text: /*-------------------------------------------------------------------------
   *
   * setrefs.c
   *	  Post-processing of a completed plan tree: fix references to subplan
   *	  vars, compute regproc values for operators, etc
   *
   * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/optimizer/plan/setrefs.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "access/transam.h"
  #include "catalog/pg_type.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/pathnode.h"
  #include "optimizer/planmain.h"
  #include "optimizer/planner.h"
  #include "optimizer/tlist.h"
  #include "tcop/utility.h"
  #include "utils/lsyscache.h"
  #include "utils/syscache.h"
  
  
  typedef struct
  {
  	Index		varno;			/* RT index of Var */
  	AttrNumber	varattno;		/* attr number of Var */
  	AttrNumber	resno;			/* TLE position of Var */
  } tlist_vinfo;
  
  typedef struct
  {
  	List	   *tlist;			/* underlying target list */
  	int			num_vars;		/* number of plain Var tlist entries */
  	bool		has_ph_vars;	/* are there PlaceHolderVar entries? */
  	bool		has_non_vars;	/* are there other entries? */
  	/* array of num_vars entries: */
  	tlist_vinfo vars[1];		/* VARIABLE LENGTH ARRAY */
  } indexed_tlist;				/* VARIABLE LENGTH STRUCT */
  
  typedef struct
  {
  	PlannerInfo *root;
  	int			rtoffset;
  } fix_scan_expr_context;
  
  typedef struct
  {
  	PlannerInfo *root;
  	indexed_tlist *outer_itlist;
  	indexed_tlist *inner_itlist;
  	Index		acceptable_rel;
  	int			rtoffset;
  } fix_join_expr_context;
  
  typedef struct
  {
  	PlannerInfo *root;
  	indexed_tlist *subplan_itlist;
  	Index		newvarno;
  	int			rtoffset;
  } fix_upper_expr_context;
  
  /*
   * Check if a Const node is a regclass value.  We accept plain OID too,
   * since a regclass Const will get folded to that type if it's an argument
   * to oideq or similar operators.  (This might result in some extraneous
   * values in a plan's list of relation dependencies, but the worst result
   * would be occasional useless replans.)
   */
  #define ISREGCLASSCONST(con) \
  	(((con)->consttype == REGCLASSOID || (con)->consttype == OIDOID) && \
  	 !(con)->constisnull)
  
  #define fix_scan_list(root, lst, rtoffset) \
  	((List *) fix_scan_expr(root, (Node *) (lst), rtoffset))
  
  static void add_rtes_to_flat_rtable(PlannerInfo *root, bool recursing);
  static void flatten_unplanned_rtes(PlannerGlobal *glob, RangeTblEntry *rte);
  static bool flatten_rtes_walker(Node *node, PlannerGlobal *glob);
  static void add_rte_to_flat_rtable(PlannerGlobal *glob, RangeTblEntry *rte);
  static Plan *set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset);
  static Plan *set_indexonlyscan_references(PlannerInfo *root,
  							 IndexOnlyScan *plan,
  							 int rtoffset);
  static Plan *set_subqueryscan_references(PlannerInfo *root,
  							SubqueryScan *plan,
  							int rtoffset);
  static bool trivial_subqueryscan(SubqueryScan *plan);
  static Node *fix_scan_expr(PlannerInfo *root, Node *node, int rtoffset);
  static Node *fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context);
  static bool fix_scan_expr_walker(Node *node, fix_scan_expr_context *context);
  static void set_join_references(PlannerInfo *root, Join *join, int rtoffset);
  static void set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset);
  static void set_dummy_tlist_references(Plan *plan, int rtoffset);
  static indexed_tlist *build_tlist_index(List *tlist);
  static Var *search_indexed_tlist_for_var(Var *var,
  							 indexed_tlist *itlist,
  							 Index newvarno,
  							 int rtoffset);
  static Var *search_indexed_tlist_for_non_var(Node *node,
  								 indexed_tlist *itlist,
  								 Index newvarno);
  static Var *search_indexed_tlist_for_sortgroupref(Node *node,
  									  Index sortgroupref,
  									  indexed_tlist *itlist,
  									  Index newvarno);
  static List *fix_join_expr(PlannerInfo *root,
  			  List *clauses,
  			  indexed_tlist *outer_itlist,
  			  indexed_tlist *inner_itlist,
  			  Index acceptable_rel, int rtoffset);
  static Node *fix_join_expr_mutator(Node *node,
  					  fix_join_expr_context *context);
  static Node *fix_upper_expr(PlannerInfo *root,
  			   Node *node,
  			   indexed_tlist *subplan_itlist,
  			   Index newvarno,
  			   int rtoffset);
  static Node *fix_upper_expr_mutator(Node *node,
  					   fix_upper_expr_context *context);
  static List *set_returning_clause_references(PlannerInfo *root,
  								List *rlist,
  								Plan *topplan,
  								Index resultRelation,
  								int rtoffset);
  static bool fix_opfuncids_walker(Node *node, void *context);
  static bool extract_query_dependencies_walker(Node *node,
  								  PlannerInfo *context);
  
  
  /*****************************************************************************
   *
   *		SUBPLAN REFERENCES
   *
   *****************************************************************************/
  
  /*
   * set_plan_references
   *
   * This is the final processing pass of the planner/optimizer.	The plan
   * tree is complete; we just have to adjust some representational details
   * for the convenience of the executor:
   *
   * 1. We flatten the various subquery rangetables into a single list, and
   * zero out RangeTblEntry fields that are not useful to the executor.
   *
   * 2. We adjust Vars in scan nodes to be consistent with the flat rangetable.
   *
   * 3. We adjust Vars in upper plan nodes to refer to the outputs of their
   * subplans.
   *
   * 4. We compute regproc OIDs for operators (ie, we look up the function
   * that implements each op).
   *
   * 5. We create lists of specific objects that the plan depends on.
   * This will be used by plancache.c to drive invalidation of cached plans.
   * Relation dependencies are represented by OIDs, and everything else by
   * PlanInvalItems (this distinction is motivated by the shared-inval APIs).
   * Currently, relations and user-defined functions are the only types of
   * objects that are explicitly tracked this way.
   *
   * We also perform one final optimization step, which is to delete
   * SubqueryScan plan nodes that aren't doing anything useful (ie, have
   * no qual and a no-op targetlist).  The reason for doing this last is that
   * it can't readily be done before set_plan_references, because it would
   * break set_upper_references: the Vars in the subquery's top tlist
   * wouldn't match up with the Vars in the outer plan tree.  The SubqueryScan
   * serves a necessary function as a buffer between outer query and subquery
   * variable numbering ... but after we've flattened the rangetable this is
   * no longer a problem, since then there's only one rtindex namespace.
   *
   * set_plan_references recursively traverses the whole plan tree.
   *
   * The return value is normally the same Plan node passed in, but can be
   * different when the passed-in Plan is a SubqueryScan we decide isn't needed.
   *
   * The flattened rangetable entries are appended to root->glob->finalrtable.
   * Also, rowmarks entries are appended to root->glob->finalrowmarks, and the
   * RT indexes of ModifyTable result relations to root->glob->resultRelations.
   * Plan dependencies are appended to root->glob->relationOids (for relations)
   * and root->glob->invalItems (for everything else).
   *
   * Notice that we modify Plan nodes in-place, but use expression_tree_mutator
   * to process targetlist and qual expressions.	We can assume that the Plan
   * nodes were just built by the planner and are not multiply referenced, but
   * it's not so safe to assume that for expression tree nodes.
   */
  Plan *
  set_plan_references(PlannerInfo *root, Plan *plan)
  {
  	PlannerGlobal *glob = root->glob;
  	int			rtoffset = list_length(glob->finalrtable);
  	ListCell   *lc;
  
  	/*
  	 * Add all the query's RTEs to the flattened rangetable.  The live ones
  	 * will have their rangetable indexes increased by rtoffset.  (Additional
  	 * RTEs, not referenced by the Plan tree, might get added after those.)
  	 */
  	add_rtes_to_flat_rtable(root, false);
  
  	/*
  	 * Adjust RT indexes of PlanRowMarks and add to final rowmarks list
  	 */
  	foreach(lc, root->rowMarks)
  	{
  		PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
  		PlanRowMark *newrc;
  
  		Assert(IsA(rc, PlanRowMark));
  
  		/* flat copy is enough since all fields are scalars */
  		newrc = (PlanRowMark *) palloc(sizeof(PlanRowMark));
  		memcpy(newrc, rc, sizeof(PlanRowMark));
  
  		/* adjust indexes ... but *not* the rowmarkId */
  		newrc->rti += rtoffset;
  		newrc->prti += rtoffset;
  
  		glob->finalrowmarks = lappend(glob->finalrowmarks, newrc);
  	}
  
  	/* Now fix the Plan tree */
  	return set_plan_refs(root, plan, rtoffset);
  }
  
  /*
   * Extract RangeTblEntries from the plan's rangetable, and add to flat rtable
   *
   * This can recurse into subquery plans; "recursing" is true if so.
   */
  static void
  add_rtes_to_flat_rtable(PlannerInfo *root, bool recursing)
  {
  	PlannerGlobal *glob = root->glob;
  	Index		rti;
  	ListCell   *lc;
  
  	/*
  	 * Add the query's own RTEs to the flattened rangetable.
  	 *
  	 * At top level, we must add all RTEs so that their indexes in the
  	 * flattened rangetable match up with their original indexes.  When
  	 * recursing, we only care about extracting relation RTEs.
  	 */
  	foreach(lc, root->parse->rtable)
  	{
  		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
  
  		if (!recursing || rte->rtekind == RTE_RELATION)
  			add_rte_to_flat_rtable(glob, rte);
  	}
  
  	/*
  	 * If there are any dead subqueries, they are not referenced in the Plan
  	 * tree, so we must add RTEs contained in them to the flattened rtable
  	 * separately.	(If we failed to do this, the executor would not perform
  	 * expected permission checks for tables mentioned in such subqueries.)
  	 *
  	 * Note: this pass over the rangetable can't be combined with the previous
  	 * one, because that would mess up the numbering of the live RTEs in the
  	 * flattened rangetable.
  	 */
  	rti = 1;
  	foreach(lc, root->parse->rtable)
  	{
  		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
  
  		/*
  		 * We should ignore inheritance-parent RTEs: their contents have been
  		 * pulled up into our rangetable already.  Also ignore any subquery
  		 * RTEs without matching RelOptInfos, as they likewise have been
  		 * pulled up.
  		 */
  		if (rte->rtekind == RTE_SUBQUERY && !rte->inh)
  		{
  			RelOptInfo *rel = root->simple_rel_array[rti];
  
  			if (rel != NULL)
  			{
  				Assert(rel->relid == rti);		/* sanity check on array */
  
  				/*
  				 * The subquery might never have been planned at all, if it
  				 * was excluded on the basis of self-contradictory constraints
  				 * in our query level.	In this case apply
  				 * flatten_unplanned_rtes.
  				 *
  				 * If it was planned but the plan is dummy, we assume that it
  				 * has been omitted from our plan tree (see
  				 * set_subquery_pathlist), and recurse to pull up its RTEs.
  				 *
  				 * Otherwise, it should be represented by a SubqueryScan node
  				 * somewhere in our plan tree, and we'll pull up its RTEs when
  				 * we process that plan node.
  				 *
  				 * However, if we're recursing, then we should pull up RTEs
  				 * whether the subplan is dummy or not, because we've found
  				 * that some upper query level is treating this one as dummy,
  				 * and so we won't scan this level's plan tree at all.
  				 */
  				if (rel->subplan == NULL)
  					flatten_unplanned_rtes(glob, rte);
  				else if (recursing || is_dummy_plan(rel->subplan))
  				{
  					Assert(rel->subroot != NULL);
  					add_rtes_to_flat_rtable(rel->subroot, true);
  				}
  			}
  		}
  		rti++;
  	}
  }
  
  /*
   * Extract RangeTblEntries from a subquery that was never planned at all
   */
  static void
  flatten_unplanned_rtes(PlannerGlobal *glob, RangeTblEntry *rte)
  {
  	/* Use query_tree_walker to find all RTEs in the parse tree */
  	(void) query_tree_walker(rte->subquery,
  							 flatten_rtes_walker,
  							 (void *) glob,
  							 QTW_EXAMINE_RTES);
  }
  
  static bool
  flatten_rtes_walker(Node *node, PlannerGlobal *glob)
  {
  	if (node == NULL)
  		return false;
  	if (IsA(node, RangeTblEntry))
  	{
  		RangeTblEntry *rte = (RangeTblEntry *) node;
  
  		/* As above, we need only save relation RTEs */
  		if (rte->rtekind == RTE_RELATION)
  			add_rte_to_flat_rtable(glob, rte);
  		return false;
  	}
  	if (IsA(node, Query))
  	{
  		/* Recurse into subselects */
  		return query_tree_walker((Query *) node,
  								 flatten_rtes_walker,
  								 (void *) glob,
  								 QTW_EXAMINE_RTES);
  	}
  	return expression_tree_walker(node, flatten_rtes_walker,
  								  (void *) glob);
  }
  
  /*
   * Add (a copy of) the given RTE to the final rangetable
   *
   * In the flat rangetable, we zero out substructure pointers that are not
   * needed by the executor; this reduces the storage space and copying cost
   * for cached plans.  We keep only the alias and eref Alias fields, which
   * are needed by EXPLAIN, and the selectedCols and modifiedCols bitmaps,
   * which are needed for executor-startup permissions checking and for
   * trigger event checking.
   */
  static void
  add_rte_to_flat_rtable(PlannerGlobal *glob, RangeTblEntry *rte)
  {
  	RangeTblEntry *newrte;
  
  	/* flat copy to duplicate all the scalar fields */
  	newrte = (RangeTblEntry *) palloc(sizeof(RangeTblEntry));
  	memcpy(newrte, rte, sizeof(RangeTblEntry));
  
  	/* zap unneeded sub-structure */
  	newrte->subquery = NULL;
  	newrte->joinaliasvars = NIL;
  	newrte->funcexpr = NULL;
  	newrte->funccoltypes = NIL;
  	newrte->funccoltypmods = NIL;
  	newrte->funccolcollations = NIL;
  	newrte->values_lists = NIL;
  	newrte->values_collations = NIL;
  	newrte->ctecoltypes = NIL;
  	newrte->ctecoltypmods = NIL;
  	newrte->ctecolcollations = NIL;
  
  	glob->finalrtable = lappend(glob->finalrtable, newrte);
  
  	/*
  	 * Check for RT index overflow; it's very unlikely, but if it did happen,
  	 * the executor would get confused by varnos that match the special varno
  	 * values.
  	 */
  	if (IS_SPECIAL_VARNO(list_length(glob->finalrtable)))
  		ereport(ERROR,
  				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
  				 errmsg("too many range table entries")));
  
  	/*
  	 * If it's a plain relation RTE, add the table to relationOids.
  	 *
  	 * We do this even though the RTE might be unreferenced in the plan tree;
  	 * this would correspond to cases such as views that were expanded, child
  	 * tables that were eliminated by constraint exclusion, etc. Schema
  	 * invalidation on such a rel must still force rebuilding of the plan.
  	 *
  	 * Note we don't bother to avoid making duplicate list entries.  We could,
  	 * but it would probably cost more cycles than it would save.
  	 */
  	if (newrte->rtekind == RTE_RELATION)
  		glob->relationOids = lappend_oid(glob->relationOids, newrte->relid);
  }
  
  /*
   * set_plan_refs: recurse through the Plan nodes of a single subquery level
   */
  static Plan *
  set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
  {
  	ListCell   *l;
  
  	if (plan == NULL)
  		return NULL;
  
  	/*
  	 * Plan-type-specific fixes
  	 */
  	switch (nodeTag(plan))
  	{
  		case T_SeqScan:
  			{
  				SeqScan    *splan = (SeqScan *) plan;
  
  				splan->scanrelid += rtoffset;
  				splan->plan.targetlist =
  					fix_scan_list(root, splan->plan.targetlist, rtoffset);
  				splan->plan.qual =
  					fix_scan_list(root, splan->plan.qual, rtoffset);
  			}
  			break;
  		case T_IndexScan:
  			{
  				IndexScan  *splan = (IndexScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  				splan->indexqual =
  					fix_scan_list(root, splan->indexqual, rtoffset);
  				splan->indexqualorig =
  					fix_scan_list(root, splan->indexqualorig, rtoffset);
  				splan->indexorderby =
  					fix_scan_list(root, splan->indexorderby, rtoffset);
  				splan->indexorderbyorig =
  					fix_scan_list(root, splan->indexorderbyorig, rtoffset);
  			}
  			break;
  		case T_IndexOnlyScan:
  			{
  				IndexOnlyScan *splan = (IndexOnlyScan *) plan;
  
  				return set_indexonlyscan_references(root, splan, rtoffset);
  			}
  			break;
  		case T_BitmapIndexScan:
  			{
  				BitmapIndexScan *splan = (BitmapIndexScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				/* no need to fix targetlist and qual */
  				Assert(splan->scan.plan.targetlist == NIL);
  				Assert(splan->scan.plan.qual == NIL);
  				splan->indexqual =
  					fix_scan_list(root, splan->indexqual, rtoffset);
  				splan->indexqualorig =
  					fix_scan_list(root, splan->indexqualorig, rtoffset);
  			}
  			break;
  		case T_BitmapHeapScan:
  			{
  				BitmapHeapScan *splan = (BitmapHeapScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  				splan->bitmapqualorig =
  					fix_scan_list(root, splan->bitmapqualorig, rtoffset);
  			}
  			break;
  		case T_TidScan:
  			{
  				TidScan    *splan = (TidScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  				splan->tidquals =
  					fix_scan_list(root, splan->tidquals, rtoffset);
  			}
  			break;
  		case T_SubqueryScan:
  			/* Needs special treatment, see comments below */
  			return set_subqueryscan_references(root,
  											   (SubqueryScan *) plan,
  											   rtoffset);
  		case T_FunctionScan:
  			{
  				FunctionScan *splan = (FunctionScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  				splan->funcexpr =
  					fix_scan_expr(root, splan->funcexpr, rtoffset);
  			}
  			break;
  		case T_ValuesScan:
  			{
  				ValuesScan *splan = (ValuesScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  				splan->values_lists =
  					fix_scan_list(root, splan->values_lists, rtoffset);
  			}
  			break;
  		case T_CteScan:
  			{
  				CteScan    *splan = (CteScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  			}
  			break;
  		case T_WorkTableScan:
  			{
  				WorkTableScan *splan = (WorkTableScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  			}
  			break;
  		case T_ForeignScan:
  			{
  				ForeignScan *splan = (ForeignScan *) plan;
  
  				splan->scan.scanrelid += rtoffset;
  				splan->scan.plan.targetlist =
  					fix_scan_list(root, splan->scan.plan.targetlist, rtoffset);
  				splan->scan.plan.qual =
  					fix_scan_list(root, splan->scan.plan.qual, rtoffset);
  				splan->fdw_exprs =
  					fix_scan_list(root, splan->fdw_exprs, rtoffset);
  			}
  			break;
  
  		case T_NestLoop:
  		case T_MergeJoin:
  		case T_HashJoin:
  			set_join_references(root, (Join *) plan, rtoffset);
  			break;
  
  		case T_Hash:
  		case T_Material:
  		case T_Sort:
  		case T_Unique:
  		case T_SetOp:
  
  			/*
  			 * These plan types don't actually bother to evaluate their
  			 * targetlists, because they just return their unmodified input
  			 * tuples.	Even though the targetlist won't be used by the
  			 * executor, we fix it up for possible use by EXPLAIN (not to
  			 * mention ease of debugging --- wrong varnos are very confusing).
  			 */
  			set_dummy_tlist_references(plan, rtoffset);
  
  			/*
  			 * Since these plan types don't check quals either, we should not
  			 * find any qual expression attached to them.
  			 */
  			Assert(plan->qual == NIL);
  			break;
  		case T_LockRows:
  			{
  				LockRows   *splan = (LockRows *) plan;
  
  				/*
  				 * Like the plan types above, LockRows doesn't evaluate its
  				 * tlist or quals.	But we have to fix up the RT indexes in
  				 * its rowmarks.
  				 */
  				set_dummy_tlist_references(plan, rtoffset);
  				Assert(splan->plan.qual == NIL);
  
  				foreach(l, splan->rowMarks)
  				{
  					PlanRowMark *rc = (PlanRowMark *) lfirst(l);
  
  					rc->rti += rtoffset;
  					rc->prti += rtoffset;
  				}
  			}
  			break;
  		case T_Limit:
  			{
  				Limit	   *splan = (Limit *) plan;
  
  				/*
  				 * Like the plan types above, Limit doesn't evaluate its tlist
  				 * or quals.  It does have live expressions for limit/offset,
  				 * however; and those cannot contain subplan variable refs, so
  				 * fix_scan_expr works for them.
  				 */
  				set_dummy_tlist_references(plan, rtoffset);
  				Assert(splan->plan.qual == NIL);
  
  				splan->limitOffset =
  					fix_scan_expr(root, splan->limitOffset, rtoffset);
  				splan->limitCount =
  					fix_scan_expr(root, splan->limitCount, rtoffset);
  			}
  			break;
  		case T_Agg:
  		case T_Group:
  			set_upper_references(root, plan, rtoffset);
  			break;
  		case T_WindowAgg:
  			{
  				WindowAgg  *wplan = (WindowAgg *) plan;
  
  				set_upper_references(root, plan, rtoffset);
  
  				/*
  				 * Like Limit node limit/offset expressions, WindowAgg has
  				 * frame offset expressions, which cannot contain subplan
  				 * variable refs, so fix_scan_expr works for them.
  				 */
  				wplan->startOffset =
  					fix_scan_expr(root, wplan->startOffset, rtoffset);
  				wplan->endOffset =
  					fix_scan_expr(root, wplan->endOffset, rtoffset);
  			}
  			break;
  		case T_Result:
  			{
  				Result	   *splan = (Result *) plan;
  
  				/*
  				 * Result may or may not have a subplan; if not, it's more
  				 * like a scan node than an upper node.
  				 */
  				if (splan->plan.lefttree != NULL)
  					set_upper_references(root, plan, rtoffset);
  				else
  				{
  					splan->plan.targetlist =
  						fix_scan_list(root, splan->plan.targetlist, rtoffset);
  					splan->plan.qual =
  						fix_scan_list(root, splan->plan.qual, rtoffset);
  				}
  				/* resconstantqual can't contain any subplan variable refs */
  				splan->resconstantqual =
  					fix_scan_expr(root, splan->resconstantqual, rtoffset);
  			}
  			break;
  		case T_ModifyTable:
  			{
  				ModifyTable *splan = (ModifyTable *) plan;
  
  				Assert(splan->plan.targetlist == NIL);
  				Assert(splan->plan.qual == NIL);
  
  				if (splan->returningLists)
  				{
  					List	   *newRL = NIL;
  					ListCell   *lcrl,
  							   *lcrr,
  							   *lcp;
  
  					/*
  					 * Pass each per-subplan returningList through
  					 * set_returning_clause_references().
  					 */
  					Assert(list_length(splan->returningLists) == list_length(splan->resultRelations));
  					Assert(list_length(splan->returningLists) == list_length(splan->plans));
  					forthree(lcrl, splan->returningLists,
  							 lcrr, splan->resultRelations,
  							 lcp, splan->plans)
  					{
  						List	   *rlist = (List *) lfirst(lcrl);
  						Index		resultrel = lfirst_int(lcrr);
  						Plan	   *subplan = (Plan *) lfirst(lcp);
  
  						rlist = set_returning_clause_references(root,
  																rlist,
  																subplan,
  																resultrel,
  																rtoffset);
  						newRL = lappend(newRL, rlist);
  					}
  					splan->returningLists = newRL;
  
  					/*
  					 * Set up the visible plan targetlist as being the same as
  					 * the first RETURNING list. This is for the use of
  					 * EXPLAIN; the executor won't pay any attention to the
  					 * targetlist.	We postpone this step until here so that
  					 * we don't have to do set_returning_clause_references()
  					 * twice on identical targetlists.
  					 */
  					splan->plan.targetlist = copyObject(linitial(newRL));
  				}
  
  				foreach(l, splan->resultRelations)
  				{
  					lfirst_int(l) += rtoffset;
  				}
  				foreach(l, splan->rowMarks)
  				{
  					PlanRowMark *rc = (PlanRowMark *) lfirst(l);
  
  					rc->rti += rtoffset;
  					rc->prti += rtoffset;
  				}
  				foreach(l, splan->plans)
  				{
  					lfirst(l) = set_plan_refs(root,
  											  (Plan *) lfirst(l),
  											  rtoffset);
  				}
  
  				/*
  				 * Append this ModifyTable node's final result relation RT
  				 * index(es) to the global list for the plan, and set its
  				 * resultRelIndex to reflect their starting position in the
  				 * global list.
  				 */
  				splan->resultRelIndex = list_length(root->glob->resultRelations);
  				root->glob->resultRelations =
  					list_concat(root->glob->resultRelations,
  								list_copy(splan->resultRelations));
  			}
  			break;
  		case T_Append:
  			{
  				Append	   *splan = (Append *) plan;
  
  				/*
  				 * Append, like Sort et al, doesn't actually evaluate its
  				 * targetlist or check quals.
  				 */
  				set_dummy_tlist_references(plan, rtoffset);
  				Assert(splan->plan.qual == NIL);
  				foreach(l, splan->appendplans)
  				{
  					lfirst(l) = set_plan_refs(root,
  											  (Plan *) lfirst(l),
  											  rtoffset);
  				}
  			}
  			break;
  		case T_MergeAppend:
  			{
  				MergeAppend *splan = (MergeAppend *) plan;
  
  				/*
  				 * MergeAppend, like Sort et al, doesn't actually evaluate its
  				 * targetlist or check quals.
  				 */
  				set_dummy_tlist_references(plan, rtoffset);
  				Assert(splan->plan.qual == NIL);
  				foreach(l, splan->mergeplans)
  				{
  					lfirst(l) = set_plan_refs(root,
  											  (Plan *) lfirst(l),
  											  rtoffset);
  				}
  			}
  			break;
  		case T_RecursiveUnion:
  			/* This doesn't evaluate targetlist or check quals either */
  			set_dummy_tlist_references(plan, rtoffset);
  			Assert(plan->qual == NIL);
  			break;
  		case T_BitmapAnd:
  			{
  				BitmapAnd  *splan = (BitmapAnd *) plan;
  
  				/* BitmapAnd works like Append, but has no tlist */
  				Assert(splan->plan.targetlist == NIL);
  				Assert(splan->plan.qual == NIL);
  				foreach(l, splan->bitmapplans)
  				{
  					lfirst(l) = set_plan_refs(root,
  											  (Plan *) lfirst(l),
  											  rtoffset);
  				}
  			}
  			break;
  		case T_BitmapOr:
  			{
  				BitmapOr   *splan = (BitmapOr *) plan;
  
  				/* BitmapOr works like Append, but has no tlist */
  				Assert(splan->plan.targetlist == NIL);
  				Assert(splan->plan.qual == NIL);
  				foreach(l, splan->bitmapplans)
  				{
  					lfirst(l) = set_plan_refs(root,
  											  (Plan *) lfirst(l),
  											  rtoffset);
  				}
  			}
  			break;
  		default:
  			elog(ERROR, "unrecognized node type: %d",
  				 (int) nodeTag(plan));
  			break;
  	}
  
  	/*
  	 * Now recurse into child plans, if any
  	 *
  	 * NOTE: it is essential that we recurse into child plans AFTER we set
  	 * subplan references in this plan's tlist and quals.  If we did the
  	 * reference-adjustments bottom-up, then we would fail to match this
  	 * plan's var nodes against the already-modified nodes of the children.
  	 */
  	plan->lefttree = set_plan_refs(root, plan->lefttree, rtoffset);
  	plan->righttree = set_plan_refs(root, plan->righttree, rtoffset);
  
  	return plan;
  }
  
  /*
   * set_indexonlyscan_references
   *		Do set_plan_references processing on an IndexOnlyScan
   *
   * This is unlike the handling of a plain IndexScan because we have to
   * convert Vars referencing the heap into Vars referencing the index.
   * We can use the fix_upper_expr machinery for that, by working from a
   * targetlist describing the index columns.
   */
  static Plan *
  set_indexonlyscan_references(PlannerInfo *root,
  							 IndexOnlyScan *plan,
  							 int rtoffset)
  {
  	indexed_tlist *index_itlist;
  
  	index_itlist = build_tlist_index(plan->indextlist);
  
  	plan->scan.scanrelid += rtoffset;
  	plan->scan.plan.targetlist = (List *)
  		fix_upper_expr(root,
  					   (Node *) plan->scan.plan.targetlist,
  					   index_itlist,
  					   INDEX_VAR,
  					   rtoffset);
  	plan->scan.plan.qual = (List *)
  		fix_upper_expr(root,
  					   (Node *) plan->scan.plan.qual,
  					   index_itlist,
  					   INDEX_VAR,
  					   rtoffset);
  	/* indexqual is already transformed to reference index columns */
  	plan->indexqual = fix_scan_list(root, plan->indexqual, rtoffset);
  	/* indexorderby is already transformed to reference index columns */
  	plan->indexorderby = fix_scan_list(root, plan->indexorderby, rtoffset);
  	/* indextlist must NOT be transformed to reference index columns */
  	plan->indextlist = fix_scan_list(root, plan->indextlist, rtoffset);
  
  	pfree(index_itlist);
  
  	return (Plan *) plan;
  }
  
  /*
   * set_subqueryscan_references
   *		Do set_plan_references processing on a SubqueryScan
   *
   * We try to strip out the SubqueryScan entirely; if we can't, we have
   * to do the normal processing on it.
   */
  static Plan *
  set_subqueryscan_references(PlannerInfo *root,
  							SubqueryScan *plan,
  							int rtoffset)
  {
  	RelOptInfo *rel;
  	Plan	   *result;
  
  	/* Need to look up the subquery's RelOptInfo, since we need its subroot */
  	rel = find_base_rel(root, plan->scan.scanrelid);
  	Assert(rel->subplan == plan->subplan);
  
  	/* Recursively process the subplan */
  	plan->subplan = set_plan_references(rel->subroot, plan->subplan);
  
  	if (trivial_subqueryscan(plan))
  	{
  		/*
  		 * We can omit the SubqueryScan node and just pull up the subplan.
  		 */
  		ListCell   *lp,
  				   *lc;
  
  		result = plan->subplan;
  
  		/* We have to be sure we don't lose any initplans */
  		result->initPlan = list_concat(plan->scan.plan.initPlan,
  									   result->initPlan);
  
  		/*
  		 * We also have to transfer the SubqueryScan's result-column names
  		 * into the subplan, else columns sent to client will be improperly
  		 * labeled if this is the topmost plan level.  Copy the "source
  		 * column" information too.
  		 */
  		forboth(lp, plan->scan.plan.targetlist, lc, result->targetlist)
  		{
  			TargetEntry *ptle = (TargetEntry *) lfirst(lp);
  			TargetEntry *ctle = (TargetEntry *) lfirst(lc);
  
  			ctle->resname = ptle->resname;
  			ctle->resorigtbl = ptle->resorigtbl;
  			ctle->resorigcol = ptle->resorigcol;
  		}
  	}
  	else
  	{
  		/*
  		 * Keep the SubqueryScan node.	We have to do the processing that
  		 * set_plan_references would otherwise have done on it.  Notice we do
  		 * not do set_upper_references() here, because a SubqueryScan will
  		 * always have been created with correct references to its subplan's
  		 * outputs to begin with.
  		 */
  		plan->scan.scanrelid += rtoffset;
  		plan->scan.plan.targetlist =
  			fix_scan_list(root, plan->scan.plan.targetlist, rtoffset);
  		plan->scan.plan.qual =
  			fix_scan_list(root, plan->scan.plan.qual, rtoffset);
  
  		result = (Plan *) plan;
  	}
  
  	return result;
  }
  
  /*
   * trivial_subqueryscan
   *		Detect whether a SubqueryScan can be deleted from the plan tree.
   *
   * We can delete it if it has no qual to check and the targetlist just
   * regurgitates the output of the child plan.
   */
  static bool
  trivial_subqueryscan(SubqueryScan *plan)
  {
  	int			attrno;
  	ListCell   *lp,
  			   *lc;
  
  	if (plan->scan.plan.qual != NIL)
  		return false;
  
  	if (list_length(plan->scan.plan.targetlist) !=
  		list_length(plan->subplan->targetlist))
  		return false;			/* tlists not same length */
  
  	attrno = 1;
  	forboth(lp, plan->scan.plan.targetlist, lc, plan->subplan->targetlist)
  	{
  		TargetEntry *ptle = (TargetEntry *) lfirst(lp);
  		TargetEntry *ctle = (TargetEntry *) lfirst(lc);
  
  		if (ptle->resjunk != ctle->resjunk)
  			return false;		/* tlist doesn't match junk status */
  
  		/*
  		 * We accept either a Var referencing the corresponding element of the
  		 * subplan tlist, or a Const equaling the subplan element. See
  		 * generate_setop_tlist() for motivation.
  		 */
  		if (ptle->expr && IsA(ptle->expr, Var))
  		{
  			Var		   *var = (Var *) ptle->expr;
  
  			Assert(var->varno == plan->scan.scanrelid);
  			Assert(var->varlevelsup == 0);
  			if (var->varattno != attrno)
  				return false;	/* out of order */
  		}
  		else if (ptle->expr && IsA(ptle->expr, Const))
  		{
  			if (!equal(ptle->expr, ctle->expr))
  				return false;
  		}
  		else
  			return false;
  
  		attrno++;
  	}
  
  	return true;
  }
  
  /*
   * copyVar
   *		Copy a Var node.
   *
   * fix_scan_expr and friends do this enough times that it's worth having
   * a bespoke routine instead of using the generic copyObject() function.
   */
  static inline Var *
  copyVar(Var *var)
  {
  	Var		   *newvar = (Var *) palloc(sizeof(Var));
  
  	*newvar = *var;
  	return newvar;
  }
  
  /*
   * fix_expr_common
   *		Do generic set_plan_references processing on an expression node
   *
   * This is code that is common to all variants of expression-fixing.
   * We must look up operator opcode info for OpExpr and related nodes,
   * add OIDs from regclass Const nodes into root->glob->relationOids, and
   * add catalog TIDs for user-defined functions into root->glob->invalItems.
   *
   * We assume it's okay to update opcode info in-place.  So this could possibly
   * scribble on the planner's input data structures, but it's OK.
   */
  static void
  fix_expr_common(PlannerInfo *root, Node *node)
  {
  	/* We assume callers won't call us on a NULL pointer */
  	if (IsA(node, Aggref))
  	{
  		record_plan_function_dependency(root,
  										((Aggref *) node)->aggfnoid);
  	}
  	else if (IsA(node, WindowFunc))
  	{
  		record_plan_function_dependency(root,
  										((WindowFunc *) node)->winfnoid);
  	}
  	else if (IsA(node, FuncExpr))
  	{
  		record_plan_function_dependency(root,
  										((FuncExpr *) node)->funcid);
  	}
  	else if (IsA(node, OpExpr))
  	{
  		set_opfuncid((OpExpr *) node);
  		record_plan_function_dependency(root,
  										((OpExpr *) node)->opfuncid);
  	}
  	else if (IsA(node, DistinctExpr))
  	{
  		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
  		record_plan_function_dependency(root,
  										((DistinctExpr *) node)->opfuncid);
  	}
  	else if (IsA(node, NullIfExpr))
  	{
  		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
  		record_plan_function_dependency(root,
  										((NullIfExpr *) node)->opfuncid);
  	}
  	else if (IsA(node, ScalarArrayOpExpr))
  	{
  		set_sa_opfuncid((ScalarArrayOpExpr *) node);
  		record_plan_function_dependency(root,
  									 ((ScalarArrayOpExpr *) node)->opfuncid);
  	}
  	else if (IsA(node, ArrayCoerceExpr))
  	{
  		if (OidIsValid(((ArrayCoerceExpr *) node)->elemfuncid))
  			record_plan_function_dependency(root,
  									 ((ArrayCoerceExpr *) node)->elemfuncid);
  	}
  	else if (IsA(node, Const))
  	{
  		Const	   *con = (Const *) node;
  
  		/* Check for regclass reference */
  		if (ISREGCLASSCONST(con))
  			root->glob->relationOids =
  				lappend_oid(root->glob->relationOids,
  							DatumGetObjectId(con->constvalue));
  	}
  }
  
  /*
   * fix_scan_expr
   *		Do set_plan_references processing on a scan-level expression
   *
   * This consists of incrementing all Vars' varnos by rtoffset,
   * looking up operator opcode info for OpExpr and related nodes,
   * and adding OIDs from regclass Const nodes into root->glob->relationOids.
   */
  static Node *
  fix_scan_expr(PlannerInfo *root, Node *node, int rtoffset)
  {
  	fix_scan_expr_context context;
  
  	context.root = root;
  	context.rtoffset = rtoffset;
  
  	if (rtoffset != 0 || root->glob->lastPHId != 0)
  	{
  		return fix_scan_expr_mutator(node, &context);
  	}
  	else
  	{
  		/*
  		 * If rtoffset == 0, we don't need to change any Vars, and if there
  		 * are no placeholders anywhere we won't need to remove them.  Then
  		 * it's OK to just scribble on the input node tree instead of copying
  		 * (since the only change, filling in any unset opfuncid fields, is
  		 * harmless).  This saves just enough cycles to be noticeable on
  		 * trivial queries.
  		 */
  		(void) fix_scan_expr_walker(node, &context);
  		return node;
  	}
  }
  
  static Node *
  fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
  {
  	if (node == NULL)
  		return NULL;
  	if (IsA(node, Var))
  	{
  		Var		   *var = copyVar((Var *) node);
  
  		Assert(var->varlevelsup == 0);
  
  		/*
  		 * We should not see any Vars marked INNER_VAR or OUTER_VAR.  But an
  		 * indexqual expression could contain INDEX_VAR Vars.
  		 */
  		Assert(var->varno != INNER_VAR);
  		Assert(var->varno != OUTER_VAR);
  		if (!IS_SPECIAL_VARNO(var->varno))
  			var->varno += context->rtoffset;
  		if (var->varnoold > 0)
  			var->varnoold += context->rtoffset;
  		return (Node *) var;
  	}
  	if (IsA(node, CurrentOfExpr))
  	{
  		CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);
  
  		Assert(cexpr->cvarno != INNER_VAR);
  		Assert(cexpr->cvarno != OUTER_VAR);
  		if (!IS_SPECIAL_VARNO(cexpr->cvarno))
  			cexpr->cvarno += context->rtoffset;
  		return (Node *) cexpr;
  	}
  	if (IsA(node, PlaceHolderVar))
  	{
  		/* At scan level, we should always just evaluate the contained expr */
  		PlaceHolderVar *phv = (PlaceHolderVar *) node;
  
  		return fix_scan_expr_mutator((Node *) phv->phexpr, context);
  	}
  	fix_expr_common(context->root, node);
  	return expression_tree_mutator(node, fix_scan_expr_mutator,
  								   (void *) context);
  }
  
  static bool
  fix_scan_expr_walker(Node *node, fix_scan_expr_context *context)
  {
  	if (node == NULL)
  		return false;
  	Assert(!IsA(node, PlaceHolderVar));
  	fix_expr_common(context->root, node);
  	return expression_tree_walker(node, fix_scan_expr_walker,
  								  (void *) context);
  }
  
  /*
   * set_join_references
   *	  Modify the target list and quals of a join node to reference its
   *	  subplans, by setting the varnos to OUTER_VAR or INNER_VAR and setting
   *	  attno values to the result domain number of either the corresponding
   *	  outer or inner join tuple item.  Also perform opcode lookup for these
   *	  expressions. and add regclass OIDs to root->glob->relationOids.
   */
  static void
  set_join_references(PlannerInfo *root, Join *join, int rtoffset)
  {
  	Plan	   *outer_plan = join->plan.lefttree;
  	Plan	   *inner_plan = join->plan.righttree;
  	indexed_tlist *outer_itlist;
  	indexed_tlist *inner_itlist;
  
  	outer_itlist = build_tlist_index(outer_plan->targetlist);
  	inner_itlist = build_tlist_index(inner_plan->targetlist);
  
  	/* All join plans have tlist, qual, and joinqual */
  	join->plan.targetlist = fix_join_expr(root,
  										  join->plan.targetlist,
  										  outer_itlist,
  										  inner_itlist,
  										  (Index) 0,
  										  rtoffset);
  	join->plan.qual = fix_join_expr(root,
  									join->plan.qual,
  									outer_itlist,
  									inner_itlist,
  									(Index) 0,
  									rtoffset);
  	join->joinqual = fix_join_expr(root,
  								   join->joinqual,
  								   outer_itlist,
  								   inner_itlist,
  								   (Index) 0,
  								   rtoffset);
  
  	/* Now do join-type-specific stuff */
  	if (IsA(join, NestLoop))
  	{
  		NestLoop   *nl = (NestLoop *) join;
  		ListCell   *lc;
  
  		foreach(lc, nl->nestParams)
  		{
  			NestLoopParam *nlp = (NestLoopParam *) lfirst(lc);
  
  			nlp->paramval = (Var *) fix_upper_expr(root,
  												   (Node *) nlp->paramval,
  												   outer_itlist,
  												   OUTER_VAR,
  												   rtoffset);
  			/* Check we replaced any PlaceHolderVar with simple Var */
  			if (!(IsA(nlp->paramval, Var) &&
  				  nlp->paramval->varno == OUTER_VAR))
  				elog(ERROR, "NestLoopParam was not reduced to a simple Var");
  		}
  	}
  	else if (IsA(join, MergeJoin))
  	{
  		MergeJoin  *mj = (MergeJoin *) join;
  
  		mj->mergeclauses = fix_join_expr(root,
  										 mj->mergeclauses,
  										 outer_itlist,
  										 inner_itlist,
  										 (Index) 0,
  										 rtoffset);
  	}
  	else if (IsA(join, HashJoin))
  	{
  		HashJoin   *hj = (HashJoin *) join;
  
  		hj->hashclauses = fix_join_expr(root,
  										hj->hashclauses,
  										outer_itlist,
  										inner_itlist,
  										(Index) 0,
  										rtoffset);
  	}
  
  	pfree(outer_itlist);
  	pfree(inner_itlist);
  }
  
  /*
   * set_upper_references
   *	  Update the targetlist and quals of an upper-level plan node
   *	  to refer to the tuples returned by its lefttree subplan.
   *	  Also perform opcode lookup for these expressions, and
   *	  add regclass OIDs to root->glob->relationOids.
   *
   * This is used for single-input plan types like Agg, Group, Result.
   *
   * In most cases, we have to match up individual Vars in the tlist and
   * qual expressions with elements of the subplan's tlist (which was
   * generated by flatten_tlist() from these selfsame expressions, so it
   * should have all the required variables).  There is an important exception,
   * however: GROUP BY and ORDER BY expressions will have been pushed into the
   * subplan tlist unflattened.  If these values are also needed in the output
   * then we want to reference the subplan tlist element rather than recomputing
   * the expression.
   */
  static void
  set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
  {
  	Plan	   *subplan = plan->lefttree;
  	indexed_tlist *subplan_itlist;
  	List	   *output_targetlist;
  	ListCell   *l;
  
  	subplan_itlist = build_tlist_index(subplan->targetlist);
  
  	output_targetlist = NIL;
  	foreach(l, plan->targetlist)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(l);
  		Node	   *newexpr;
  
  		/* If it's a non-Var sort/group item, first try to match by sortref */
  		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
  		{
  			newexpr = (Node *)
  				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
  													  tle->ressortgroupref,
  													  subplan_itlist,
  													  OUTER_VAR);
  			if (!newexpr)
  				newexpr = fix_upper_expr(root,
  										 (Node *) tle->expr,
  										 subplan_itlist,
  										 OUTER_VAR,
  										 rtoffset);
  		}
  		else
  			newexpr = fix_upper_expr(root,
  									 (Node *) tle->expr,
  									 subplan_itlist,
  									 OUTER_VAR,
  									 rtoffset);
  		tle = flatCopyTargetEntry(tle);
  		tle->expr = (Expr *) newexpr;
  		output_targetlist = lappend(output_targetlist, tle);
  	}
  	plan->targetlist = output_targetlist;
  
  	plan->qual = (List *)
  		fix_upper_expr(root,
  					   (Node *) plan->qual,
  					   subplan_itlist,
  					   OUTER_VAR,
  					   rtoffset);
  
  	pfree(subplan_itlist);
  }
  
  /*
   * set_dummy_tlist_references
   *	  Replace the targetlist of an upper-level plan node with a simple
   *	  list of OUTER_VAR references to its child.
   *
   * This is used for plan types like Sort and Append that don't evaluate
   * their targetlists.  Although the executor doesn't care at all what's in
   * the tlist, EXPLAIN needs it to be realistic.
   *
   * Note: we could almost use set_upper_references() here, but it fails for
   * Append for lack of a lefttree subplan.  Single-purpose code is faster
   * anyway.
   */
  static void
  set_dummy_tlist_references(Plan *plan, int rtoffset)
  {
  	List	   *output_targetlist;
  	ListCell   *l;
  
  	output_targetlist = NIL;
  	foreach(l, plan->targetlist)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(l);
  		Var		   *oldvar = (Var *) tle->expr;
  		Var		   *newvar;
  
  		newvar = makeVar(OUTER_VAR,
  						 tle->resno,
  						 exprType((Node *) oldvar),
  						 exprTypmod((Node *) oldvar),
  						 exprCollation((Node *) oldvar),
  						 0);
  		if (IsA(oldvar, Var))
  		{
  			newvar->varnoold = oldvar->varno + rtoffset;
  			newvar->varoattno = oldvar->varattno;
  		}
  		else
  		{
  			newvar->varnoold = 0;		/* wasn't ever a plain Var */
  			newvar->varoattno = 0;
  		}
  
  		tle = flatCopyTargetEntry(tle);
  		tle->expr = (Expr *) newvar;
  		output_targetlist = lappend(output_targetlist, tle);
  	}
  	plan->targetlist = output_targetlist;
  
  	/* We don't touch plan->qual here */
  }
  
  
  /*
   * build_tlist_index --- build an index data structure for a child tlist
   *
   * In most cases, subplan tlists will be "flat" tlists with only Vars,
   * so we try to optimize that case by extracting information about Vars
   * in advance.	Matching a parent tlist to a child is still an O(N^2)
   * operation, but at least with a much smaller constant factor than plain
   * tlist_member() searches.
   *
   * The result of this function is an indexed_tlist struct to pass to
   * search_indexed_tlist_for_var() or search_indexed_tlist_for_non_var().
   * When done, the indexed_tlist may be freed with a single pfree().
   */
  static indexed_tlist *
  build_tlist_index(List *tlist)
  {
  	indexed_tlist *itlist;
  	tlist_vinfo *vinfo;
  	ListCell   *l;
  
  	/* Create data structure with enough slots for all tlist entries */
  	itlist = (indexed_tlist *)
  		palloc(offsetof(indexed_tlist, vars) +
  			   list_length(tlist) * sizeof(tlist_vinfo));
  
  	itlist->tlist = tlist;
  	itlist->has_ph_vars = false;
  	itlist->has_non_vars = false;
  
  	/* Find the Vars and fill in the index array */
  	vinfo = itlist->vars;
  	foreach(l, tlist)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(l);
  
  		if (tle->expr && IsA(tle->expr, Var))
  		{
  			Var		   *var = (Var *) tle->expr;
  
  			vinfo->varno = var->varno;
  			vinfo->varattno = var->varattno;
  			vinfo->resno = tle->resno;
  			vinfo++;
  		}
  		else if (tle->expr && IsA(tle->expr, PlaceHolderVar))
  			itlist->has_ph_vars = true;
  		else
  			itlist->has_non_vars = true;
  	}
  
  	itlist->num_vars = (vinfo - itlist->vars);
  
  	return itlist;
  }
  
  /*
   * build_tlist_index_other_vars --- build a restricted tlist index
   *
   * This is like build_tlist_index, but we only index tlist entries that
   * are Vars belonging to some rel other than the one specified.  We will set
   * has_ph_vars (allowing PlaceHolderVars to be matched), but not has_non_vars
   * (so nothing other than Vars and PlaceHolderVars can be matched).
   */
  static indexed_tlist *
  build_tlist_index_other_vars(List *tlist, Index ignore_rel)
  {
  	indexed_tlist *itlist;
  	tlist_vinfo *vinfo;
  	ListCell   *l;
  
  	/* Create data structure with enough slots for all tlist entries */
  	itlist = (indexed_tlist *)
  		palloc(offsetof(indexed_tlist, vars) +
  			   list_length(tlist) * sizeof(tlist_vinfo));
  
  	itlist->tlist = tlist;
  	itlist->has_ph_vars = false;
  	itlist->has_non_vars = false;
  
  	/* Find the desired Vars and fill in the index array */
  	vinfo = itlist->vars;
  	foreach(l, tlist)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(l);
  
  		if (tle->expr && IsA(tle->expr, Var))
  		{
  			Var		   *var = (Var *) tle->expr;
  
  			if (var->varno != ignore_rel)
  			{
  				vinfo->varno = var->varno;
  				vinfo->varattno = var->varattno;
  				vinfo->resno = tle->resno;
  				vinfo++;
  			}
  		}
  		else if (tle->expr && IsA(tle->expr, PlaceHolderVar))
  			itlist->has_ph_vars = true;
  	}
  
  	itlist->num_vars = (vinfo - itlist->vars);
  
  	return itlist;
  }
  
  /*
   * search_indexed_tlist_for_var --- find a Var in an indexed tlist
   *
   * If a match is found, return a copy of the given Var with suitably
   * modified varno/varattno (to wit, newvarno and the resno of the TLE entry).
   * Also ensure that varnoold is incremented by rtoffset.
   * If no match, return NULL.
   */
  static Var *
  search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist,
  							 Index newvarno, int rtoffset)
  {
  	Index		varno = var->varno;
  	AttrNumber	varattno = var->varattno;
  	tlist_vinfo *vinfo;
  	int			i;
  
  	vinfo = itlist->vars;
  	i = itlist->num_vars;
  	while (i-- > 0)
  	{
  		if (vinfo->varno == varno && vinfo->varattno == varattno)
  		{
  			/* Found a match */
  			Var		   *newvar = copyVar(var);
  
  			newvar->varno = newvarno;
  			newvar->varattno = vinfo->resno;
  			if (newvar->varnoold > 0)
  				newvar->varnoold += rtoffset;
  			return newvar;
  		}
  		vinfo++;
  	}
  	return NULL;				/* no match */
  }
  
  /*
   * search_indexed_tlist_for_non_var --- find a non-Var in an indexed tlist
   *
   * If a match is found, return a Var constructed to reference the tlist item.
   * If no match, return NULL.
   *
   * NOTE: it is a waste of time to call this unless itlist->has_ph_vars or
   * itlist->has_non_vars
   */
  static Var *
  search_indexed_tlist_for_non_var(Node *node,
  								 indexed_tlist *itlist, Index newvarno)
  {
  	TargetEntry *tle;
  
  	tle = tlist_member(node, itlist->tlist);
  	if (tle)
  	{
  		/* Found a matching subplan output expression */
  		Var		   *newvar;
  
  		newvar = makeVarFromTargetEntry(newvarno, tle);
  		newvar->varnoold = 0;	/* wasn't ever a plain Var */
  		newvar->varoattno = 0;
  		return newvar;
  	}
  	return NULL;				/* no match */
  }
  
  /*
   * search_indexed_tlist_for_sortgroupref --- find a sort/group expression
   *		(which is assumed not to be just a Var)
   *
   * If a match is found, return a Var constructed to reference the tlist item.
   * If no match, return NULL.
   *
   * This is needed to ensure that we select the right subplan TLE in cases
   * where there are multiple textually-equal()-but-volatile sort expressions.
   * And it's also faster than search_indexed_tlist_for_non_var.
   */
  static Var *
  search_indexed_tlist_for_sortgroupref(Node *node,
  									  Index sortgroupref,
  									  indexed_tlist *itlist,
  									  Index newvarno)
  {
  	ListCell   *lc;
  
  	foreach(lc, itlist->tlist)
  	{
  		TargetEntry *tle = (TargetEntry *) lfirst(lc);
  
  		/* The equal() check should be redundant, but let's be paranoid */
  		if (tle->ressortgroupref == sortgroupref &&
  			equal(node, tle->expr))
  		{
  			/* Found a matching subplan output expression */
  			Var		   *newvar;
  
  			newvar = makeVarFromTargetEntry(newvarno, tle);
  			newvar->varnoold = 0;		/* wasn't ever a plain Var */
  			newvar->varoattno = 0;
  			return newvar;
  		}
  	}
  	return NULL;				/* no match */
  }
  
  /*
   * fix_join_expr
   *	   Create a new set of targetlist entries or join qual clauses by
   *	   changing the varno/varattno values of variables in the clauses
   *	   to reference target list values from the outer and inner join
   *	   relation target lists.  Also perform opcode lookup and add
   *	   regclass OIDs to root->glob->relationOids.
   *
   * This is used in two different scenarios: a normal join clause, where all
   * the Vars in the clause *must* be replaced by OUTER_VAR or INNER_VAR
   * references; and a RETURNING clause, which may contain both Vars of the
   * target relation and Vars of other relations.  In the latter case we want
   * to replace the other-relation Vars by OUTER_VAR references, while leaving
   * target Vars alone.
   *
   * For a normal join, acceptable_rel should be zero so that any failure to
   * match a Var will be reported as an error.  For the RETURNING case, pass
   * inner_itlist = NULL and acceptable_rel = the ID of the target relation.
   *
   * 'clauses' is the targetlist or list of join clauses
   * 'outer_itlist' is the indexed target list of the outer join relation
   * 'inner_itlist' is the indexed target list of the inner join relation,
   *		or NULL
   * 'acceptable_rel' is either zero or the rangetable index of a relation
   *		whose Vars may appear in the clause without provoking an error
   * 'rtoffset': how much to increment varnoold by
   *
   * Returns the new expression tree.  The original clause structure is
   * not modified.
   */
  static List *
  fix_join_expr(PlannerInfo *root,
  			  List *clauses,
  			  indexed_tlist *outer_itlist,
  			  indexed_tlist *inner_itlist,
  			  Index acceptable_rel,
  			  int rtoffset)
  {
  	fix_join_expr_context context;
  
  	context.root = root;
  	context.outer_itlist = outer_itlist;
  	context.inner_itlist = inner_itlist;
  	context.acceptable_rel = acceptable_rel;
  	context.rtoffset = rtoffset;
  	return (List *) fix_join_expr_mutator((Node *) clauses, &context);
  }
  
  static Node *
  fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
  {
  	Var		   *newvar;
  
  	if (node == NULL)
  		return NULL;
  	if (IsA(node, Var))
  	{
  		Var		   *var = (Var *) node;
  
  		/* First look for the var in the input tlists */
  		newvar = search_indexed_tlist_for_var(var,
  											  context->outer_itlist,
  											  OUTER_VAR,
  											  context->rtoffset);
  		if (newvar)
  			return (Node *) newvar;
  		if (context->inner_itlist)
  		{
  			newvar = search_indexed_tlist_for_var(var,
  												  context->inner_itlist,
  												  INNER_VAR,
  												  context->rtoffset);
  			if (newvar)
  				return (Node *) newvar;
  		}
  
  		/* If it's for acceptable_rel, adjust and return it */
  		if (var->varno == context->acceptable_rel)
  		{
  			var = copyVar(var);
  			var->varno += context->rtoffset;
  			if (var->varnoold > 0)
  				var->varnoold += context->rtoffset;
  			return (Node *) var;
  		}
  
  		/* No referent found for Var */
  		elog(ERROR, "variable not found in subplan target lists");
  	}
  	if (IsA(node, PlaceHolderVar))
  	{
  		PlaceHolderVar *phv = (PlaceHolderVar *) node;
  
  		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
  		if (context->outer_itlist->has_ph_vars)
  		{
  			newvar = search_indexed_tlist_for_non_var((Node *) phv,
  													  context->outer_itlist,
  													  OUTER_VAR);
  			if (newvar)
  				return (Node *) newvar;
  		}
  		if (context->inner_itlist && context->inner_itlist->has_ph_vars)
  		{
  			newvar = search_indexed_tlist_for_non_var((Node *) phv,
  													  context->inner_itlist,
  													  INNER_VAR);
  			if (newvar)
  				return (Node *) newvar;
  		}
  
  		/* If not supplied by input plans, evaluate the contained expr */
  		return fix_join_expr_mutator((Node *) phv->phexpr, context);
  	}
  	/* Try matching more complex expressions too, if tlists have any */
  	if (context->outer_itlist->has_non_vars)
  	{
  		newvar = search_indexed_tlist_for_non_var(node,
  												  context->outer_itlist,
  												  OUTER_VAR);
  		if (newvar)
  			return (Node *) newvar;
  	}
  	if (context->inner_itlist && context->inner_itlist->has_non_vars)
  	{
  		newvar = search_indexed_tlist_for_non_var(node,
  												  context->inner_itlist,
  												  INNER_VAR);
  		if (newvar)
  			return (Node *) newvar;
  	}
  	fix_expr_common(context->root, node);
  	return expression_tree_mutator(node,
  								   fix_join_expr_mutator,
  								   (void *) context);
  }
  
  /*
   * fix_upper_expr
   *		Modifies an expression tree so that all Var nodes reference outputs
   *		of a subplan.  Also performs opcode lookup, and adds regclass OIDs to
   *		root->glob->relationOids.
   *
   * This is used to fix up target and qual expressions of non-join upper-level
   * plan nodes, as well as index-only scan nodes.
   *
   * An error is raised if no matching var can be found in the subplan tlist
   * --- so this routine should only be applied to nodes whose subplans'
   * targetlists were generated via flatten_tlist() or some such method.
   *
   * If itlist->has_non_vars is true, then we try to match whole subexpressions
   * against elements of the subplan tlist, so that we can avoid recomputing
   * expressions that were already computed by the subplan.  (This is relatively
   * expensive, so we don't want to try it in the common case where the
   * subplan tlist is just a flattened list of Vars.)
   *
   * 'node': the tree to be fixed (a target item or qual)
   * 'subplan_itlist': indexed target list for subplan (or index)
   * 'newvarno': varno to use for Vars referencing tlist elements
   * 'rtoffset': how much to increment varnoold by
   *
   * The resulting tree is a copy of the original in which all Var nodes have
   * varno = newvarno, varattno = resno of corresponding targetlist element.
   * The original tree is not modified.
   */
  static Node *
  fix_upper_expr(PlannerInfo *root,
  			   Node *node,
  			   indexed_tlist *subplan_itlist,
  			   Index newvarno,
  			   int rtoffset)
  {
  	fix_upper_expr_context context;
  
  	context.root = root;
  	context.subplan_itlist = subplan_itlist;
  	context.newvarno = newvarno;
  	context.rtoffset = rtoffset;
  	return fix_upper_expr_mutator(node, &context);
  }
  
  static Node *
  fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
  {
  	Var		   *newvar;
  
  	if (node == NULL)
  		return NULL;
  	if (IsA(node, Var))
  	{
  		Var		   *var = (Var *) node;
  
  		newvar = search_indexed_tlist_for_var(var,
  											  context->subplan_itlist,
  											  context->newvarno,
  											  context->rtoffset);
  		if (!newvar)
  			elog(ERROR, "variable not found in subplan target list");
  		return (Node *) newvar;
  	}
  	if (IsA(node, PlaceHolderVar))
  	{
  		PlaceHolderVar *phv = (PlaceHolderVar *) node;
  
  		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
  		if (context->subplan_itlist->has_ph_vars)
  		{
  			newvar = search_indexed_tlist_for_non_var((Node *) phv,
  													  context->subplan_itlist,
  													  context->newvarno);
  			if (newvar)
  				return (Node *) newvar;
  		}
  		/* If not supplied by input plan, evaluate the contained expr */
  		return fix_upper_expr_mutator((Node *) phv->phexpr, context);
  	}
  	/* Try matching more complex expressions too, if tlist has any */
  	if (context->subplan_itlist->has_non_vars)
  	{
  		newvar = search_indexed_tlist_for_non_var(node,
  												  context->subplan_itlist,
  												  context->newvarno);
  		if (newvar)
  			return (Node *) newvar;
  	}
  	fix_expr_common(context->root, node);
  	return expression_tree_mutator(node,
  								   fix_upper_expr_mutator,
  								   (void *) context);
  }
  
  /*
   * set_returning_clause_references
   *		Perform setrefs.c's work on a RETURNING targetlist
   *
   * If the query involves more than just the result table, we have to
   * adjust any Vars that refer to other tables to reference junk tlist
   * entries in the top subplan's targetlist.  Vars referencing the result
   * table should be left alone, however (the executor will evaluate them
   * using the actual heap tuple, after firing triggers if any).	In the
   * adjusted RETURNING list, result-table Vars will have their original
   * varno (plus rtoffset), but Vars for other rels will have varno OUTER_VAR.
   *
   * We also must perform opcode lookup and add regclass OIDs to
   * root->glob->relationOids.
   *
   * 'rlist': the RETURNING targetlist to be fixed
   * 'topplan': the top subplan node that will be just below the ModifyTable
   *		node (note it's not yet passed through set_plan_refs)
   * 'resultRelation': RT index of the associated result relation
   * 'rtoffset': how much to increment varnos by
   *
   * Note: the given 'root' is for the parent query level, not the 'topplan'.
   * This does not matter currently since we only access the dependency-item
   * lists in root->glob, but it would need some hacking if we wanted a root
   * that actually matches the subplan.
   *
   * Note: resultRelation is not yet adjusted by rtoffset.
   */
  static List *
  set_returning_clause_references(PlannerInfo *root,
  								List *rlist,
  								Plan *topplan,
  								Index resultRelation,
  								int rtoffset)
  {
  	indexed_tlist *itlist;
  
  	/*
  	 * We can perform the desired Var fixup by abusing the fix_join_expr
  	 * machinery that formerly handled inner indexscan fixup.  We search the
  	 * top plan's targetlist for Vars of non-result relations, and use
  	 * fix_join_expr to convert RETURNING Vars into references to those tlist
  	 * entries, while leaving result-rel Vars as-is.
  	 *
  	 * PlaceHolderVars will also be sought in the targetlist, but no
  	 * more-complex expressions will be.  Note that it is not possible for a
  	 * PlaceHolderVar to refer to the result relation, since the result is
  	 * never below an outer join.  If that case could happen, we'd have to be
  	 * prepared to pick apart the PlaceHolderVar and evaluate its contained
  	 * expression instead.
  	 */
  	itlist = build_tlist_index_other_vars(topplan->targetlist, resultRelation);
  
  	rlist = fix_join_expr(root,
  						  rlist,
  						  itlist,
  						  NULL,
  						  resultRelation,
  						  rtoffset);
  
  	pfree(itlist);
  
  	return rlist;
  }
  
  /*****************************************************************************
   *					OPERATOR REGPROC LOOKUP
   *****************************************************************************/
  
  /*
   * fix_opfuncids
   *	  Calculate opfuncid field from opno for each OpExpr node in given tree.
   *	  The given tree can be anything expression_tree_walker handles.
   *
   * The argument is modified in-place.  (This is OK since we'd want the
   * same change for any node, even if it gets visited more than once due to
   * shared structure.)
   */
  void
  fix_opfuncids(Node *node)
  {
  	/* This tree walk requires no special setup, so away we go... */
  	fix_opfuncids_walker(node, NULL);
  }
  
  static bool
  fix_opfuncids_walker(Node *node, void *context)
  {
  	if (node == NULL)
  		return false;
  	if (IsA(node, OpExpr))
  		set_opfuncid((OpExpr *) node);
  	else if (IsA(node, DistinctExpr))
  		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
  	else if (IsA(node, NullIfExpr))
  		set_opfuncid((OpExpr *) node);	/* rely on struct equivalence */
  	else if (IsA(node, ScalarArrayOpExpr))
  		set_sa_opfuncid((ScalarArrayOpExpr *) node);
  	return expression_tree_walker(node, fix_opfuncids_walker, context);
  }
  
  /*
   * set_opfuncid
   *		Set the opfuncid (procedure OID) in an OpExpr node,
   *		if it hasn't been set already.
   *
   * Because of struct equivalence, this can also be used for
   * DistinctExpr and NullIfExpr nodes.
   */
  void
  set_opfuncid(OpExpr *opexpr)
  {
  	if (opexpr->opfuncid == InvalidOid)
  		opexpr->opfuncid = get_opcode(opexpr->opno);
  }
  
  /*
   * set_sa_opfuncid
   *		As above, for ScalarArrayOpExpr nodes.
   */
  void
  set_sa_opfuncid(ScalarArrayOpExpr *opexpr)
  {
  	if (opexpr->opfuncid == InvalidOid)
  		opexpr->opfuncid = get_opcode(opexpr->opno);
  }
  
  /*****************************************************************************
   *					QUERY DEPENDENCY MANAGEMENT
   *****************************************************************************/
  
  /*
   * record_plan_function_dependency
   *		Mark the current plan as depending on a particular function.
   *
   * This is exported so that the function-inlining code can record a
   * dependency on a function that it's removed from the plan tree.
   */
  void
  record_plan_function_dependency(PlannerInfo *root, Oid funcid)
  {
  	/*
  	 * For performance reasons, we don't bother to track built-in functions;
  	 * we just assume they'll never change (or at least not in ways that'd
  	 * invalidate plans using them).  For this purpose we can consider a
  	 * built-in function to be one with OID less than FirstBootstrapObjectId.
  	 * Note that the OID generator guarantees never to generate such an OID
  	 * after startup, even at OID wraparound.
  	 */
  	if (funcid >= (Oid) FirstBootstrapObjectId)
  	{
  		PlanInvalItem *inval_item = makeNode(PlanInvalItem);
  
  		/*
  		 * It would work to use any syscache on pg_proc, but the easiest is
  		 * PROCOID since we already have the function's OID at hand.  Note
  		 * that plancache.c knows we use PROCOID.
  		 */
  		inval_item->cacheId = PROCOID;
  		inval_item->hashValue = GetSysCacheHashValue1(PROCOID,
  												   ObjectIdGetDatum(funcid));
  
  		root->glob->invalItems = lappend(root->glob->invalItems, inval_item);
  	}
  }
  
  /*
   * extract_query_dependencies
   *		Given a not-yet-planned query or queries (i.e. a Query node or list
   *		of Query nodes), extract dependencies just as set_plan_references
   *		would do.
   *
   * This is needed by plancache.c to handle invalidation of cached unplanned
   * queries.
   */
  void
  extract_query_dependencies(Node *query,
  						   List **relationOids,
  						   List **invalItems)
  {
  	PlannerGlobal glob;
  	PlannerInfo root;
  
  	/* Make up dummy planner state so we can use this module's machinery */
  	MemSet(&glob, 0, sizeof(glob));
  	glob.type = T_PlannerGlobal;
  	glob.relationOids = NIL;
  	glob.invalItems = NIL;
  
  	MemSet(&root, 0, sizeof(root));
  	root.type = T_PlannerInfo;
  	root.glob = &glob;
  
  	(void) extract_query_dependencies_walker(query, &root);
  
  	*relationOids = glob.relationOids;
  	*invalItems = glob.invalItems;
  }
  
  static bool
  extract_query_dependencies_walker(Node *node, PlannerInfo *context)
  {
  	if (node == NULL)
  		return false;
  	Assert(!IsA(node, PlaceHolderVar));
  	/* Extract function dependencies and check for regclass Consts */
  	fix_expr_common(context, node);
  	if (IsA(node, Query))
  	{
  		Query	   *query = (Query *) node;
  		ListCell   *lc;
  
  		if (query->commandType == CMD_UTILITY)
  		{
  			/*
  			 * Ignore utility statements, except those (such as EXPLAIN) that
  			 * contain a parsed-but-not-planned query.
  			 */
  			query = UtilityContainsQuery(query->utilityStmt);
  			if (query == NULL)
  				return false;
  		}
  
  		/* Collect relation OIDs in this Query's rtable */
  		foreach(lc, query->rtable)
  		{
  			RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
  
  			if (rte->rtekind == RTE_RELATION)
  				context->glob->relationOids =
  					lappend_oid(context->glob->relationOids, rte->relid);
  		}
  
  		/* And recurse into the query's subexpressions */
  		return query_tree_walker(query, extract_query_dependencies_walker,
  								 (void *) context, 0);
  	}
  	return expression_tree_walker(node, extract_query_dependencies_walker,
  								  (void *) context);
  }
  