented by this custom scan */
  	cplan->custom_relids = best_path->path.parent->relids;
  
  	/*
  	 * Replace any outer-relation variables with nestloop params in the qual
  	 * and custom_exprs expressions.  We do this last so that the custom-plan
  	 * provider doesn't have to be involved.  (Note that parts of custom_exprs
  	 * could have come from join clauses, so doing this beforehand on the
  	 * scan_clauses wouldn't work.)  We assume custom_scan_tlist contains no
  	 * such variables.
  	 */
  	if (best_path->path.param_info)
  	{
  		cplan->scan.plan.qual = (List *)
  			replace_nestloop_params(root, (Node *) cplan->scan.plan.qual);
  		cplan->custom_exprs = (List *)
  			replace_nestloop_params(root, (Node *) cplan->custom_exprs);
  	}
  
  	return cplan;
  }
  
  
  /*****************************************************************************
   *
   *	JOIN METHODS
   *
   *****************************************************************************/
  
  static NestLoop *
  create_nestloop_plan(PlannerInfo *root,
  					 NestPath *best_path)
  {
  	NestLoop   *join_plan;
  	Plan	   *outer_plan;
  	Plan	   *inner_plan;
  	List	   *tlist = build_path_tlist(root, &best_path->path);
  	List	   *joinrestrictclauses = best_path->joinrestrictinfo;
  	List	   *joinclauses;
  	List	   *otherclauses;
  	Relids		outerrelids;
  	List	   *nestParams;
  	Relids		saveOuterRels = root->curOuterRels;
  
  	/* NestLoop can project, so no need to be picky about child tlists */
  	outer_plan = create_plan_recurse(root, best_path->outerjoinpath, 0);
  
  	/* For a nestloop, include outer relids in curOuterRels for inner side */
  	root->curOuterRels = bms_union(root->curOuterRels,
  								   best_path->outerjoinpath->parent->relids);
  
  	inner_plan = create_plan_recurse(root, best_path->innerjoinpath, 0);
  
  	/* Restore curOuterRels */
  	bms_free(root->curOuterRels);
  	root->curOuterRels = saveOuterRels;
  
  	/* Sort join qual clauses into best execution order */
  	joinrestrictclauses = order_qual_clauses(root, joinrestrictclauses);
  
  	/* Get the join qual clauses (in plain expression form) */
  	/* Any pseudoconstant clauses are ignored here */
  	if (IS_OUTER_JOIN(best_path->jointype))
  	{
  		extract_actual_join_clauses(joinrestrictclauses,
  									best_path->path.parent->relids,
  									&joinclauses, &otherclauses);
  	}
  	else
  	{
  		/* We can treat all clauses alike for an inner join */
  		joinclauses = extract_actual_clauses(joinrestrictclauses, false);
  		otherclauses = NIL;
  	}
  
  	/* Replace any outer-relation variables with nestloop params */
  	if (best_path->path.param_info)
  	{
  		joinclauses = (List *)
  			replace_nestloop_params(root, (Node *) joinclauses);
  		otherclauses = (List *)
  			replace_nestloop_params(root, (Node *) otherclauses);
  	}
  
  	/*
  	 * Identify any nestloop parameters that should be supplied by this join
  	 * node, and remove them from root->curOuterParams.
  	 */
  	outerrelids = best_path->outerjoinpath->parent->relids;
  	nestParams = identify_current_nestloop_params(root, outerrelids);
  
  	join_plan = make_nestloop(tlist,
  							  joinclauses,
  							  otherclauses,
  							  nestParams,
  							  outer_plan,
  							  inner_plan,
  							  best_path->jointype,
  							  best_path->inner_unique);
  
  	copy_generic_path_info(&join_plan->join.plan, &best_path->path);
  
  	return join_plan;
  }
  
  static MergeJoin *
  create_mergejoin_plan(PlannerInfo *root,
  					  MergePath *best_path)
  {
  	MergeJoin  *join_plan;
  	Plan	   *outer_plan;
  	Plan	   *inner_plan;
  	List	   *tlist = build_path_tlist(root, &best_path->jpath.path);
  	List	   *joinclauses;
  	List	   *otherclauses;
  	List	   *mergeclauses;
  	List	   *outerpathkeys;
  	List	   *innerpathkeys;
  	int			nClauses;
  	Oid		   *mergefamilies;
  	Oid		   *mergecollations;
  	int		   *mergestrategies;
  	bool	   *mergenullsfirst;
  	PathKey    *opathkey;
  	EquivalenceClass *opeclass;
  	int			i;
  	ListCell   *lc;
  	ListCell   *lop;
  	ListCell   *lip;
  	Path	   *outer_path = best_path->jpath.outerjoinpath;
  	Path	   *inner_path = best_path->jpath.innerjoinpath;
  
  	/*
  	 * MergeJoin can project, so we don't have to demand exact tlists from the
  	 * inputs.  However, if we're intending to sort an input's result, it's
  	 * best to request a small tlist so we aren't sorting more data than
  	 * necessary.
  	 */
  	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
  									 (best_path->outersortkeys != NIL) ? CP_SMALL_TLIST : 0);
  
  	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
  									 (best_path->innersortkeys != NIL) ? CP_SMALL_TLIST : 0);
  
  	/* Sort join qual clauses into best execution order */
  	/* NB: do NOT reorder the mergeclauses */
  	joinclauses = order_qual_clauses(root, best_path->jpath.joinrestrictinfo);
  
  	/* Get the join qual clauses (in plain expression form) */
  	/* Any pseudoconstant clauses are ignored here */
  	if (IS_OUTER_JOIN(best_path->jpath.jointype))
  	{
  		extract_actual_join_clauses(joinclauses,
  									best_path->jpath.path.parent->relids,
  									&joinclauses, &otherclauses);
  	}
  	else
  	{
  		/* We can treat all clauses alike for an inner join */
  		joinclauses = extract_actual_clauses(joinclauses, false);
  		otherclauses = NIL;
  	}
  
  	/*
  	 * Remove the mergeclauses from the list of join qual clauses, leaving the
  	 * list of quals that must be checked as qpquals.
  	 */
  	mergeclauses = get_actual_clauses(best_path->path_mergeclauses);
  	joinclauses = list_difference(joinclauses, mergeclauses);
  
  	/*
  	 * Replace any outer-relation variables with nestloop params.  There
  	 * should not be any in the mergeclauses.
  	 */
  	if (best_path->jpath.path.param_info)
  	{
  		joinclauses = (List *)
  			replace_nestloop_params(root, (Node *) joinclauses);
  		otherclauses = (List *)
  			replace_nestloop_params(root, (Node *) otherclauses);
  	}
  
  	/*
  	 * Rearrange mergeclauses, if needed, so that the outer variable is always
  	 * on the left; mark the mergeclause restrictinfos with correct
  	 * outer_is_left status.
  	 */
  	mergeclauses = get_switched_clauses(best_path->path_mergeclauses,
  										best_path->jpath.outerjoinpath->parent->relids);
  
  	/*
  	 * Create explicit sort nodes for the outer and inner paths if necessary.
  	 */
  	if (best_path->outersortkeys)
  	{
  		Relids		outer_relids = outer_path->parent->relids;
  		Sort	   *sort = make_sort_from_pathkeys(outer_plan,
  												   best_path->outersortkeys,
  												   outer_relids);
  
  		label_sort_with_costsize(root, sort, -1.0);
  		outer_plan = (Plan *) sort;
  		outerpathkeys = best_path->outersortkeys;
  	}
  	else
  		outerpathkeys = best_path->jpath.outerjoinpath->pathkeys;
  
  	if (best_path->innersortkeys)
  	{
  		Relids		inner_relids = inner_path->parent->relids;
  		Sort	   *sort = make_sort_from_pathkeys(inner_plan,
  												   best_path->innersortkeys,
  												   inner_relids);
  
  		label_sort_with_costsize(root, sort, -1.0);
  		inner_plan = (Plan *) sort;
  		innerpathkeys = best_path->innersortkeys;
  	}
  	else
  		innerpathkeys = best_path->jpath.innerjoinpath->pathkeys;
  
  	/*
  	 * If specified, add a materialize node to shield the inner plan from the
  	 * need to handle mark/restore.
  	 */
  	if (best_path->materialize_inner)
  	{
  		Plan	   *matplan = (Plan *) make_material(inner_plan);
  
  		/*
  		 * We assume the materialize will not spill to disk, and therefore
  		 * charge just cpu_operator_cost per tuple.  (Keep this estimate in
  		 * sync with final_cost_mergejoin.)
  		 */
  		copy_plan_costsize(matplan, inner_plan);
  		matplan->total_cost += cpu_operator_cost * matplan->plan_rows;
  
  		inner_plan = matplan;
  	}
  
  	/*
  	 * Compute the opfamily/collation/strategy/nullsfirst arrays needed by the
  	 * executor.  The information is in the pathkeys for the two inputs, but
  	 * we need to be careful about the possibility of mergeclauses sharing a
  	 * pathkey, as well as the possibility that the inner pathkeys are not in
  	 * an order matching the mergeclauses.
  	 */
  	nClauses = list_length(mergeclauses);
  	Assert(nClauses == list_length(best_path->path_mergeclauses));
  	mergefamilies = (Oid *) palloc(nClauses * sizeof(Oid));
  	mergecollations = (Oid *) palloc(nClauses * sizeof(Oid));
  	mergestrategies = (int *) palloc(nClauses * sizeof(int));
  	mergenullsfirst = (bool *) palloc(nClauses * sizeof(bool));
  
  	opathkey = NULL;
  	opeclass = NULL;
  	lop = list_head(outerpathkeys);
  	lip = list_head(innerpathkeys);
  	i = 0;
  	foreach(lc, best_path->path_mergeclauses)
  	{
  		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
  		EquivalenceClass *oeclass;
  		EquivalenceClass *ieclass;
  		PathKey    *ipathkey = NULL;
  		EquivalenceClass *ipeclass = NULL;
  		bool		first_inner_match = false;
  
  		/* fetch outer/inner eclass from mergeclause */
  		if (rinfo->outer_is_left)
  		{
  			oeclass = rinfo->left_ec;
  			ieclass = rinfo->right_ec;
  		}
  		else
  		{
  			oeclass = rinfo->right_ec;
  			ieclass = rinfo->left_ec;
  		}
  		Assert(oeclass != NULL);
  		Assert(ieclass != NULL);
  
  		/*
  		 * We must identify the pathkey elements associated with this clause
  		 * by matching the eclasses (which should give a unique match, since
  		 * the pathkey lists should be canonical).  In typical cases the merge
  		 * clauses are one-to-one with the pathkeys, but when dealing with
  		 * partially redundant query conditions, things are more complicated.
  		 *
  		 * lop and lip reference the first as-yet-unmatched pathkey elements.
  		 * If they're NULL then all pathkey elements have been matched.
  		 *
  		 * The ordering of the outer pathkeys should match the mergeclauses,
  		 * by construction (see find_mergeclauses_for_outer_pathkeys()). There
  		 * could be more than one mergeclause for the same outer pathkey, but
  		 * no pathkey may be entirely skipped over.
  		 */
  		if (oeclass != opeclass)	/* multiple matches are not interesting */
  		{
  			/* doesn't match the current opathkey, so must match the next */
  			if (lop == NULL)
  				elog(ERROR, "outer pathkeys do not match mergeclauses");
  			opathkey = (PathKey *) lfirst(lop);
  			opeclass = opathkey->pk_eclass;
  			lop = lnext(lop);
  			if (oeclass != opeclass)
  				elog(ERROR, "outer pathkeys do not match mergeclauses");
  		}
  
  		/*
  		 * The inner pathkeys likewise should not have skipped-over keys, but
  		 * it's possible for a mergeclause to reference some earlier inner
  		 * pathkey if we had redundant pathkeys.  For example we might have
  		 * mergeclauses like "o.a = i.x AND o.b = i.y AND o.c = i.x".  The
  		 * implied inner ordering is then "ORDER BY x, y, x", but the pathkey
  		 * mechanism drops the second sort by x as redundant, and this code
  		 * must cope.
  		 *
  		 * It's also possible for the implied inner-rel ordering to be like
  		 * "ORDER BY x, y, x DESC".  We still drop the second instance of x as
  		 * redundant; but this means that the sort ordering of a redundant
  		 * inner pathkey should not be considered significant.  So we must
  		 * detect whether this is the first clause matching an inner pathkey.
  		 */
  		if (lip)
  		{
  			ipathkey = (PathKey *) lfirst(lip);
  			ipeclass = ipathkey->pk_eclass;
  			if (ieclass == ipeclass)
  			{
  				/* successful first match to this inner pathkey */
  				lip = lnext(lip);
  				first_inner_match = true;
  			}
  		}
  		if (!first_inner_match)
  		{
  			/* redundant clause ... must match something before lip */
  			ListCell   *l2;
  
  			foreach(l2, innerpathkeys)
  			{
  				if (l2 == lip)
  					break;
  				ipathkey = (PathKey *) lfirst(l2);
  				ipeclass = ipathkey->pk_eclass;
  				if (ieclass == ipeclass)
  					break;
  			}
  			if (ieclass != ipeclass)
  				elog(ERROR, "inner pathkeys do not match mergeclauses");
  		}
  
  		/*
  		 * The pathkeys should always match each other as to opfamily and
  		 * collation (which affect equality), but if we're considering a
  		 * redundant inner pathkey, its sort ordering might not match.  In
  		 * such cases we may ignore the inner pathkey's sort ordering and use
  		 * the outer's.  (In effect, we're lying to the executor about the
  		 * sort direction of this inner column, but it does not matter since
  		 * the run-time row comparisons would only reach this column when
  		 * there's equality for the earlier column containing the same eclass.
  		 * There could be only one value in this column for the range of inner
  		 * rows having a given value in the earlier column, so it does not
  		 * matter which way we imagine this column to be ordered.)  But a
  		 * non-redundant inner pathkey had better match outer's ordering too.
  		 */
  		if (opathkey->pk_opfamily != ipathkey->pk_opfamily ||
  			opathkey->pk_eclass->ec_collation != ipathkey->pk_eclass->ec_collation)
  			elog(ERROR, "left and right pathkeys do not match in mergejoin");
  		if (first_inner_match &&
  			(opathkey->pk_strategy != ipathkey->pk_strategy ||
  			 opathkey->pk_nulls_first != ipathkey->pk_nulls_first))
  			elog(ERROR, "left and right pathkeys do not match in mergejoin");
  
  		/* OK, save info for executor */
  		mergefamilies[i] = opathkey->pk_opfamily;
  		mergecollations[i] = opathkey->pk_eclass->ec_collation;
  		mergestrategies[i] = opathkey->pk_strategy;
  		mergenullsfirst[i] = opathkey->pk_nulls_first;
  		i++;
  	}
  
  	/*
  	 * Note: it is not an error if we have additional pathkey elements (i.e.,
  	 * lop or lip isn't NULL here).  The input paths might be better-sorted
  	 * than we need for the current mergejoin.
  	 */
  
  	/*
  	 * Now we can build the mergejoin node.
  	 */
  	join_plan = make_mergejoin(tlist,
  							   joinclauses,
  							   otherclauses,
  							   mergeclauses,
  							   mergefamilies,
  							   mergecollations,
  							   mergestrategies,
  							   mergenullsfirst,
  							   outer_plan,
  							   inner_plan,
  							   best_path->jpath.jointype,
  							   best_path->jpath.inner_unique,
  							   best_path->skip_mark_restore);
  
  	/* Costs of sort and material steps are included in path cost already */
  	copy_generic_path_info(&join_plan->join.plan, &best_path->jpath.path);
  
  	return join_plan;
  }
  
  static HashJoin *
  create_hashjoin_plan(PlannerInfo *root,
  					 HashPath *best_path)
  {
  	HashJoin   *join_plan;
  	Hash	   *hash_plan;
  	Plan	   *outer_plan;
  	Plan	   *inner_plan;
  	List	   *tlist = build_path_tlist(root, &best_path->jpath.path);
  	List	   *joinclauses;
  	List	   *otherclauses;
  	List	   *hashclauses;
  	List	   *hashoperators = NIL;
  	List	   *hashcollations = NIL;
  	List	   *inner_hashkeys = NIL;
  	List	   *outer_hashkeys = NIL;
  	Oid			skewTable = InvalidOid;
  	AttrNumber	skewColumn = InvalidAttrNumber;
  	bool		skewInherit = false;
  	ListCell   *lc;
  
  	/*
  	 * HashJoin can project, so we don't have to demand exact tlists from the
  	 * inputs.  However, it's best to request a small tlist from the inner
  	 * side, so that we aren't storing more data than necessary.  Likewise, if
  	 * we anticipate batching, request a small tlist from the outer side so
  	 * that we don't put extra data in the outer batch files.
  	 */
  	outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath,
  									 (best_path->num_batches > 1) ? CP_SMALL_TLIST : 0);
  
  	inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath,
  									 CP_SMALL_TLIST);
  
  	/* Sort join qual clauses into best execution order */
  	joinclauses = order_qual_clauses(root, best_path->jpath.joinrestrictinfo);
  	/* There's no point in sorting the hash clauses ... */
  
  	/* Get the join qual clauses (in plain expression form) */
  	/* Any pseudoconstant clauses are ignored here */
  	if (IS_OUTER_JOIN(best_path->jpath.jointype))
  	{
  		extract_actual_join_clauses(joinclauses,
  									best_path->jpath.path.parent->relids,
  									&joinclauses, &otherclauses);
  	}
  	else
  	{
  		/* We can treat all clauses alike for an inner join */
  		joinclauses = extract_actual_clauses(joinclauses, false);
  		otherclauses = NIL;
  	}
  
  	/*
  	 * Remove the hashclauses from the list of join qual clauses, leaving the
  	 * list of quals that must be checked as qpquals.
  	 */
  	hashclauses = get_actual_clauses(best_path->path_hashclauses);
  	joinclauses = list_difference(joinclauses, hashclauses);
  
  	/*
  	 * Replace any outer-relation variables with nestloop params.  There
  	 * should not be any in the hashclauses.
  	 */
  	if (best_path->jpath.path.param_info)
  	{
  		joinclauses = (List *)
  			replace_nestloop_params(root, (Node *) joinclauses);
  		otherclauses = (List *)
  			replace_nestloop_params(root, (Node *) otherclauses);
  	}
  
  	/*
  	 * Rearrange hashclauses, if needed, so that the outer variable is always
  	 * on the left.
  	 */
  	hashclauses = get_switched_clauses(best_path->path_hashclauses,
  									   best_path->jpath.outerjoinpath->parent->relids);
  
  	/*
  	 * If there is a single join clause and we can identify the outer variable
  	 * as a simple column reference, supply its identity for possible use in
  	 * skew optimization.  (Note: in principle we could do skew optimization
  	 * with multiple join clauses, but we'd have to be able to determine the
  	 * most common combinations of outer values, which we don't currently have
  	 * enough stats for.)
  	 */
  	if (list_length(hashclauses) == 1)
  	{
  		OpExpr	   *clause = (OpExpr *) linitial(hashclauses);
  		Node	   *node;
  
  		Assert(is_opclause(clause));
  		node = (Node *) linitial(clause->args);
  		if (IsA(node, RelabelType))
  			node = (Node *) ((RelabelType *) node)->arg;
  		if (IsA(node, Var))
  		{
  			Var		   *var = (Var *) node;
  			RangeTblEntry *rte;
  
  			rte = root->simple_rte_array[var->varno];
  			if (rte->rtekind == RTE_RELATION)
  			{
  				skewTable = rte->relid;
  				skewColumn = var->varattno;
  				skewInherit = rte->inh;
  			}
  		}
  	}
  
  	/*
  	 * Collect hash related information. The hashed expressions are
  	 * deconstructed into outer/inner expressions, so they can be computed
  	 * separately (inner expressions are used to build the hashtable via Hash,
  	 * outer expressions to perform lookups of tuples from HashJoin's outer
  	 * plan in the hashtable). Also collect operator information necessary to
  	 * build the hashtable.
  	 */
  	foreach(lc, hashclauses)
  	{
  		OpExpr	   *hclause = lfirst_node(OpExpr, lc);
  
  		hashoperators = lappend_oid(hashoperators, hclause->opno);
  		hashcollations = lappend_oid(hashcollations, hclause->inputcollid);
  		outer_hashkeys = lappend(outer_hashkeys, linitial(hclause->args));
  		inner_hashkeys = lappend(inner_hashkeys, lsecond(hclause->args));
  	}
  
  	/*
  	 * Build the hash node and hash join node.
  	 */
  	hash_plan = make_hash(inner_plan,
  						  inner_hashkeys,
  						  skewTable,
  						  skewColumn,
  						  skewInherit);
  
  	/*
  	 * Set Hash node's startup & total costs equal to total cost of input
  	 * plan; this only affects EXPLAIN display not decisions.
  	 */
  	copy_plan_costsize(&hash_plan->plan, inner_plan);
  	hash_plan->plan.startup_cost = hash_plan->plan.total_cost;
  
  	/*
  	 * If parallel-aware, the executor will also need an estimate of the total
  	 * number of rows expected from all participants so that it can size the
  	 * shared hash table.
  	 */
  	if (best_path->jpath.path.parallel_aware)
  	{
  		hash_plan->plan.parallel_aware = true;
  		hash_plan->rows_total = best_path->inner_rows_total;
  	}
  
  	join_plan = make_hashjoin(tlist,
  							  joinclauses,
  							  otherclauses,
  							  hashclauses,
  							  hashoperators,
  							  hashcollations,
  							  outer_hashkeys,
  							  outer_plan,
  							  (Plan *) hash_plan,
  							  best_path->jpath.jointype,
  							  best_path->jpath.inner_unique);
  
  	copy_generic_path_info(&join_plan->join.plan, &best_path->jpath.path);
  
  	return join_plan;
  }
  
  
  /*****************************************************************************
   *
   *	SUPPORTING ROUTINES
   *
   *****************************************************************************/
  
  /*
   * replace_nestloop_params
   *	  Replace outer-relation Vars and PlaceHolderVars in the given expression
   *	  with nestloop Params
   *
   * All Vars and PlaceHolderVars belonging to the relation(s) identified by
   * root->curOuterRels are replaced by Params, and entries are added to
   * root->curOuterParams if not already present.
   */
  static Node *
  replace_nestloop_params(PlannerInfo *root, Node *expr)
  {
  	/* No setup needed for tree walk, so away we go */
  	return replace_nestloop_params_mutator(expr, root);
  }
  
  static Node *
  replace_nestloop_params_mutator(Node *node, PlannerInfo *root)
  {
  	if (node == NULL)
  		return NULL;
  	if (IsA(node, Var))
  	{
  		Var		   *var = (Var *) node;
  
  		/* Upper-level Vars should be long gone at this point */
  		Assert(var->varlevelsup == 0);
  		/* If not to be replaced, we can just return the Var unmodified */
  		if (!bms_is_member(var->varno, root->curOuterRels))
  			return node;
  		/* Replace the Var with a nestloop Param */
  		return (Node *) replace_nestloop_param_var(root, var);
  	}
  	if (IsA(node, PlaceHolderVar))
  	{
  		PlaceHolderVar *phv = (PlaceHolderVar *) node;
  
  		/* Upper-level PlaceHolderVars should be long gone at this point */
  		Assert(phv->phlevelsup == 0);
  
  		/*
  		 * Check whether we need to replace the PHV.  We use bms_overlap as a
  		 * cheap/quick test to see if the PHV might be evaluated in the outer
  		 * rels, and then grab its PlaceHolderInfo to tell for sure.
  		 */
  		if (!bms_overlap(phv->phrels, root->curOuterRels) ||
  			!bms_is_subset(find_placeholder_info(root, phv, false)->ph_eval_at,
  						   root->curOuterRels))
  		{
  			/*
  			 * We can't replace the whole PHV, but we might still need to
  			 * replace Vars or PHVs within its expression, in case it ends up
  			 * actually getting evaluated here.  (It might get evaluated in
  			 * this plan node, or some child node; in the latter case we don't
  			 * really need to process the expression here, but we haven't got
  			 * enough info to tell if that's the case.)  Flat-copy the PHV
  			 * node and then recurse on its expression.
  			 *
  			 * Note that after doing this, we might have different
  			 * representations of the contents of the same PHV in different
  			 * parts of the plan tree.  This is OK because equal() will just
  			 * match on phid/phlevelsup, so setrefs.c will still recognize an
  			 * upper-level reference to a lower-level copy of the same PHV.
  			 */
  			PlaceHolderVar *newphv = makeNode(PlaceHolderVar);
  
  			memcpy(newphv, phv, sizeof(PlaceHolderVar));
  			newphv->phexpr = (Expr *)
  				replace_nestloop_params_mutator((Node *) phv->phexpr,
  												root);
  			return (Node *) newphv;
  		}
  		/* Replace the PlaceHolderVar with a nestloop Param */
  		return (Node *) replace_nestloop_param_placeholdervar(root, phv);
  	}
  	return expression_tree_mutator(node,
  								   replace_nestloop_params_mutator,
  								   (void *) root);
  }
  
  /*
   * fix_indexqual_references
   *	  Adjust indexqual clauses to the form the executor's indexqual
   *	  machinery needs.
   *
   * We have three tasks here:
   *	* Select the actual qual clauses out of the input IndexClause list,
   *	  and remove RestrictInfo nodes from the qual clauses.
   *	* Replace any outer-relation Var or PHV nodes with nestloop Params.
   *	  (XXX eventually, that responsibility should go elsewhere?)
   *	* Index keys must be represented by Var nodes with varattno set to the
   *	  index's attribute number, not the attribute number in the original rel.
   *
   * *stripped_indexquals_p receives a list of the actual qual clauses.
   *
   * *fixed_indexquals_p receives a list of the adjusted quals.  This is a copy
   * that shares no substructure with the original; this is needed in case there
   * are subplans in it (we need two separate copies of the subplan tree, or
   * things will go awry).
   */
  static void
  fix_indexqual_references(PlannerInfo *root, IndexPath *index_path,
  						 List **stripped_indexquals_p, List **fixed_indexquals_p)
  {
  	IndexOptInfo *index = index_path->indexinfo;
  	List	   *stripped_indexquals;
  	List	   *fixed_indexquals;
  	ListCell   *lc;
  
  	stripped_indexquals = fixed_indexquals = NIL;
  
  	foreach(lc, index_path->indexclauses)
  	{
  		IndexClause *iclause = lfirst_node(IndexClause, lc);
  		int			indexcol = iclause->indexcol;
  		ListCell   *lc2;
  
  		foreach(lc2, iclause->indexquals)
  		{
  			RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
  			Node	   *clause = (Node *) rinfo->clause;
  
  			stripped_indexquals = lappend(stripped_indexquals, clause);
  			clause = fix_indexqual_clause(root, index, indexcol,
  										  clause, iclause->indexcols);
  			fixed_indexquals = lappend(fixed_indexquals, clause);
  		}
  	}
  
  	*stripped_indexquals_p = stripped_indexquals;
  	*fixed_indexquals_p = fixed_indexquals;
  }
  
  /*
   * fix_indexorderby_references
   *	  Adjust indexorderby clauses to the form the executor's index
   *	  machinery needs.
   *
   * This is a simplified version of fix_indexqual_references.  The input is
   * bare clauses and a separate indexcol list, instead of IndexClauses.
   */
  static List *
  fix_indexorderby_references(PlannerInfo *root, IndexPath *index_path)
  {
  	IndexOptInfo *index = index_path->indexinfo;
  	List	   *fixed_indexorderbys;
  	ListCell   *lcc,
  			   *lci;
  
  	fixed_indexorderbys = NIL;
  
  	forboth(lcc, index_path->indexorderbys, lci, index_path->indexorderbycols)
  	{
  		Node	   *clause = (Node *) lfirst(lcc);
  		int			indexcol = lfirst_int(lci);
  
  		clause = fix_indexqual_clause(root, index, indexcol, clause, NIL);
  		fixed_indexorderbys = lappend(fixed_indexorderbys, clause);
  	}
  
  	return fixed_indexorderbys;
  }
  
  /*
   * fix_indexqual_clause
   *	  Convert a single indexqual clause to the form needed by the executor.
   *
   * We replace nestloop params here, and replace the index key variables
   * or expressions by index Var nodes.
   */
  static Node *
  fix_indexqual_clause(PlannerInfo *root, IndexOptInfo *index, int indexcol,
  					 Node *clause, List *indexcolnos)
  {
  	/*
  	 * Replace any outer-relation variables with nestloop params.
  	 *
  	 * This also makes a copy of the clause, so it's safe to modify it
  	 * in-place below.
  	 */
  	clause = replace_nestloop_params(root, clause);
  
  	if (IsA(clause, OpExpr))
  	{
  		OpExpr	   *op = (OpExpr *) clause;
  
  		/* Replace the indexkey expression with an index Var. */
  		linitial(op->args) = fix_indexqual_operand(linitial(op->args),
  												   index,
  												   indexcol);
  	}
  	else if (IsA(clause, RowCompareExpr))
  	{
  		RowCompareExpr *rc = (RowCompareExpr *) clause;
  		ListCell   *lca,
  				   *lcai;
  
  		/* Replace the indexkey expressions with index Vars. */
  		Assert(list_length(rc->largs) == list_length(indexcolnos));
  		forboth(lca, rc->largs, lcai, indexcolnos)
  		{
  			lfirst(lca) = fix_indexqual_operand(lfirst(lca),
  												index,
  												lfirst_int(lcai));
  		}
  	}
  	else if (IsA(clause, ScalarArrayOpExpr))
  	{
  		ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause;
  
  		/* Replace the indexkey expression with an index Var. */
  		linitial(saop->args) = fix_indexqual_operand(linitial(saop->args),
  													 index,
  													 indexcol);
  	}
  	else if (IsA(clause, NullTest))
  	{
  		NullTest   *nt = (NullTest *) clause;
  
  		/* Replace the indexkey expression with an index Var. */
  		nt->arg = (Expr *) fix_indexqual_operand((Node *) nt->arg,
  												 index,
  												 indexcol);
  	}
  	else
  		elog(ERROR, "unsupported indexqual type: %d",
  			 (int) nodeTag(clause));
  
  	return clause;
  }
  
  /*
   * fix_indexqual_operand
   *	  Convert an indexqual expression to a Var referencing the index column.
   *
   * We represent index keys by Var nodes having varno == INDEX_VAR and varattno
   * equal to the index's attribute number (index column position).
   *
   * Most of the code here is just for sanity cross-checking that the given
   * expression actually matches the index column it's claimed to.
   */
  static Node *
  fix_indexqual_operand(Node *node, IndexOptInfo *index, int indexcol)
  {
  	Var		   *result;
  	int			pos;
  	ListCell   *indexpr_item;
  
  	/*
  	 * Remove any binary-compatible relabeling of the indexkey
  	 */
  	if (IsA(node, RelabelType))
  		node = (Node *) ((RelabelType *) node)->arg;
  
  	Assert(indexcol >= 0 && indexcol < index->ncolumns);
  
  	if (index->indexkeys[indexcol] != 0)
  	{
  		/* It's a simple index column */
  		if (IsA(node, Var) &&
  			((Var *) node)->varno == index->rel->relid &&
  			((Var *) node)->varattno == index->indexkeys[indexcol])
  		{
  			result = (Var *) copyObject(node);
  			result->varno = INDEX_VAR;
  			result->varattno = indexcol + 1;
  			return (Node *) result;
  		}
  		else
  			elog(ERROR, "index key does not match expected index column");
  	}
  
  	/* It's an index expression, so find and cross-check the expression */
  	indexpr_item = list_head(index->indexprs);
  	for (pos = 0; pos < index->ncolumns; pos++)
  	{
  		if (index->indexkeys[pos] == 0)
  		{
  			if (indexpr_item == NULL)
  				elog(ERROR, "too few entries in indexprs list");
  			if (pos == indexcol)
  			{
  				Node	   *indexkey;
  
  				indexkey = (Node *) lfirst(indexpr_item);
  				if (indexkey && IsA(indexkey, RelabelType))
  					indexkey = (Node *) ((RelabelType *) indexkey)->arg;
  				if (equal(node, indexkey))
  				{
  					result = makeVar(INDEX_VAR, indexcol + 1,
  									 exprType(lfirst(indexpr_item)), -1,
  									 exprCollation(lfirst(indexpr_item)),
  									 0);
  					return (Node *) result;
  				}
  				else
  					elog(ERROR, "index key does not match expected index column");
  			}
  			indexpr_item = lnext(indexpr_item);
  		}
  	}
  
  	/* Oops... */
  	elog(ERROR, "index key does not match expected index column");
  	return NULL;				/* keep compiler quiet */
  }
  
  /*
   * get_switched_clauses
   *	  Given a list of merge or hash joinclauses (as RestrictInfo nodes),
   *	  extract the bare clauses, and rearrange the elements within the
   *	  clauses, if needed, so the outer join variable is on the left and
   *	  the inner is on the right.  The original clause data structure is not
   *	  touched; a modified list is returned.  We do, however, set the transient
   *	  outer_is_left field in each RestrictInfo to show which side was which.
   */
  static List *
  get_switched_clauses(List *clauses, Relids outerrelids)
  {
  	List	   *t_list = NIL;
  	ListCell   *l;
  
  	foreach(l, clauses)
  	{
  		RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
  		OpExpr	   *clause = (OpExpr *) restrictinfo->clause;
  
  		Assert(is_opclause(clause));
  		if (bms_is_subset(restrictinfo->right_relids, outerrelids))
  		{
  			/*
  			 * Duplicate just enough of the structure to allow commuting the
  			 * clause without changing the original list.  Could use
  			 * copyObject, but a complete deep copy is overkill.
  			 */
  			OpExpr	   *temp = makeNode(OpExpr);
  
  			temp->opno = clause->opno;
  			temp->opfuncid = InvalidOid;
  			temp->opresulttype = clause->opresulttype;
  			temp->opretset = clause->opretset;
  			temp->opcollid = clause->opcollid;
  			temp->inputcollid = clause->inputcollid;
  			temp->args = list_copy(clause->args);
  			temp->location = clause->location;
  			/* Commute it --- note this modifies the temp node in-place. */
  			CommuteOpExpr(temp);
  			t_list = lappend(t_list, temp);
  			restrictinfo->outer_is_left = false;
  		}
  		else
  		{
  			Assert(bms_is_subset(restrictinfo->left_relids, outerrelids));
  			t_list = lappend(t_list, clause);
  			restrictinfo->outer_is_left = true;
  		}
  	}
  	return t_list;
  }
  
  /*
   * order_qual_clauses
   *		Given a list of qual clauses that will all be evaluated at the same
   *		plan node, sort the list into the order we want to check the quals
   *		in at runtime.
   *
   * When security barrier quals are used in the query, we may have quals with
   * different security levels in the list.  Quals of lower security_level
   * must go before quals of higher security_level, except that we can grant
   * exceptions to move up quals that are leakproof.  When security level
   * doesn't force the decision, we prefer to order clauses by estimated
   * execution cost, cheapest first.
   *
   * Ideally the order should be driven by a combination of execution cost and
   * selectivity, but it's not immediately clear how to account for both,
   * and given the uncertainty of the estimates the reliability of the decisions
   * would be doubtful anyway.  So we just order by security level then
   * estimated per-tuple cost, being careful not to change the order when
   * (as is often the case) the estimates are identical.
   *
   * Although this will work on either bare clauses or RestrictInfos, it's
   * much faster to apply it to RestrictInfos, since it can re-use cost
   * information that is cached in RestrictInfos.  XXX in the bare-clause
   * case, we are also not able to apply security considerations.  That is
   * all right for the moment, because the bare-clause case doesn't occur
   * anywhere that barrier quals could be present, but it would be better to
   * get rid of it.
   *
   * Note: some callers pass lists that contain entries that will later be
   * removed; this is the easiest way to let this routine see RestrictInfos
   * instead of bare clauses.  This is another reason why trying to consider
   * selectivity in the ordering would likely do the wrong thing.
   */
  static List *
  order_qual_clauses(PlannerInfo *root, List *clauses)
  {
  	typedef struct
  	{
  		Node	   *clause;
  		Cost		cost;
  		Index		security_level;
  	} QualItem;
  	int			nitems = list_length(clauses);
  	QualItem   *items;
  	ListCell   *lc;
  	int			i;
  	List	   *result;
  
  	/* No need to work hard for 0 or 1 clause */
  	if (nitems <= 1)
  		return clauses;
  
  	/*
  	 * Collect the items and costs into an array.  This is to avoid repeated
  	 * cost_qual_eval work if the inputs aren't RestrictInfos.
  	 */
  	items = (QualItem *) palloc(nitems * sizeof(QualItem));
  	i = 0;
  	foreach(lc, clauses)
  	{
  		Node	   *clause = (Node *) lfirst(lc);
  		QualCost	qcost;
  
  		cost_qual_eval_node(&qcost, clause, root);
  		items[i].clause = clause;
  		items[i].cost = qcost.per_tuple;
  		if (IsA(clause, RestrictInfo))
  		{
  			RestrictInfo *rinfo = (RestrictInfo *) clause;
  
  			/*
  			 * If a clause is leakproof, it doesn't have to be constrained by
  			 * its nominal security level.  If it's also reasonably cheap
  			 * (here defined as 10X cpu_operator_cost), pretend it has
  			 * security_level 0, which will allow it to go in front of
  			 * more-expensive quals of lower security levels.  Of course, that
  			 * will also force it to go in front of cheaper quals of its own
  			 * security level, which is not so great, but we can alleviate
  			 * that risk by applying the cost limit cutoff.
  			 */
  			if (rinfo->leakproof && items[i].cost < 10 * cpu_operator_cost)
  				items[i].security_level = 0;
  			else
  				items[i].security_level = rinfo->security_level;
  		}
  		else
  			items[i].security_level = 0;
  		i++;
  	}
  
  	/*
  	 * Sort.  We don't use qsort() because it's not guaranteed stable for
  	 * equal keys.  The expected number of entries is small enough that a
  	 * simple insertion sort should be good enough.
  	 */
  	for (i = 1; i < nitems; i++)
  	{
  		QualItem	newitem = items[i];
  		int			j;
  
  		/* insert newitem into the already-sorted subarray */
  		for (j = i; j > 0; j--)
  		{
  			QualItem   *olditem = &items[j - 1];
  
  			if (newitem.security_level > olditem->security_level ||
  				(newitem.security_level == olditem->security_level &&
  				 newitem.cost >= olditem->cost))
  				break;
  			items[j] = *olditem;
  		}
  		items[j] = newitem;
  	}
  
  	/* Convert back to a list */
  	result = NIL;
  	for (i = 0; i < nitems; i++)
  		result = lappend(result, items[i].clause);
  
  	return result;
  }
  
  /*
   * Copy cost and size info from a Path node to the Plan node created from it.
   * The executor usually won't use this info, but it's needed by EXPLAIN.
   * Also copy the parallel-related flags, which the executor *will* use.
   */
  static void
  copy_generic_path_info(Plan *dest, Path *src)
  {
  	dest->startup_cost = src->startup_cost;
  	dest->total_cost = src->total_cost;
  	dest->plan_rows = src->rows;
  	dest->plan_width = src->pathtarget->width;
  	dest->parallel_aware = src->parallel_aware;
  	dest->parallel_safe = src->parallel_safe;
  }
  
  /*
   * Copy cost and size info from a lower plan node to an inserted node.
   * (Most callers alter the info after copying it.)
   */
  static void
  copy_plan_costsize(Plan *dest, Plan *src)
  {
  	dest->startup_cost = src->startup_cost;
  	dest->total_cost = src->total_cost;
  	dest->plan_rows = src->plan_rows;
  	dest->plan_width = src->plan_width;
  	/* Assume the inserted node is not parallel-aware. */
  	dest->parallel_aware = false;
  	/* Assume the inserted node is parallel-safe, if child plan is. */
  	dest->parallel_safe = src->parallel_safe;
  }
  
  /*
   * Some places in this file build Sort nodes that don't have a directly
   * corresponding Path node.  The cost of the sort is, or should have been,
   * included in the cost of the Path node we're working from, but since it's
   * not split out, we have to re-figure it using cost_sort().  This is just
   * to label the Sort node nicely for EXPLAIN.
   *
   * limit_tuples is as for cost_sort (in particular, pass -1 if no limit)
   */
  static void
  label_sort_with_costsize(PlannerInfo *root, Sort *plan, double limit_tuples)
  {
  	Plan	   *lefttree = plan->plan.lefttree;
  	Path		sort_path;		/* dummy for result of cost_sort */
  
  	cost_sort(&sort_path, root, NIL,
  			  lefttree->total_cost,
  			  lefttree->plan_rows,
  			  lefttree->plan_width,
  			  0.0,
  			  work_mem,
  			  limit_tuples);
  	plan->plan.startup_cost = sort_path.startup_cost;
  	plan->plan.total_cost = sort_path.total_cost;
  	plan->plan.plan_rows = lefttree->plan_rows;
  	plan->plan.plan_width = lefttree->plan_width;
  	plan->plan.parallel_aware = false;
  	plan->plan.parallel_safe = lefttree->parallel_safe;
  }
  
  /*
   * bitmap_subplan_mark_shared
   *	 Set isshared flag in bitmap subplan so that it will be created in
   *	 shared memory.
   */
  static void
  bitmap_subplan_mark_shared(Plan *plan)
  {
  	if (IsA(plan, BitmapAnd))
  		bitmap_subplan_mark_shared(
  								   linitial(((BitmapAnd *) plan)->bitmapplans));
  	else if (IsA(plan, BitmapOr))
  	{
  		((BitmapOr *) plan)->isshared = true;
  		bitmap_subplan_mark_shared(
  								   linitial(((BitmapOr *) plan)->bitmapplans));
  	}
  	else if (IsA(plan, BitmapIndexScan))
  		((BitmapIndexScan *) plan)->isshared = true;
  	else
  		elog(ERROR, "unrecognized node type: %d", nodeTag(plan));
  }
  
  /*****************************************************************************
   *
   *	PLAN NODE BUILDING ROUTINES
   *
   * In general, these functions are not passed the original Path and therefore
   * leave it to the caller to fill in the cost/width fields from the Path,
   * typically by calling copy_generic_path_info().  This convention is
   * somewhat historical, but it does support a few places above where we build
   * a plan node without having an exactly corresponding Path node.  Under no
   * circumstances should one of these functions do its own cost calculations,
   * as that would be redundant with calculations done while building Paths.
   *
   *****************************************************************************/
  
  static SeqScan *
  make_seqscan(List *qptlist,
  			 List *qpqual,
  			 Index scanrelid)
  {
  	SeqScan    *node = makeNode(SeqScan);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scanrelid = scanrelid;
  
  	return node;
  }
  
  static SampleScan *
  make_samplescan(List *qptlist,
  				List *qpqual,
  				Index scanrelid,
  				TableSampleClause *tsc)
  {
  	SampleScan *node = makeNode(SampleScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->tablesample = tsc;
  
  	return node;
  }
  
  static IndexScan *
  make_indexscan(List *qptlist,
  			   List *qpqual,
  			   Index scanrelid,
  			   Oid indexid,
  			   List *indexqual,
  			   List *indexqualorig,
  			   List *indexorderby,
  			   List *indexorderbyorig,
  			   List *indexorderbyops,
  			   ScanDirection indexscandir)
  {
  	IndexScan  *node = makeNode(IndexScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->indexid = indexid;
  	node->indexqual = indexqual;
  	node->indexqualorig = indexqualorig;
  	node->indexorderby = indexorderby;
  	node->indexorderbyorig = indexorderbyorig;
  	node->indexorderbyops = indexorderbyops;
  	node->indexorderdir = indexscandir;
  
  	return node;
  }
  
  static IndexOnlyScan *
  make_indexonlyscan(List *qptlist,
  				   List *qpqual,
  				   Index scanrelid,
  				   Oid indexid,
  				   List *indexqual,
  				   List *indexorderby,
  				   List *indextlist,
  				   ScanDirection indexscandir)
  {
  	IndexOnlyScan *node = makeNode(IndexOnlyScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->indexid = indexid;
  	node->indexqual = indexqual;
  	node->indexorderby = indexorderby;
  	node->indextlist = indextlist;
  	node->indexorderdir = indexscandir;
  
  	return node;
  }
  
  static BitmapIndexScan *
  make_bitmap_indexscan(Index scanrelid,
  					  Oid indexid,
  					  List *indexqual,
  					  List *indexqualorig)
  {
  	BitmapIndexScan *node = makeNode(BitmapIndexScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = NIL;		/* not used */
  	plan->qual = NIL;			/* not used */
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->indexid = indexid;
  	node->indexqual = indexqual;
  	node->indexqualorig = indexqualorig;
  
  	return node;
  }
  
  static BitmapHeapScan *
  make_bitmap_heapscan(List *qptlist,
  					 List *qpqual,
  					 Plan *lefttree,
  					 List *bitmapqualorig,
  					 Index scanrelid)
  {
  	BitmapHeapScan *node = makeNode(BitmapHeapScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->bitmapqualorig = bitmapqualorig;
  
  	return node;
  }
  
  static TidScan *
  make_tidscan(List *qptlist,
  			 List *qpqual,
  			 Index scanrelid,
  			 List *tidquals)
  {
  	TidScan    *node = makeNode(TidScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->tidquals = tidquals;
  
  	return node;
  }
  
  static SubqueryScan *
  make_subqueryscan(List *qptlist,
  				  List *qpqual,
  				  Index scanrelid,
  				  Plan *subplan)
  {
  	SubqueryScan *node = makeNode(SubqueryScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->subplan = subplan;
  
  	return node;
  }
  
  static FunctionScan *
  make_functionscan(List *qptlist,
  				  List *qpqual,
  				  Index scanrelid,
  				  List *functions,
  				  bool funcordinality)
  {
  	FunctionScan *node = makeNode(FunctionScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->functions = functions;
  	node->funcordinality = funcordinality;
  
  	return node;
  }
  
  static TableFuncScan *
  make_tablefuncscan(List *qptlist,
  				   List *qpqual,
  				   Index scanrelid,
  				   TableFunc *tablefunc)
  {
  	TableFuncScan *node = makeNode(TableFuncScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->tablefunc = tablefunc;
  
  	return node;
  }
  
  static ValuesScan *
  make_valuesscan(List *qptlist,
  				List *qpqual,
  				Index scanrelid,
  				List *values_lists)
  {
  	ValuesScan *node = makeNode(ValuesScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->values_lists = values_lists;
  
  	return node;
  }
  
  static CteScan *
  make_ctescan(List *qptlist,
  			 List *qpqual,
  			 Index scanrelid,
  			 int ctePlanId,
  			 int cteParam)
  {
  	CteScan    *node = makeNode(CteScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->ctePlanId = ctePlanId;
  	node->cteParam = cteParam;
  
  	return node;
  }
  
  static NamedTuplestoreScan *
  make_namedtuplestorescan(List *qptlist,
  						 List *qpqual,
  						 Index scanrelid,
  						 char *enrname)
  {
  	NamedTuplestoreScan *node = makeNode(NamedTuplestoreScan);
  	Plan	   *plan = &node->scan.plan;
  
  	/* cost should be inserted by caller */
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->enrname = enrname;
  
  	return node;
  }
  
  static WorkTableScan *
  make_worktablescan(List *qptlist,
  				   List *qpqual,
  				   Index scanrelid,
  				   int wtParam)
  {
  	WorkTableScan *node = makeNode(WorkTableScan);
  	Plan	   *plan = &node->scan.plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->wtParam = wtParam;
  
  	return node;
  }
  
  ForeignScan *
  make_foreignscan(List *qptlist,
  				 List *qpqual,
  				 Index scanrelid,
  				 List *fdw_exprs,
  				 List *fdw_private,
  				 List *fdw_scan_tlist,
  				 List *fdw_recheck_quals,
  				 Plan *outer_plan)
  {
  	ForeignScan *node = makeNode(ForeignScan);
  	Plan	   *plan = &node->scan.plan;
  
  	/* cost will be filled in by create_foreignscan_plan */
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = outer_plan;
  	plan->righttree = NULL;
  	node->scan.scanrelid = scanrelid;
  	node->operation = CMD_SELECT;
  	/* fs_server will be filled in by create_foreignscan_plan */
  	node->fs_server = InvalidOid;
  	node->fdw_exprs = fdw_exprs;
  	node->fdw_private = fdw_private;
  	node->fdw_scan_tlist = fdw_scan_tlist;
  	node->fdw_recheck_quals = fdw_recheck_quals;
  	/* fs_relids will be filled in by create_foreignscan_plan */
  	node->fs_relids = NULL;
  	/* fsSystemCol will be filled in by create_foreignscan_plan */
  	node->fsSystemCol = false;
  
  	return node;
  }
  
  static RecursiveUnion *
  make_recursive_union(List *tlist,
  					 Plan *lefttree,
  					 Plan *righttree,
  					 int wtParam,
  					 List *distinctList,
  					 long numGroups)
  {
  	RecursiveUnion *node = makeNode(RecursiveUnion);
  	Plan	   *plan = &node->plan;
  	int			numCols = list_length(distinctList);
  
  	plan->targetlist = tlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = righttree;
  	node->wtParam = wtParam;
  
  	/*
  	 * convert SortGroupClause list into arrays of attr indexes and equality
  	 * operators, as wanted by executor
  	 */
  	node->numCols = numCols;
  	if (numCols > 0)
  	{
  		int			keyno = 0;
  		AttrNumber *dupColIdx;
  		Oid		   *dupOperators;
  		Oid		   *dupCollations;
  		ListCell   *slitem;
  
  		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
  		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
  		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
  
  		foreach(slitem, distinctList)
  		{
  			SortGroupClause *sortcl = (SortGroupClause *) lfirst(slitem);
  			TargetEntry *tle = get_sortgroupclause_tle(sortcl,
  													   plan->targetlist);
  
  			dupColIdx[keyno] = tle->resno;
  			dupOperators[keyno] = sortcl->eqop;
  			dupCollations[keyno] = exprCollation((Node *) tle->expr);
  			Assert(OidIsValid(dupOperators[keyno]));
  			keyno++;
  		}
  		node->dupColIdx = dupColIdx;
  		node->dupOperators = dupOperators;
  		node->dupCollations = dupCollations;
  	}
  	node->numGroups = numGroups;
  
  	return node;
  }
  
  static BitmapAnd *
  make_bitmap_and(List *bitmapplans)
  {
  	BitmapAnd  *node = makeNode(BitmapAnd);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = NIL;
  	plan->qual = NIL;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->bitmapplans = bitmapplans;
  
  	return node;
  }
  
  static BitmapOr *
  make_bitmap_or(List *bitmapplans)
  {
  	BitmapOr   *node = makeNode(BitmapOr);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = NIL;
  	plan->qual = NIL;
  	plan->lefttree = NULL;
  	plan->righttree = NULL;
  	node->bitmapplans = bitmapplans;
  
  	return node;
  }
  
  static NestLoop *
  make_nestloop(List *tlist,
  			  List *joinclauses,
  			  List *otherclauses,
  			  List *nestParams,
  			  Plan *lefttree,
  			  Plan *righttree,
  			  JoinType jointype,
  			  bool inner_unique)
  {
  	NestLoop   *node = makeNode(NestLoop);
  	Plan	   *plan = &node->join.plan;
  
  	plan->targetlist = tlist;
  	plan->qual = otherclauses;
  	plan->lefttree = lefttree;
  	plan->righttree = righttree;
  	node->join.jointype = jointype;
  	node->join.inner_unique = inner_unique;
  	node->join.joinqual = joinclauses;
  	node->nestParams = nestParams;
  
  	return node;
  }
  
  static HashJoin *
  make_hashjoin(List *tlist,
  			  List *joinclauses,
  			  List *otherclauses,
  			  List *hashclauses,
  			  List *hashoperators,
  			  List *hashcollations,
  			  List *hashkeys,
  			  Plan *lefttree,
  			  Plan *righttree,
  			  JoinType jointype,
  			  bool inner_unique)
  {
  	HashJoin   *node = makeNode(HashJoin);
  	Plan	   *plan = &node->join.plan;
  
  	plan->targetlist = tlist;
  	plan->qual = otherclauses;
  	plan->lefttree = lefttree;
  	plan->righttree = righttree;
  	node->hashclauses = hashclauses;
  	node->hashoperators = hashoperators;
  	node->hashcollations = hashcollations;
  	node->hashkeys = hashkeys;
  	node->join.jointype = jointype;
  	node->join.inner_unique = inner_unique;
  	node->join.joinqual = joinclauses;
  
  	return node;
  }
  
  static Hash *
  make_hash(Plan *lefttree,
  		  List *hashkeys,
  		  Oid skewTable,
  		  AttrNumber skewColumn,
  		  bool skewInherit)
  {
  	Hash	   *node = makeNode(Hash);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	node->hashkeys = hashkeys;
  	node->skewTable = skewTable;
  	node->skewColumn = skewColumn;
  	node->skewInherit = skewInherit;
  
  	return node;
  }
  
  static MergeJoin *
  make_mergejoin(List *tlist,
  			   List *joinclauses,
  			   List *otherclauses,
  			   List *mergeclauses,
  			   Oid *mergefamilies,
  			   Oid *mergecollations,
  			   int *mergestrategies,
  			   bool *mergenullsfirst,
  			   Plan *lefttree,
  			   Plan *righttree,
  			   JoinType jointype,
  			   bool inner_unique,
  			   bool skip_mark_restore)
  {
  	MergeJoin  *node = makeNode(MergeJoin);
  	Plan	   *plan = &node->join.plan;
  
  	plan->targetlist = tlist;
  	plan->qual = otherclauses;
  	plan->lefttree = lefttree;
  	plan->righttree = righttree;
  	node->skip_mark_restore = skip_mark_restore;
  	node->mergeclauses = mergeclauses;
  	node->mergeFamilies = mergefamilies;
  	node->mergeCollations = mergecollations;
  	node->mergeStrategies = mergestrategies;
  	node->mergeNullsFirst = mergenullsfirst;
  	node->join.jointype = jointype;
  	node->join.inner_unique = inner_unique;
  	node->join.joinqual = joinclauses;
  
  	return node;
  }
  
  /*
   * make_sort --- basic routine to build a Sort plan node
   *
   * Caller must have built the sortColIdx, sortOperators, collations, and
   * nullsFirst arrays already.
   */
  static Sort *
  make_sort(Plan *lefttree, int numCols,
  		  AttrNumber *sortColIdx, Oid *sortOperators,
  		  Oid *collations, bool *nullsFirst)
  {
  	Sort	   *node = makeNode(Sort);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  	node->numCols = numCols;
  	node->sortColIdx = sortColIdx;
  	node->sortOperators = sortOperators;
  	node->collations = collations;
  	node->nullsFirst = nullsFirst;
  
  	return node;
  }
  
  /*
   * prepare_sort_from_pathkeys
   *	  Prepare to sort according to given pathkeys
   *
   * This is used to set up for Sort, MergeAppend, and Gather Merge nodes.  It
   * calculates the executor's representation of the sort key information, and
   * adjusts the plan targetlist if needed to add resjunk sort columns.
   *
   * Input parameters:
   *	  'lefttree' is the plan node which yields input tuples
   *	  'pathkeys' is the list of pathkeys by which the result is to be sorted
   *	  'relids' identifies the child relation being sorted, if any
   *	  'reqColIdx' is NULL or an array of required sort key column numbers
   *	  'adjust_tlist_in_place' is true if lefttree must be modified in-place
   *
   * We must convert the pathkey information into arrays of sort key column
   * numbers, sort operator OIDs, collation OIDs, and nulls-first flags,
   * which is the representation the executor wants.  These are returned into
   * the output parameters *p_numsortkeys etc.
   *
   * When looking for matches to an EquivalenceClass's members, we will only
   * consider child EC members if they belong to given 'relids'.  This protects
   * against possible incorrect matches to child expressions that contain no
   * Vars.
   *
   * If reqColIdx isn't NULL then it contains sort key column numbers that
   * we should match.  This is used when making child plans for a MergeAppend;
   * it's an error if we can't match the columns.
   *
   * If the pathkeys include expressions that aren't simple Vars, we will
   * usually need to add resjunk items to the input plan's targetlist to
   * compute these expressions, since a Sort or MergeAppend node itself won't
   * do any such calculations.  If the input plan type isn't one that can do
   * projections, this means adding a Result node just to do the projection.
   * However, the caller can pass adjust_tlist_in_place = true to force the
   * lefttree tlist to be modified in-place regardless of whether the node type
   * can project --- we use this for fixing the tlist of MergeAppend itself.
   *
   * Returns the node which is to be the input to the Sort (either lefttree,
   * or a Result stacked atop lefttree).
   */
  static Plan *
  prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
  						   Relids relids,
  						   const AttrNumber *reqColIdx,
  						   bool adjust_tlist_in_place,
  						   int *p_numsortkeys,
  						   AttrNumber **p_sortColIdx,
  						   Oid **p_sortOperators,
  						   Oid **p_collations,
  						   bool **p_nullsFirst)
  {
  	List	   *tlist = lefttree->targetlist;
  	ListCell   *i;
  	int			numsortkeys;
  	AttrNumber *sortColIdx;
  	Oid		   *sortOperators;
  	Oid		   *collations;
  	bool	   *nullsFirst;
  
  	/*
  	 * We will need at most list_length(pathkeys) sort columns; possibly less
  	 */
  	numsortkeys = list_length(pathkeys);
  	sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
  	sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
  	collations = (Oid *) palloc(numsortkeys * sizeof(Oid));
  	nullsFirst = (bool *) palloc(numsortkeys * sizeof(bool));
  
  	numsortkeys = 0;
  
  	foreach(i, pathkeys)
  	{
  		PathKey    *pathkey = (PathKey *) lfirst(i);
  		EquivalenceClass *ec = pathkey->pk_eclass;
  		EquivalenceMember *em;
  		TargetEntry *tle = NULL;
  		Oid			pk_datatype = InvalidOid;
  		Oid			sortop;
  		ListCell   *j;
  
  		if (ec->ec_has_volatile)
  		{
  			/*
  			 * If the pathkey's EquivalenceClass is volatile, then it must
  			 * have come from an ORDER BY clause, and we have to match it to
  			 * that same targetlist entry.
  			 */
  			if (ec->ec_sortref == 0)	/* can't happen */
  				elog(ERROR, "volatile EquivalenceClass has no sortref");
  			tle = get_sortgroupref_tle(ec->ec_sortref, tlist);
  			Assert(tle);
  			Assert(list_length(ec->ec_members) == 1);
  			pk_datatype = ((EquivalenceMember *) linitial(ec->ec_members))->em_datatype;
  		}
  		else if (reqColIdx != NULL)
  		{
  			/*
  			 * If we are given a sort column number to match, only consider
  			 * the single TLE at that position.  It's possible that there is
  			 * no such TLE, in which case fall through and generate a resjunk
  			 * targetentry (we assume this must have happened in the parent
  			 * plan as well).  If there is a TLE but it doesn't match the
  			 * pathkey's EC, we do the same, which is probably the wrong thing
  			 * but we'll leave it to caller to complain about the mismatch.
  			 */
  			tle = get_tle_by_resno(tlist, reqColIdx[numsortkeys]);
  			if (tle)
  			{
  				em = find_ec_member_for_tle(ec, tle, relids);
  				if (em)
  				{
  					/* found expr at right place in tlist */
  					pk_datatype = em->em_datatype;
  				}
  				else
  					tle = NULL;
  			}
  		}
  		else
  		{
  			/*
  			 * Otherwise, we can sort by any non-constant expression listed in
  			 * the pathkey's EquivalenceClass.  For now, we take the first
  			 * tlist item found in the EC. If there's no match, we'll generate
  			 * a resjunk entry using the first EC member that is an expression
  			 * in the input's vars.  (The non-const restriction only matters
  			 * if the EC is below_outer_join; but if it isn't, it won't
  			 * contain consts anyway, else we'd have discarded the pathkey as
  			 * redundant.)
  			 *
  			 * XXX if we have a choice, is there any way of figuring out which
  			 * might be cheapest to execute?  (For example, int4lt is likely
  			 * much cheaper to execute than numericlt, but both might appear
  			 * in the same equivalence class...)  Not clear that we ever will
  			 * have an interesting choice in practice, so it may not matter.
  			 */
  			foreach(j, tlist)
  			{
  				tle = (TargetEntry *) lfirst(j);
  				em = find_ec_member_for_tle(ec, tle, relids);
  				if (em)
  				{
  					/* found expr already in tlist */
  					pk_datatype = em->em_datatype;
  					break;
  				}
  				tle = NULL;
  			}
  		}
  
  		if (!tle)
  		{
  			/*
  			 * No matching tlist item; look for a computable expression. Note
  			 * that we treat Aggrefs as if they were variables; this is
  			 * necessary when attempting to sort the output from an Agg node
  			 * for use in a WindowFunc (since grouping_planner will have
  			 * treated the Aggrefs as variables, too).  Likewise, if we find a
  			 * WindowFunc in a sort expression, treat it as a variable.
  			 */
  			Expr	   *sortexpr = NULL;
  
  			foreach(j, ec->ec_members)
  			{
  				EquivalenceMember *em = (EquivalenceMember *) lfirst(j);
  				List	   *exprvars;
  				ListCell   *k;
  
  				/*
  				 * We shouldn't be trying to sort by an equivalence class that
  				 * contains a constant, so no need to consider such cases any
  				 * further.
  				 */
  				if (em->em_is_const)
  					continue;
  
  				/*
  				 * Ignore child members unless they belong to the rel being
  				 * sorted.
  				 */
  				if (em->em_is_child &&
  					!bms_is_subset(em->em_relids, relids))
  					continue;
  
  				sortexpr = em->em_expr;
  				exprvars = pull_var_clause((Node *) sortexpr,
  										   PVC_INCLUDE_AGGREGATES |
  										   PVC_INCLUDE_WINDOWFUNCS |
  										   PVC_INCLUDE_PLACEHOLDERS);
  				foreach(k, exprvars)
  				{
  					if (!tlist_member_ignore_relabel(lfirst(k), tlist))
  						break;
  				}
  				list_free(exprvars);
  				if (!k)
  				{
  					pk_datatype = em->em_datatype;
  					break;		/* found usable expression */
  				}
  			}
  			if (!j)
  				elog(ERROR, "could not find pathkey item to sort");
  
  			/*
  			 * Do we need to insert a Result node?
  			 */
  			if (!adjust_tlist_in_place &&
  				!is_projection_capable_plan(lefttree))
  			{
  				/* copy needed so we don't modify input's tlist below */
  				tlist = copyObject(tlist);
  				lefttree = inject_projection_plan(lefttree, tlist,
  												  lefttree->parallel_safe);
  			}
  
  			/* Don't bother testing is_projection_capable_plan again */
  			adjust_tlist_in_place = true;
  
  			/*
  			 * Add resjunk entry to input's tlist
  			 */
  			tle = makeTargetEntry(sortexpr,
  								  list_length(tlist) + 1,
  								  NULL,
  								  true);
  			tlist = lappend(tlist, tle);
  			lefttree->targetlist = tlist;	/* just in case NIL before */
  		}
  
  		/*
  		 * Look up the correct sort operator from the PathKey's slightly
  		 * abstracted representation.
  		 */
  		sortop = get_opfamily_member(pathkey->pk_opfamily,
  									 pk_datatype,
  									 pk_datatype,
  									 pathkey->pk_strategy);
  		if (!OidIsValid(sortop))	/* should not happen */
  			elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
  				 pathkey->pk_strategy, pk_datatype, pk_datatype,
  				 pathkey->pk_opfamily);
  
  		/* Add the column to the sort arrays */
  		sortColIdx[numsortkeys] = tle->resno;
  		sortOperators[numsortkeys] = sortop;
  		collations[numsortkeys] = ec->ec_collation;
  		nullsFirst[numsortkeys] = pathkey->pk_nulls_first;
  		numsortkeys++;
  	}
  
  	/* Return results */
  	*p_numsortkeys = numsortkeys;
  	*p_sortColIdx = sortColIdx;
  	*p_sortOperators = sortOperators;
  	*p_collations = collations;
  	*p_nullsFirst = nullsFirst;
  
  	return lefttree;
  }
  
  /*
   * find_ec_member_for_tle
   *		Locate an EquivalenceClass member matching the given TLE, if any
   *
   * Child EC members are ignored unless they belong to given 'relids'.
   */
  static EquivalenceMember *
  find_ec_member_for_tle(EquivalenceClass *ec,
  					   TargetEntry *tle,
  					   Relids relids)
  {
  	Expr	   *tlexpr;
  	ListCell   *lc;
  
  	/* We ignore binary-compatible relabeling on both ends */
  	tlexpr = tle->expr;
  	while (tlexpr && IsA(tlexpr, RelabelType))
  		tlexpr = ((RelabelType *) tlexpr)->arg;
  
  	foreach(lc, ec->ec_members)
  	{
  		EquivalenceMember *em = (EquivalenceMember *) lfirst(lc);
  		Expr	   *emexpr;
  
  		/*
  		 * We shouldn't be trying to sort by an equivalence class that
  		 * contains a constant, so no need to consider such cases any further.
  		 */
  		if (em->em_is_const)
  			continue;
  
  		/*
  		 * Ignore child members unless they belong to the rel being sorted.
  		 */
  		if (em->em_is_child &&
  			!bms_is_subset(em->em_relids, relids))
  			continue;
  
  		/* Match if same expression (after stripping relabel) */
  		emexpr = em->em_expr;
  		while (emexpr && IsA(emexpr, RelabelType))
  			emexpr = ((RelabelType *) emexpr)->arg;
  
  		if (equal(emexpr, tlexpr))
  			return em;
  	}
  
  	return NULL;
  }
  
  /*
   * make_sort_from_pathkeys
   *	  Create sort plan to sort according to given pathkeys
   *
   *	  'lefttree' is the node which yields input tuples
   *	  'pathkeys' is the list of pathkeys by which the result is to be sorted
   *	  'relids' is the set of relations required by prepare_sort_from_pathkeys()
   */
  static Sort *
  make_sort_from_pathkeys(Plan *lefttree, List *pathkeys, Relids relids)
  {
  	int			numsortkeys;
  	AttrNumber *sortColIdx;
  	Oid		   *sortOperators;
  	Oid		   *collations;
  	bool	   *nullsFirst;
  
  	/* Compute sort column info, and adjust lefttree as needed */
  	lefttree = prepare_sort_from_pathkeys(lefttree, pathkeys,
  										  relids,
  										  NULL,
  										  false,
  										  &numsortkeys,
  										  &sortColIdx,
  										  &sortOperators,
  										  &collations,
  										  &nullsFirst);
  
  	/* Now build the Sort node */
  	return make_sort(lefttree, numsortkeys,
  					 sortColIdx, sortOperators,
  					 collations, nullsFirst);
  }
  
  /*
   * make_sort_from_sortclauses
   *	  Create sort plan to sort according to given sortclauses
   *
   *	  'sortcls' is a list of SortGroupClauses
   *	  'lefttree' is the node which yields input tuples
   */
  Sort *
  make_sort_from_sortclauses(List *sortcls, Plan *lefttree)
  {
  	List	   *sub_tlist = lefttree->targetlist;
  	ListCell   *l;
  	int			numsortkeys;
  	AttrNumber *sortColIdx;
  	Oid		   *sortOperators;
  	Oid		   *collations;
  	bool	   *nullsFirst;
  
  	/* Convert list-ish representation to arrays wanted by executor */
  	numsortkeys = list_length(sortcls);
  	sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
  	sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
  	collations = (Oid *) palloc(numsortkeys * sizeof(Oid));
  	nullsFirst = (bool *) palloc(numsortkeys * sizeof(bool));
  
  	numsortkeys = 0;
  	foreach(l, sortcls)
  	{
  		SortGroupClause *sortcl = (SortGroupClause *) lfirst(l);
  		TargetEntry *tle = get_sortgroupclause_tle(sortcl, sub_tlist);
  
  		sortColIdx[numsortkeys] = tle->resno;
  		sortOperators[numsortkeys] = sortcl->sortop;
  		collations[numsortkeys] = exprCollation((Node *) tle->expr);
  		nullsFirst[numsortkeys] = sortcl->nulls_first;
  		numsortkeys++;
  	}
  
  	return make_sort(lefttree, numsortkeys,
  					 sortColIdx, sortOperators,
  					 collations, nullsFirst);
  }
  
  /*
   * make_sort_from_groupcols
   *	  Create sort plan to sort based on grouping columns
   *
   * 'groupcls' is the list of SortGroupClauses
   * 'grpColIdx' gives the column numbers to use
   *
   * This might look like it could be merged with make_sort_from_sortclauses,
   * but presently we *must* use the grpColIdx[] array to locate sort columns,
   * because the child plan's tlist is not marked with ressortgroupref info
   * appropriate to the grouping node.  So, only the sort ordering info
   * is used from the SortGroupClause entries.
   */
  static Sort *
  make_sort_from_groupcols(List *groupcls,
  						 AttrNumber *grpColIdx,
  						 Plan *lefttree)
  {
  	List	   *sub_tlist = lefttree->targetlist;
  	ListCell   *l;
  	int			numsortkeys;
  	AttrNumber *sortColIdx;
  	Oid		   *sortOperators;
  	Oid		   *collations;
  	bool	   *nullsFirst;
  
  	/* Convert list-ish representation to arrays wanted by executor */
  	numsortkeys = list_length(groupcls);
  	sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
  	sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
  	collations = (Oid *) palloc(numsortkeys * sizeof(Oid));
  	nullsFirst = (bool *) palloc(numsortkeys * sizeof(bool));
  
  	numsortkeys = 0;
  	foreach(l, groupcls)
  	{
  		SortGroupClause *grpcl = (SortGroupClause *) lfirst(l);
  		TargetEntry *tle = get_tle_by_resno(sub_tlist, grpColIdx[numsortkeys]);
  
  		if (!tle)
  			elog(ERROR, "could not retrieve tle for sort-from-groupcols");
  
  		sortColIdx[numsortkeys] = tle->resno;
  		sortOperators[numsortkeys] = grpcl->sortop;
  		collations[numsortkeys] = exprCollation((Node *) tle->expr);
  		nullsFirst[numsortkeys] = grpcl->nulls_first;
  		numsortkeys++;
  	}
  
  	return make_sort(lefttree, numsortkeys,
  					 sortColIdx, sortOperators,
  					 collations, nullsFirst);
  }
  
  static Material *
  make_material(Plan *lefttree)
  {
  	Material   *node = makeNode(Material);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	return node;
  }
  
  /*
   * materialize_finished_plan: stick a Material node atop a completed plan
   *
   * There are a couple of places where we want to attach a Material node
   * after completion of create_plan(), without any MaterialPath path.
   * Those places should probably be refactored someday to do this on the
   * Path representation, but it's not worth the trouble yet.
   */
  Plan *
  materialize_finished_plan(Plan *subplan)
  {
  	Plan	   *matplan;
  	Path		matpath;		/* dummy for result of cost_material */
  
  	matplan = (Plan *) make_material(subplan);
  
  	/*
  	 * XXX horrid kluge: if there are any initPlans attached to the subplan,
  	 * move them up to the Material node, which is now effectively the top
  	 * plan node in its query level.  This prevents failure in
  	 * SS_finalize_plan(), which see for comments.  We don't bother adjusting
  	 * the subplan's cost estimate for this.
  	 */
  	matplan->initPlan = subplan->initPlan;
  	subplan->initPlan = NIL;
  
  	/* Set cost data */
  	cost_material(&matpath,
  				  subplan->startup_cost,
  				  subplan->total_cost,
  				  subplan->plan_rows,
  				  subplan->plan_width);
  	matplan->startup_cost = matpath.startup_cost;
  	matplan->total_cost = matpath.total_cost;
  	matplan->plan_rows = subplan->plan_rows;
  	matplan->plan_width = subplan->plan_width;
  	matplan->parallel_aware = false;
  	matplan->parallel_safe = subplan->parallel_safe;
  
  	return matplan;
  }
  
  Agg *
  make_agg(List *tlist, List *qual,
  		 AggStrategy aggstrategy, AggSplit aggsplit,
  		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
  		 List *groupingSets, List *chain,
  		 double dNumGroups, Plan *lefttree)
  {
  	Agg		   *node = makeNode(Agg);
  	Plan	   *plan = &node->plan;
  	long		numGroups;
  
  	/* Reduce to long, but 'ware overflow! */
  	numGroups = (long) Min(dNumGroups, (double) LONG_MAX);
  
  	node->aggstrategy = aggstrategy;
  	node->aggsplit = aggsplit;
  	node->numCols = numGroupCols;
  	node->grpColIdx = grpColIdx;
  	node->grpOperators = grpOperators;
  	node->grpCollations = grpCollations;
  	node->numGroups = numGroups;
  	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
  	node->groupingSets = groupingSets;
  	node->chain = chain;
  
  	plan->qual = qual;
  	plan->targetlist = tlist;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	return node;
  }
  
  static WindowAgg *
  make_windowagg(List *tlist, Index winref,
  			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
  			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
  			   int frameOptions, Node *startOffset, Node *endOffset,
  			   Oid startInRangeFunc, Oid endInRangeFunc,
  			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
  			   Plan *lefttree)
  {
  	WindowAgg  *node = makeNode(WindowAgg);
  	Plan	   *plan = &node->plan;
  
  	node->winref = winref;
  	node->partNumCols = partNumCols;
  	node->partColIdx = partColIdx;
  	node->partOperators = partOperators;
  	node->partCollations = partCollations;
  	node->ordNumCols = ordNumCols;
  	node->ordColIdx = ordColIdx;
  	node->ordOperators = ordOperators;
  	node->ordCollations = ordCollations;
  	node->frameOptions = frameOptions;
  	node->startOffset = startOffset;
  	node->endOffset = endOffset;
  	node->startInRangeFunc = startInRangeFunc;
  	node->endInRangeFunc = endInRangeFunc;
  	node->inRangeColl = inRangeColl;
  	node->inRangeAsc = inRangeAsc;
  	node->inRangeNullsFirst = inRangeNullsFirst;
  
  	plan->targetlist = tlist;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  	/* WindowAgg nodes never have a qual clause */
  	plan->qual = NIL;
  
  	return node;
  }
  
  static Group *
  make_group(List *tlist,
  		   List *qual,
  		   int numGroupCols,
  		   AttrNumber *grpColIdx,
  		   Oid *grpOperators,
  		   Oid *grpCollations,
  		   Plan *lefttree)
  {
  	Group	   *node = makeNode(Group);
  	Plan	   *plan = &node->plan;
  
  	node->numCols = numGroupCols;
  	node->grpColIdx = grpColIdx;
  	node->grpOperators = grpOperators;
  	node->grpCollations = grpCollations;
  
  	plan->qual = qual;
  	plan->targetlist = tlist;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	return node;
  }
  
  /*
   * distinctList is a list of SortGroupClauses, identifying the targetlist items
   * that should be considered by the Unique filter.  The input path must
   * already be sorted accordingly.
   */
  static Unique *
  make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
  {
  	Unique	   *node = makeNode(Unique);
  	Plan	   *plan = &node->plan;
  	int			numCols = list_length(distinctList);
  	int			keyno = 0;
  	AttrNumber *uniqColIdx;
  	Oid		   *uniqOperators;
  	Oid		   *uniqCollations;
  	ListCell   *slitem;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	/*
  	 * convert SortGroupClause list into arrays of attr indexes and equality
  	 * operators, as wanted by executor
  	 */
  	Assert(numCols > 0);
  	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
  	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
  	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
  
  	foreach(slitem, distinctList)
  	{
  		SortGroupClause *sortcl = (SortGroupClause *) lfirst(slitem);
  		TargetEntry *tle = get_sortgroupclause_tle(sortcl, plan->targetlist);
  
  		uniqColIdx[keyno] = tle->resno;
  		uniqOperators[keyno] = sortcl->eqop;
  		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
  		Assert(OidIsValid(uniqOperators[keyno]));
  		keyno++;
  	}
  
  	node->numCols = numCols;
  	node->uniqColIdx = uniqColIdx;
  	node->uniqOperators = uniqOperators;
  	node->uniqCollations = uniqCollations;
  
  	return node;
  }
  
  /*
   * as above, but use pathkeys to identify the sort columns and semantics
   */
  static Unique *
  make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
  {
  	Unique	   *node = makeNode(Unique);
  	Plan	   *plan = &node->plan;
  	int			keyno = 0;
  	AttrNumber *uniqColIdx;
  	Oid		   *uniqOperators;
  	Oid		   *uniqCollations;
  	ListCell   *lc;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	/*
  	 * Convert pathkeys list into arrays of attr indexes and equality
  	 * operators, as wanted by executor.  This has a lot in common with
  	 * prepare_sort_from_pathkeys ... maybe unify sometime?
  	 */
  	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
  	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
  	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
  	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
  
  	foreach(lc, pathkeys)
  	{
  		PathKey    *pathkey = (PathKey *) lfirst(lc);
  		EquivalenceClass *ec = pathkey->pk_eclass;
  		EquivalenceMember *em;
  		TargetEntry *tle = NULL;
  		Oid			pk_datatype = InvalidOid;
  		Oid			eqop;
  		ListCell   *j;
  
  		/* Ignore pathkeys beyond the specified number of columns */
  		if (keyno >= numCols)
  			break;
  
  		if (ec->ec_has_volatile)
  		{
  			/*
  			 * If the pathkey's EquivalenceClass is volatile, then it must
  			 * have come from an ORDER BY clause, and we have to match it to
  			 * that same targetlist entry.
  			 */
  			if (ec->ec_sortref == 0)	/* can't happen */
  				elog(ERROR, "volatile EquivalenceClass has no sortref");
  			tle = get_sortgroupref_tle(ec->ec_sortref, plan->targetlist);
  			Assert(tle);
  			Assert(list_length(ec->ec_members) == 1);
  			pk_datatype = ((EquivalenceMember *) linitial(ec->ec_members))->em_datatype;
  		}
  		else
  		{
  			/*
  			 * Otherwise, we can use any non-constant expression listed in the
  			 * pathkey's EquivalenceClass.  For now, we take the first tlist
  			 * item found in the EC.
  			 */
  			foreach(j, plan->targetlist)
  			{
  				tle = (TargetEntry *) lfirst(j);
  				em = find_ec_member_for_tle(ec, tle, NULL);
  				if (em)
  				{
  					/* found expr already in tlist */
  					pk_datatype = em->em_datatype;
  					break;
  				}
  				tle = NULL;
  			}
  		}
  
  		if (!tle)
  			elog(ERROR, "could not find pathkey item to sort");
  
  		/*
  		 * Look up the correct equality operator from the PathKey's slightly
  		 * abstracted representation.
  		 */
  		eqop = get_opfamily_member(pathkey->pk_opfamily,
  								   pk_datatype,
  								   pk_datatype,
  								   BTEqualStrategyNumber);
  		if (!OidIsValid(eqop))	/* should not happen */
  			elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
  				 BTEqualStrategyNumber, pk_datatype, pk_datatype,
  				 pathkey->pk_opfamily);
  
  		uniqColIdx[keyno] = tle->resno;
  		uniqOperators[keyno] = eqop;
  		uniqCollations[keyno] = ec->ec_collation;
  
  		keyno++;
  	}
  
  	node->numCols = numCols;
  	node->uniqColIdx = uniqColIdx;
  	node->uniqOperators = uniqOperators;
  	node->uniqCollations = uniqCollations;
  
  	return node;
  }
  
  static Gather *
  make_gather(List *qptlist,
  			List *qpqual,
  			int nworkers,
  			int rescan_param,
  			bool single_copy,
  			Plan *subplan)
  {
  	Gather	   *node = makeNode(Gather);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = qptlist;
  	plan->qual = qpqual;
  	plan->lefttree = subplan;
  	plan->righttree = NULL;
  	node->num_workers = nworkers;
  	node->rescan_param = rescan_param;
  	node->single_copy = single_copy;
  	node->invisible = false;
  	node->initParam = NULL;
  
  	return node;
  }
  
  /*
   * distinctList is a list of SortGroupClauses, identifying the targetlist
   * items that should be considered by the SetOp filter.  The input path must
   * already be sorted accordingly.
   */
  static SetOp *
  make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
  		   List *distinctList, AttrNumber flagColIdx, int firstFlag,
  		   long numGroups)
  {
  	SetOp	   *node = makeNode(SetOp);
  	Plan	   *plan = &node->plan;
  	int			numCols = list_length(distinctList);
  	int			keyno = 0;
  	AttrNumber *dupColIdx;
  	Oid		   *dupOperators;
  	Oid		   *dupCollations;
  	ListCell   *slitem;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	/*
  	 * convert SortGroupClause list into arrays of attr indexes and equality
  	 * operators, as wanted by executor
  	 */
  	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
  	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
  	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
  
  	foreach(slitem, distinctList)
  	{
  		SortGroupClause *sortcl = (SortGroupClause *) lfirst(slitem);
  		TargetEntry *tle = get_sortgroupclause_tle(sortcl, plan->targetlist);
  
  		dupColIdx[keyno] = tle->resno;
  		dupOperators[keyno] = sortcl->eqop;
  		dupCollations[keyno] = exprCollation((Node *) tle->expr);
  		Assert(OidIsValid(dupOperators[keyno]));
  		keyno++;
  	}
  
  	node->cmd = cmd;
  	node->strategy = strategy;
  	node->numCols = numCols;
  	node->dupColIdx = dupColIdx;
  	node->dupOperators = dupOperators;
  	node->dupCollations = dupCollations;
  	node->flagColIdx = flagColIdx;
  	node->firstFlag = firstFlag;
  	node->numGroups = numGroups;
  
  	return node;
  }
  
  /*
   * make_lockrows
   *	  Build a LockRows plan node
   */
  static LockRows *
  make_lockrows(Plan *lefttree, List *rowMarks, int epqParam)
  {
  	LockRows   *node = makeNode(LockRows);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	node->rowMarks = rowMarks;
  	node->epqParam = epqParam;
  
  	return node;
  }
  
  /*
   * make_limit
   *	  Build a Limit plan node
   */
  Limit *
  make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount)
  {
  	Limit	   *node = makeNode(Limit);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = lefttree->targetlist;
  	plan->qual = NIL;
  	plan->lefttree = lefttree;
  	plan->righttree = NULL;
  
  	node->limitOffset = limitOffset;
  	node->limitCount = limitCount;
  
  	return node;
  }
  
  /*
   * make_result
   *	  Build a Result plan node
   */
  static Result *
  make_result(List *tlist,
  			Node *resconstantqual,
  			Plan *subplan)
  {
  	Result	   *node = makeNode(Result);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = tlist;
  	plan->qual = NIL;
  	plan->lefttree = subplan;
  	plan->righttree = NULL;
  	node->resconstantqual = resconstantqual;
  
  	return node;
  }
  
  /*
   * make_project_set
   *	  Build a ProjectSet plan node
   */
  static ProjectSet *
  make_project_set(List *tlist,
  				 Plan *subplan)
  {
  	ProjectSet *node = makeNode(ProjectSet);
  	Plan	   *plan = &node->plan;
  
  	plan->targetlist = tlist;
  	plan->qual = NIL;
  	plan->lefttree = subplan;
  	plan->righttree = NULL;
  
  	return node;
  }
  
  /*
   * make_modifytable
   *	  Build a ModifyTable plan node
   */
  static ModifyTable *
  make_modifytable(PlannerInfo *root,
  				 CmdType operation, bool canSetTag,
  				 Index nominalRelation, Index rootRelation,
  				 bool partColsUpdated,
  				 List *resultRelations, List *subplans, List *subroots,
  				 List *withCheckOptionLists, List *returningLists,
  				 List *rowMarks, OnConflictExpr *onconflict, int epqParam)
  {
  	ModifyTable *node = makeNode(ModifyTable);
  	List	   *fdw_private_list;
  	Bitmapset  *direct_modify_plans;
  	ListCell   *lc;
  	ListCell   *lc2;
  	int			i;
  
  	Assert(list_length(resultRelations) == list_length(subplans));
  	Assert(list_length(resultRelations) == list_length(subroots));
  	Assert(withCheckOptionLists == NIL ||
  		   list_length(resultRelations) == list_length(withCheckOptionLists));
  	Assert(returningLists == NIL ||
  		   list_length(resultRelations) == list_length(returningLists));
  
  	node->plan.lefttree = NULL;
  	node->plan.righttree = NULL;
  	node->plan.qual = NIL;
  	/* setrefs.c will fill in the targetlist, if needed */
  	node->plan.targetlist = NIL;
  
  	node->operation = operation;
  	node->canSetTag = canSetTag;
  	node->nominalRelation = nominalRelation;
  	node->rootRelation = rootRelation;
  	node->partColsUpdated = partColsUpdated;
  	node->resultRelations = resultRelations;
  	node->resultRelIndex = -1;	/* will be set correctly in setrefs.c */
  	node->rootResultRelIndex = -1;	/* will be set correctly in setrefs.c */
  	node->plans = subplans;
  	if (!onconflict)
  	{
  		node->onConflictAction = ONCONFLICT_NONE;
  		node->onConflictSet = NIL;
  		node->onConflictWhere = NULL;
  		node->arbiterIndexes = NIL;
  		node->exclRelRTI = 0;
  		node->exclRelTlist = NIL;
  	}
  	else
  	{
  		node->onConflictAction = onconflict->action;
  		node->onConflictSet = onconflict->onConflictSet;
  		node->onConflictWhere = onconflict->onConflictWhere;
  
  		/*
  		 * If a set of unique index inference elements was provided (an
  		 * INSERT...ON CONFLICT "inference specification"), then infer
  		 * appropriate unique indexes (or throw an error if none are
  		 * available).
  		 */
  		node->arbiterIndexes = infer_arbiter_indexes(root);
  
  		node->exclRelRTI = onconflict->exclRelIndex;
  		node->exclRelTlist = onconflict->exclRelTlist;
  	}
  	node->withCheckOptionLists = withCheckOptionLists;
  	node->returningLists = returningLists;
  	node->rowMarks = rowMarks;
  	node->epqParam = epqParam;
  
  	/*
  	 * For each result relation that is a foreign table, allow the FDW to
  	 * construct private plan data, and accumulate it all into a list.
  	 */
  	fdw_private_list = NIL;
  	direct_modify_plans = NULL;
  	i = 0;
  	forboth(lc, resultRelations, lc2, subroots)
  	{
  		Index		rti = lfirst_int(lc);
  		PlannerInfo *subroot = lfirst_node(PlannerInfo, lc2);
  		FdwRoutine *fdwroutine;
  		List	   *fdw_private;
  		bool		direct_modify;
  
  		/*
  		 * If possible, we want to get the FdwRoutine from our RelOptInfo for
  		 * the table.  But sometimes we don't have a RelOptInfo and must get
  		 * it the hard way.  (In INSERT, the target relation is not scanned,
  		 * so it's not a baserel; and there are also corner cases for
  		 * updatable views where the target rel isn't a baserel.)
  		 */
  		if (rti < subroot->simple_rel_array_size &&
  			subroot->simple_rel_array[rti] != NULL)
  		{
  			RelOptInfo *resultRel = subroot->simple_rel_array[rti];
  
  			fdwroutine = resultRel->fdwroutine;
  		}
  		else
  		{
  			RangeTblEntry *rte = planner_rt_fetch(rti, subroot);
  
  			Assert(rte->rtekind == RTE_RELATION);
  			if (rte->relkind == RELKIND_FOREIGN_TABLE)
  				fdwroutine = GetFdwRoutineByRelId(rte->relid);
  			else
  				fdwroutine = NULL;
  		}
  
  		/*
  		 * Try to modify the foreign table directly if (1) the FDW provides
  		 * callback functions needed for that and (2) there are no local
  		 * structures that need to be run for each modified row: row-level
  		 * triggers on the foreign table, stored generated columns, WITH CHECK
  		 * OPTIONs from parent views.
  		 */
  		direct_modify = false;
  		if (fdwroutine != NULL &&
  			fdwroutine->PlanDirectModify != NULL &&
  			fdwroutine->BeginDirectModify != NULL &&
  			fdwroutine->IterateDirectModify != NULL &&
  			fdwroutine->EndDirectModify != NULL &&
  			withCheckOptionLists == NIL &&
  			!has_row_triggers(subroot, rti, operation) &&
  			!has_stored_generated_columns(subroot, rti))
  			direct_modify = fdwroutine->PlanDirectModify(subroot, node, rti, i);
  		if (direct_modify)
  			direct_modify_plans = bms_add_member(direct_modify_plans, i);
  
  		if (!direct_modify &&
  			fdwroutine != NULL &&
  			fdwroutine->PlanForeignModify != NULL)
  			fdw_private = fdwroutine->PlanForeignModify(subroot, node, rti, i);
  		else
  			fdw_private = NIL;
  		fdw_private_list = lappend(fdw_private_list, fdw_private);
  		i++;
  	}
  	node->fdwPrivLists = fdw_private_list;
  	node->fdwDirectModifyPlans = direct_modify_plans;
  
  	return node;
  }
  
  /*
   * is_projection_capable_path
   *		Check whether a given Path node is able to do projection.
   */
  bool
  is_projection_capable_path(Path *path)
  {
  	/* Most plan types can project, so just list the ones that can't */
  	switch (path->pathtype)
  	{
  		case T_Hash:
  		case T_Material:
  		case T_Sort:
  		case T_Unique:
  		case T_SetOp:
  		case T_LockRows:
  		case T_Limit:
  		case T_ModifyTable:
  		case T_MergeAppend:
  		case T_RecursiveUnion:
  			return false;
  		case T_Append:
  
  			/*
  			 * Append can't project, but if an AppendPath is being used to
  			 * represent a dummy path, what will actually be generated is a
  			 * Result which can project.
  			 */
  			return IS_DUMMY_APPEND(path);
  		case T_ProjectSet:
  
  			/*
  			 * Although ProjectSet certainly projects, say "no" because we
  			 * don't want the planner to randomly replace its tlist with
  			 * something else; the SRFs have to stay at top level.  This might
  			 * get relaxed later.
  			 */
  			return false;
  		default:
  			break;
  	}
  	return true;
  }
  
  /*
   * is_projection_capable_plan
   *		Check whether a given Plan node is able to do projection.
   */
  bool
  is_projection_capable_plan(Plan *plan)
  {
  	/* Most plan types can project, so just list the ones that can't */
  	switch (nodeTag(plan))
  	{
  		case T_Hash:
  		case T_Material:
  		case T_Sort:
  		case T_Unique:
  		case T_SetOp:
  		case T_LockRows:
  		case T_Limit:
  		case T_ModifyTable:
  		case T_Append:
  		case T_MergeAppend:
  		case T_RecursiveUnion:
  			return false;
  		case T_ProjectSet:
  
  			/*
  			 * Although ProjectSet certainly projects, say "no" because we
  			 * don't want the planner to randomly replace its tlist with
  			 * something else; the SRFs have to stay at top level.  This might
  			 * get relaxed later.
  			 */
  			return false;
  		default:
  			break;
  	}
  	return true;
  }
  