Adding upstream version 15.5.upstream/15.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1536 insertions, 0 deletions

diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
new file mode 100644
index 0000000..8c8067b
--- /dev/null
+++ b/src/backend/rewrite/rewriteManip.c
@@ -0,0 +1,1536 @@
+/*-------------------------------------------------------------------------
+ *
+ * rewriteManip.c
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/rewrite/rewriteManip.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "catalog/pg_type.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "nodes/pathnodes.h"
+#include "nodes/plannodes.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_relation.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteManip.h"
+
+
+typedef struct
+{
+	int			sublevels_up;
+} contain_aggs_of_level_context;
+
+typedef struct
+{
+	int			agg_location;
+	int			sublevels_up;
+} locate_agg_of_level_context;
+
+typedef struct
+{
+	int			win_location;
+} locate_windowfunc_context;
+
+static bool contain_aggs_of_level_walker(Node *node,
+										 contain_aggs_of_level_context *context);
+static bool locate_agg_of_level_walker(Node *node,
+									   locate_agg_of_level_context *context);
+static bool contain_windowfuncs_walker(Node *node, void *context);
+static bool locate_windowfunc_walker(Node *node,
+									 locate_windowfunc_context *context);
+static bool checkExprHasSubLink_walker(Node *node, void *context);
+static Relids offset_relid_set(Relids relids, int offset);
+static Relids adjust_relid_set(Relids relids, int oldrelid, int newrelid);
+
+
+/*
+ * contain_aggs_of_level -
+ *	Check if an expression contains an aggregate function call of a
+ *	specified query level.
+ *
+ * The objective of this routine is to detect whether there are aggregates
+ * belonging to the given query level.  Aggregates belonging to subqueries
+ * or outer queries do NOT cause a true result.  We must recurse into
+ * subqueries to detect outer-reference aggregates that logically belong to
+ * the specified query level.
+ */
+bool
+contain_aggs_of_level(Node *node, int levelsup)
+{
+	contain_aggs_of_level_context context;
+
+	context.sublevels_up = levelsup;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	return query_or_expression_tree_walker(node,
+										   contain_aggs_of_level_walker,
+										   (void *) &context,
+										   0);
+}
+
+static bool
+contain_aggs_of_level_walker(Node *node,
+							 contain_aggs_of_level_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		if (((Aggref *) node)->agglevelsup == context->sublevels_up)
+			return true;		/* abort the tree traversal and return true */
+		/* else fall through to examine argument */
+	}
+	if (IsA(node, GroupingFunc))
+	{
+		if (((GroupingFunc *) node)->agglevelsup == context->sublevels_up)
+			return true;
+		/* else fall through to examine argument */
+	}
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node,
+								   contain_aggs_of_level_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	return expression_tree_walker(node, contain_aggs_of_level_walker,
+								  (void *) context);
+}
+
+/*
+ * locate_agg_of_level -
+ *	  Find the parse location of any aggregate of the specified query level.
+ *
+ * Returns -1 if no such agg is in the querytree, or if they all have
+ * unknown parse location.  (The former case is probably caller error,
+ * but we don't bother to distinguish it from the latter case.)
+ *
+ * Note: it might seem appropriate to merge this functionality into
+ * contain_aggs_of_level, but that would complicate that function's API.
+ * Currently, the only uses of this function are for error reporting,
+ * and so shaving cycles probably isn't very important.
+ */
+int
+locate_agg_of_level(Node *node, int levelsup)
+{
+	locate_agg_of_level_context context;
+
+	context.agg_location = -1;	/* in case we find nothing */
+	context.sublevels_up = levelsup;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	(void) query_or_expression_tree_walker(node,
+										   locate_agg_of_level_walker,
+										   (void *) &context,
+										   0);
+
+	return context.agg_location;
+}
+
+static bool
+locate_agg_of_level_walker(Node *node,
+						   locate_agg_of_level_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		if (((Aggref *) node)->agglevelsup == context->sublevels_up &&
+			((Aggref *) node)->location >= 0)
+		{
+			context->agg_location = ((Aggref *) node)->location;
+			return true;		/* abort the tree traversal and return true */
+		}
+		/* else fall through to examine argument */
+	}
+	if (IsA(node, GroupingFunc))
+	{
+		if (((GroupingFunc *) node)->agglevelsup == context->sublevels_up &&
+			((GroupingFunc *) node)->location >= 0)
+		{
+			context->agg_location = ((GroupingFunc *) node)->location;
+			return true;		/* abort the tree traversal and return true */
+		}
+	}
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node,
+								   locate_agg_of_level_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	return expression_tree_walker(node, locate_agg_of_level_walker,
+								  (void *) context);
+}
+
+/*
+ * contain_windowfuncs -
+ *	Check if an expression contains a window function call of the
+ *	current query level.
+ */
+bool
+contain_windowfuncs(Node *node)
+{
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	return query_or_expression_tree_walker(node,
+										   contain_windowfuncs_walker,
+										   NULL,
+										   0);
+}
+
+static bool
+contain_windowfuncs_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, WindowFunc))
+		return true;			/* abort the tree traversal and return true */
+	/* Mustn't recurse into subselects */
+	return expression_tree_walker(node, contain_windowfuncs_walker,
+								  (void *) context);
+}
+
+/*
+ * locate_windowfunc -
+ *	  Find the parse location of any windowfunc of the current query level.
+ *
+ * Returns -1 if no such windowfunc is in the querytree, or if they all have
+ * unknown parse location.  (The former case is probably caller error,
+ * but we don't bother to distinguish it from the latter case.)
+ *
+ * Note: it might seem appropriate to merge this functionality into
+ * contain_windowfuncs, but that would complicate that function's API.
+ * Currently, the only uses of this function are for error reporting,
+ * and so shaving cycles probably isn't very important.
+ */
+int
+locate_windowfunc(Node *node)
+{
+	locate_windowfunc_context context;
+
+	context.win_location = -1;	/* in case we find nothing */
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	(void) query_or_expression_tree_walker(node,
+										   locate_windowfunc_walker,
+										   (void *) &context,
+										   0);
+
+	return context.win_location;
+}
+
+static bool
+locate_windowfunc_walker(Node *node, locate_windowfunc_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, WindowFunc))
+	{
+		if (((WindowFunc *) node)->location >= 0)
+		{
+			context->win_location = ((WindowFunc *) node)->location;
+			return true;		/* abort the tree traversal and return true */
+		}
+		/* else fall through to examine argument */
+	}
+	/* Mustn't recurse into subselects */
+	return expression_tree_walker(node, locate_windowfunc_walker,
+								  (void *) context);
+}
+
+/*
+ * checkExprHasSubLink -
+ *	Check if an expression contains a SubLink.
+ */
+bool
+checkExprHasSubLink(Node *node)
+{
+	/*
+	 * If a Query is passed, examine it --- but we should not recurse into
+	 * sub-Queries that are in its rangetable or CTE list.
+	 */
+	return query_or_expression_tree_walker(node,
+										   checkExprHasSubLink_walker,
+										   NULL,
+										   QTW_IGNORE_RC_SUBQUERIES);
+}
+
+static bool
+checkExprHasSubLink_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, SubLink))
+		return true;			/* abort the tree traversal and return true */
+	return expression_tree_walker(node, checkExprHasSubLink_walker, context);
+}
+
+/*
+ * Check for MULTIEXPR Param within expression tree
+ *
+ * We intentionally don't descend into SubLinks: only Params at the current
+ * query level are of interest.
+ */
+static bool
+contains_multiexpr_param(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Param))
+	{
+		if (((Param *) node)->paramkind == PARAM_MULTIEXPR)
+			return true;		/* abort the tree traversal and return true */
+		return false;
+	}
+	return expression_tree_walker(node, contains_multiexpr_param, context);
+}
+
+
+/*
+ * OffsetVarNodes - adjust Vars when appending one query's RT to another
+ *
+ * Find all Var nodes in the given tree with varlevelsup == sublevels_up,
+ * and increment their varno fields (rangetable indexes) by 'offset'.
+ * The varnosyn fields are adjusted similarly.  Also, adjust other nodes
+ * that contain rangetable indexes, such as RangeTblRef and JoinExpr.
+ *
+ * NOTE: although this has the form of a walker, we cheat and modify the
+ * nodes in-place.  The given expression tree should have been copied
+ * earlier to ensure that no unwanted side-effects occur!
+ */
+
+typedef struct
+{
+	int			offset;
+	int			sublevels_up;
+} OffsetVarNodes_context;
+
+static bool
+OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varlevelsup == context->sublevels_up)
+		{
+			var->varno += context->offset;
+			if (var->varnosyn > 0)
+				var->varnosyn += context->offset;
+		}
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+	{
+		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
+
+		if (context->sublevels_up == 0)
+			cexpr->cvarno += context->offset;
+		return false;
+	}
+	if (IsA(node, RangeTblRef))
+	{
+		RangeTblRef *rtr = (RangeTblRef *) node;
+
+		if (context->sublevels_up == 0)
+			rtr->rtindex += context->offset;
+		/* the subquery itself is visited separately */
+		return false;
+	}
+	if (IsA(node, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) node;
+
+		if (j->rtindex && context->sublevels_up == 0)
+			j->rtindex += context->offset;
+		/* fall through to examine children */
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		if (phv->phlevelsup == context->sublevels_up)
+		{
+			phv->phrels = offset_relid_set(phv->phrels,
+										   context->offset);
+		}
+		/* fall through to examine children */
+	}
+	if (IsA(node, AppendRelInfo))
+	{
+		AppendRelInfo *appinfo = (AppendRelInfo *) node;
+
+		if (context->sublevels_up == 0)
+		{
+			appinfo->parent_relid += context->offset;
+			appinfo->child_relid += context->offset;
+		}
+		/* fall through to examine children */
+	}
+	/* Shouldn't need to handle other planner auxiliary nodes here */
+	Assert(!IsA(node, PlanRowMark));
+	Assert(!IsA(node, SpecialJoinInfo));
+	Assert(!IsA(node, PlaceHolderInfo));
+	Assert(!IsA(node, MinMaxAggInfo));
+
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node, OffsetVarNodes_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	return expression_tree_walker(node, OffsetVarNodes_walker,
+								  (void *) context);
+}
+
+void
+OffsetVarNodes(Node *node, int offset, int sublevels_up)
+{
+	OffsetVarNodes_context context;
+
+	context.offset = offset;
+	context.sublevels_up = sublevels_up;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, go straight to query_tree_walker to make sure that
+	 * sublevels_up doesn't get incremented prematurely.
+	 */
+	if (node && IsA(node, Query))
+	{
+		Query	   *qry = (Query *) node;
+
+		/*
+		 * If we are starting at a Query, and sublevels_up is zero, then we
+		 * must also fix rangetable indexes in the Query itself --- namely
+		 * resultRelation, exclRelIndex and rowMarks entries.  sublevels_up
+		 * cannot be zero when recursing into a subquery, so there's no need
+		 * to have the same logic inside OffsetVarNodes_walker.
+		 */
+		if (sublevels_up == 0)
+		{
+			ListCell   *l;
+
+			if (qry->resultRelation)
+				qry->resultRelation += offset;
+
+			if (qry->onConflict && qry->onConflict->exclRelIndex)
+				qry->onConflict->exclRelIndex += offset;
+
+			foreach(l, qry->rowMarks)
+			{
+				RowMarkClause *rc = (RowMarkClause *) lfirst(l);
+
+				rc->rti += offset;
+			}
+		}
+		query_tree_walker(qry, OffsetVarNodes_walker,
+						  (void *) &context, 0);
+	}
+	else
+		OffsetVarNodes_walker(node, &context);
+}
+
+static Relids
+offset_relid_set(Relids relids, int offset)
+{
+	Relids		result = NULL;
+	int			rtindex;
+
+	rtindex = -1;
+	while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
+		result = bms_add_member(result, rtindex + offset);
+	return result;
+}
+
+/*
+ * ChangeVarNodes - adjust Var nodes for a specific change of RT index
+ *
+ * Find all Var nodes in the given tree belonging to a specific relation
+ * (identified by sublevels_up and rt_index), and change their varno fields
+ * to 'new_index'.  The varnosyn fields are changed too.  Also, adjust other
+ * nodes that contain rangetable indexes, such as RangeTblRef and JoinExpr.
+ *
+ * NOTE: although this has the form of a walker, we cheat and modify the
+ * nodes in-place.  The given expression tree should have been copied
+ * earlier to ensure that no unwanted side-effects occur!
+ */
+
+typedef struct
+{
+	int			rt_index;
+	int			new_index;
+	int			sublevels_up;
+} ChangeVarNodes_context;
+
+static bool
+ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varlevelsup == context->sublevels_up &&
+			var->varno == context->rt_index)
+		{
+			var->varno = context->new_index;
+			/* If the syntactic referent is same RTE, fix it too */
+			if (var->varnosyn == context->rt_index)
+				var->varnosyn = context->new_index;
+		}
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+	{
+		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
+
+		if (context->sublevels_up == 0 &&
+			cexpr->cvarno == context->rt_index)
+			cexpr->cvarno = context->new_index;
+		return false;
+	}
+	if (IsA(node, RangeTblRef))
+	{
+		RangeTblRef *rtr = (RangeTblRef *) node;
+
+		if (context->sublevels_up == 0 &&
+			rtr->rtindex == context->rt_index)
+			rtr->rtindex = context->new_index;
+		/* the subquery itself is visited separately */
+		return false;
+	}
+	if (IsA(node, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) node;
+
+		if (context->sublevels_up == 0 &&
+			j->rtindex == context->rt_index)
+			j->rtindex = context->new_index;
+		/* fall through to examine children */
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		if (phv->phlevelsup == context->sublevels_up)
+		{
+			phv->phrels = adjust_relid_set(phv->phrels,
+										   context->rt_index,
+										   context->new_index);
+		}
+		/* fall through to examine children */
+	}
+	if (IsA(node, PlanRowMark))
+	{
+		PlanRowMark *rowmark = (PlanRowMark *) node;
+
+		if (context->sublevels_up == 0)
+		{
+			if (rowmark->rti == context->rt_index)
+				rowmark->rti = context->new_index;
+			if (rowmark->prti == context->rt_index)
+				rowmark->prti = context->new_index;
+		}
+		return false;
+	}
+	if (IsA(node, AppendRelInfo))
+	{
+		AppendRelInfo *appinfo = (AppendRelInfo *) node;
+
+		if (context->sublevels_up == 0)
+		{
+			if (appinfo->parent_relid == context->rt_index)
+				appinfo->parent_relid = context->new_index;
+			if (appinfo->child_relid == context->rt_index)
+				appinfo->child_relid = context->new_index;
+		}
+		/* fall through to examine children */
+	}
+	/* Shouldn't need to handle other planner auxiliary nodes here */
+	Assert(!IsA(node, SpecialJoinInfo));
+	Assert(!IsA(node, PlaceHolderInfo));
+	Assert(!IsA(node, MinMaxAggInfo));
+
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node, ChangeVarNodes_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	return expression_tree_walker(node, ChangeVarNodes_walker,
+								  (void *) context);
+}
+
+void
+ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
+{
+	ChangeVarNodes_context context;
+
+	context.rt_index = rt_index;
+	context.new_index = new_index;
+	context.sublevels_up = sublevels_up;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, go straight to query_tree_walker to make sure that
+	 * sublevels_up doesn't get incremented prematurely.
+	 */
+	if (node && IsA(node, Query))
+	{
+		Query	   *qry = (Query *) node;
+
+		/*
+		 * If we are starting at a Query, and sublevels_up is zero, then we
+		 * must also fix rangetable indexes in the Query itself --- namely
+		 * resultRelation and rowMarks entries.  sublevels_up cannot be zero
+		 * when recursing into a subquery, so there's no need to have the same
+		 * logic inside ChangeVarNodes_walker.
+		 */
+		if (sublevels_up == 0)
+		{
+			ListCell   *l;
+
+			if (qry->resultRelation == rt_index)
+				qry->resultRelation = new_index;
+
+			/* this is unlikely to ever be used, but ... */
+			if (qry->onConflict && qry->onConflict->exclRelIndex == rt_index)
+				qry->onConflict->exclRelIndex = new_index;
+
+			foreach(l, qry->rowMarks)
+			{
+				RowMarkClause *rc = (RowMarkClause *) lfirst(l);
+
+				if (rc->rti == rt_index)
+					rc->rti = new_index;
+			}
+		}
+		query_tree_walker(qry, ChangeVarNodes_walker,
+						  (void *) &context, 0);
+	}
+	else
+		ChangeVarNodes_walker(node, &context);
+}
+
+/*
+ * Substitute newrelid for oldrelid in a Relid set
+ */
+static Relids
+adjust_relid_set(Relids relids, int oldrelid, int newrelid)
+{
+	if (bms_is_member(oldrelid, relids))
+	{
+		/* Ensure we have a modifiable copy */
+		relids = bms_copy(relids);
+		/* Remove old, add new */
+		relids = bms_del_member(relids, oldrelid);
+		relids = bms_add_member(relids, newrelid);
+	}
+	return relids;
+}
+
+/*
+ * IncrementVarSublevelsUp - adjust Var nodes when pushing them down in tree
+ *
+ * Find all Var nodes in the given tree having varlevelsup >= min_sublevels_up,
+ * and add delta_sublevels_up to their varlevelsup value.  This is needed when
+ * an expression that's correct for some nesting level is inserted into a
+ * subquery.  Ordinarily the initial call has min_sublevels_up == 0 so that
+ * all Vars are affected.  The point of min_sublevels_up is that we can
+ * increment it when we recurse into a sublink, so that local variables in
+ * that sublink are not affected, only outer references to vars that belong
+ * to the expression's original query level or parents thereof.
+ *
+ * Likewise for other nodes containing levelsup fields, such as Aggref.
+ *
+ * NOTE: although this has the form of a walker, we cheat and modify the
+ * Var nodes in-place.  The given expression tree should have been copied
+ * earlier to ensure that no unwanted side-effects occur!
+ */
+
+typedef struct
+{
+	int			delta_sublevels_up;
+	int			min_sublevels_up;
+} IncrementVarSublevelsUp_context;
+
+static bool
+IncrementVarSublevelsUp_walker(Node *node,
+							   IncrementVarSublevelsUp_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varlevelsup >= context->min_sublevels_up)
+			var->varlevelsup += context->delta_sublevels_up;
+		return false;			/* done here */
+	}
+	if (IsA(node, CurrentOfExpr))
+	{
+		/* this should not happen */
+		if (context->min_sublevels_up == 0)
+			elog(ERROR, "cannot push down CurrentOfExpr");
+		return false;
+	}
+	if (IsA(node, Aggref))
+	{
+		Aggref	   *agg = (Aggref *) node;
+
+		if (agg->agglevelsup >= context->min_sublevels_up)
+			agg->agglevelsup += context->delta_sublevels_up;
+		/* fall through to recurse into argument */
+	}
+	if (IsA(node, GroupingFunc))
+	{
+		GroupingFunc *grp = (GroupingFunc *) node;
+
+		if (grp->agglevelsup >= context->min_sublevels_up)
+			grp->agglevelsup += context->delta_sublevels_up;
+		/* fall through to recurse into argument */
+	}
+	if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		if (phv->phlevelsup >= context->min_sublevels_up)
+			phv->phlevelsup += context->delta_sublevels_up;
+		/* fall through to recurse into argument */
+	}
+	if (IsA(node, RangeTblEntry))
+	{
+		RangeTblEntry *rte = (RangeTblEntry *) node;
+
+		if (rte->rtekind == RTE_CTE)
+		{
+			if (rte->ctelevelsup >= context->min_sublevels_up)
+				rte->ctelevelsup += context->delta_sublevels_up;
+		}
+		return false;			/* allow range_table_walker to continue */
+	}
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->min_sublevels_up++;
+		result = query_tree_walker((Query *) node,
+								   IncrementVarSublevelsUp_walker,
+								   (void *) context,
+								   QTW_EXAMINE_RTES_BEFORE);
+		context->min_sublevels_up--;
+		return result;
+	}
+	return expression_tree_walker(node, IncrementVarSublevelsUp_walker,
+								  (void *) context);
+}
+
+void
+IncrementVarSublevelsUp(Node *node, int delta_sublevels_up,
+						int min_sublevels_up)
+{
+	IncrementVarSublevelsUp_context context;
+
+	context.delta_sublevels_up = delta_sublevels_up;
+	context.min_sublevels_up = min_sublevels_up;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	query_or_expression_tree_walker(node,
+									IncrementVarSublevelsUp_walker,
+									(void *) &context,
+									QTW_EXAMINE_RTES_BEFORE);
+}
+
+/*
+ * IncrementVarSublevelsUp_rtable -
+ *	Same as IncrementVarSublevelsUp, but to be invoked on a range table.
+ */
+void
+IncrementVarSublevelsUp_rtable(List *rtable, int delta_sublevels_up,
+							   int min_sublevels_up)
+{
+	IncrementVarSublevelsUp_context context;
+
+	context.delta_sublevels_up = delta_sublevels_up;
+	context.min_sublevels_up = min_sublevels_up;
+
+	range_table_walker(rtable,
+					   IncrementVarSublevelsUp_walker,
+					   (void *) &context,
+					   QTW_EXAMINE_RTES_BEFORE);
+}
+
+
+/*
+ * rangeTableEntry_used - detect whether an RTE is referenced somewhere
+ *	in var nodes or join or setOp trees of a query or expression.
+ */
+
+typedef struct
+{
+	int			rt_index;
+	int			sublevels_up;
+} rangeTableEntry_used_context;
+
+static bool
+rangeTableEntry_used_walker(Node *node,
+							rangeTableEntry_used_context *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varlevelsup == context->sublevels_up &&
+			var->varno == context->rt_index)
+			return true;
+		return false;
+	}
+	if (IsA(node, CurrentOfExpr))
+	{
+		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
+
+		if (context->sublevels_up == 0 &&
+			cexpr->cvarno == context->rt_index)
+			return true;
+		return false;
+	}
+	if (IsA(node, RangeTblRef))
+	{
+		RangeTblRef *rtr = (RangeTblRef *) node;
+
+		if (rtr->rtindex == context->rt_index &&
+			context->sublevels_up == 0)
+			return true;
+		/* the subquery itself is visited separately */
+		return false;
+	}
+	if (IsA(node, JoinExpr))
+	{
+		JoinExpr   *j = (JoinExpr *) node;
+
+		if (j->rtindex == context->rt_index &&
+			context->sublevels_up == 0)
+			return true;
+		/* fall through to examine children */
+	}
+	/* Shouldn't need to handle planner auxiliary nodes here */
+	Assert(!IsA(node, PlaceHolderVar));
+	Assert(!IsA(node, PlanRowMark));
+	Assert(!IsA(node, SpecialJoinInfo));
+	Assert(!IsA(node, AppendRelInfo));
+	Assert(!IsA(node, PlaceHolderInfo));
+	Assert(!IsA(node, MinMaxAggInfo));
+
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		bool		result;
+
+		context->sublevels_up++;
+		result = query_tree_walker((Query *) node, rangeTableEntry_used_walker,
+								   (void *) context, 0);
+		context->sublevels_up--;
+		return result;
+	}
+	return expression_tree_walker(node, rangeTableEntry_used_walker,
+								  (void *) context);
+}
+
+bool
+rangeTableEntry_used(Node *node, int rt_index, int sublevels_up)
+{
+	rangeTableEntry_used_context context;
+
+	context.rt_index = rt_index;
+	context.sublevels_up = sublevels_up;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	return query_or_expression_tree_walker(node,
+										   rangeTableEntry_used_walker,
+										   (void *) &context,
+										   0);
+}
+
+
+/*
+ * If the given Query is an INSERT ... SELECT construct, extract and
+ * return the sub-Query node that represents the SELECT part.  Otherwise
+ * return the given Query.
+ *
+ * If subquery_ptr is not NULL, then *subquery_ptr is set to the location
+ * of the link to the SELECT subquery inside parsetree, or NULL if not an
+ * INSERT ... SELECT.
+ *
+ * This is a hack needed because transformations on INSERT ... SELECTs that
+ * appear in rule actions should be applied to the source SELECT, not to the
+ * INSERT part.  Perhaps this can be cleaned up with redesigned querytrees.
+ */
+Query *
+getInsertSelectQuery(Query *parsetree, Query ***subquery_ptr)
+{
+	Query	   *selectquery;
+	RangeTblEntry *selectrte;
+	RangeTblRef *rtr;
+
+	if (subquery_ptr)
+		*subquery_ptr = NULL;
+
+	if (parsetree == NULL)
+		return parsetree;
+	if (parsetree->commandType != CMD_INSERT)
+		return parsetree;
+
+	/*
+	 * Currently, this is ONLY applied to rule-action queries, and so we
+	 * expect to find the OLD and NEW placeholder entries in the given query.
+	 * If they're not there, it must be an INSERT/SELECT in which they've been
+	 * pushed down to the SELECT.
+	 */
+	if (list_length(parsetree->rtable) >= 2 &&
+		strcmp(rt_fetch(PRS2_OLD_VARNO, parsetree->rtable)->eref->aliasname,
+			   "old") == 0 &&
+		strcmp(rt_fetch(PRS2_NEW_VARNO, parsetree->rtable)->eref->aliasname,
+			   "new") == 0)
+		return parsetree;
+	Assert(parsetree->jointree && IsA(parsetree->jointree, FromExpr));
+	if (list_length(parsetree->jointree->fromlist) != 1)
+		elog(ERROR, "expected to find SELECT subquery");
+	rtr = (RangeTblRef *) linitial(parsetree->jointree->fromlist);
+	if (!IsA(rtr, RangeTblRef))
+		elog(ERROR, "expected to find SELECT subquery");
+	selectrte = rt_fetch(rtr->rtindex, parsetree->rtable);
+	if (!(selectrte->rtekind == RTE_SUBQUERY &&
+		  selectrte->subquery &&
+		  IsA(selectrte->subquery, Query) &&
+		  selectrte->subquery->commandType == CMD_SELECT))
+		elog(ERROR, "expected to find SELECT subquery");
+	selectquery = selectrte->subquery;
+	if (list_length(selectquery->rtable) >= 2 &&
+		strcmp(rt_fetch(PRS2_OLD_VARNO, selectquery->rtable)->eref->aliasname,
+			   "old") == 0 &&
+		strcmp(rt_fetch(PRS2_NEW_VARNO, selectquery->rtable)->eref->aliasname,
+			   "new") == 0)
+	{
+		if (subquery_ptr)
+			*subquery_ptr = &(selectrte->subquery);
+		return selectquery;
+	}
+	elog(ERROR, "could not find rule placeholders");
+	return NULL;				/* not reached */
+}
+
+
+/*
+ * Add the given qualifier condition to the query's WHERE clause
+ */
+void
+AddQual(Query *parsetree, Node *qual)
+{
+	Node	   *copy;
+
+	if (qual == NULL)
+		return;
+
+	if (parsetree->commandType == CMD_UTILITY)
+	{
+		/*
+		 * There's noplace to put the qual on a utility statement.
+		 *
+		 * If it's a NOTIFY, silently ignore the qual; this means that the
+		 * NOTIFY will execute, whether or not there are any qualifying rows.
+		 * While clearly wrong, this is much more useful than refusing to
+		 * execute the rule at all, and extra NOTIFY events are harmless for
+		 * typical uses of NOTIFY.
+		 *
+		 * If it isn't a NOTIFY, error out, since unconditional execution of
+		 * other utility stmts is unlikely to be wanted.  (This case is not
+		 * currently allowed anyway, but keep the test for safety.)
+		 */
+		if (parsetree->utilityStmt && IsA(parsetree->utilityStmt, NotifyStmt))
+			return;
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("conditional utility statements are not implemented")));
+	}
+
+	if (parsetree->setOperations != NULL)
+	{
+		/*
+		 * There's noplace to put the qual on a setop statement, either. (This
+		 * could be fixed, but right now the planner simply ignores any qual
+		 * condition on a setop query.)
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
+	}
+
+	/* INTERSECT wants the original, but we need to copy - Jan */
+	copy = copyObject(qual);
+
+	parsetree->jointree->quals = make_and_qual(parsetree->jointree->quals,
+											   copy);
+
+	/*
+	 * We had better not have stuck an aggregate into the WHERE clause.
+	 */
+	Assert(!contain_aggs_of_level(copy, 0));
+
+	/*
+	 * Make sure query is marked correctly if added qual has sublinks. Need
+	 * not search qual when query is already marked.
+	 */
+	if (!parsetree->hasSubLinks)
+		parsetree->hasSubLinks = checkExprHasSubLink(copy);
+}
+
+
+/*
+ * Invert the given clause and add it to the WHERE qualifications of the
+ * given querytree.  Inversion means "x IS NOT TRUE", not just "NOT x",
+ * else we will do the wrong thing when x evaluates to NULL.
+ */
+void
+AddInvertedQual(Query *parsetree, Node *qual)
+{
+	BooleanTest *invqual;
+
+	if (qual == NULL)
+		return;
+
+	/* Need not copy input qual, because AddQual will... */
+	invqual = makeNode(BooleanTest);
+	invqual->arg = (Expr *) qual;
+	invqual->booltesttype = IS_NOT_TRUE;
+	invqual->location = -1;
+
+	AddQual(parsetree, (Node *) invqual);
+}
+
+
+/*
+ * replace_rte_variables() finds all Vars in an expression tree
+ * that reference a particular RTE, and replaces them with substitute
+ * expressions obtained from a caller-supplied callback function.
+ *
+ * When invoking replace_rte_variables on a portion of a Query, pass the
+ * address of the containing Query's hasSubLinks field as outer_hasSubLinks.
+ * Otherwise, pass NULL, but inserting a SubLink into a non-Query expression
+ * will then cause an error.
+ *
+ * Note: the business with inserted_sublink is needed to update hasSubLinks
+ * in subqueries when the replacement adds a subquery inside a subquery.
+ * Messy, isn't it?  We do not need to do similar pushups for hasAggs,
+ * because it isn't possible for this transformation to insert a level-zero
+ * aggregate reference into a subquery --- it could only insert outer aggs.
+ * Likewise for hasWindowFuncs.
+ *
+ * Note: usually, we'd not expose the mutator function or context struct
+ * for a function like this.  We do so because callbacks often find it
+ * convenient to recurse directly to the mutator on sub-expressions of
+ * what they will return.
+ */
+Node *
+replace_rte_variables(Node *node, int target_varno, int sublevels_up,
+					  replace_rte_variables_callback callback,
+					  void *callback_arg,
+					  bool *outer_hasSubLinks)
+{
+	Node	   *result;
+	replace_rte_variables_context context;
+
+	context.callback = callback;
+	context.callback_arg = callback_arg;
+	context.target_varno = target_varno;
+	context.sublevels_up = sublevels_up;
+
+	/*
+	 * We try to initialize inserted_sublink to true if there is no need to
+	 * detect new sublinks because the query already has some.
+	 */
+	if (node && IsA(node, Query))
+		context.inserted_sublink = ((Query *) node)->hasSubLinks;
+	else if (outer_hasSubLinks)
+		context.inserted_sublink = *outer_hasSubLinks;
+	else
+		context.inserted_sublink = false;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	result = query_or_expression_tree_mutator(node,
+											  replace_rte_variables_mutator,
+											  (void *) &context,
+											  0);
+
+	if (context.inserted_sublink)
+	{
+		if (result && IsA(result, Query))
+			((Query *) result)->hasSubLinks = true;
+		else if (outer_hasSubLinks)
+			*outer_hasSubLinks = true;
+		else
+			elog(ERROR, "replace_rte_variables inserted a SubLink, but has noplace to record it");
+	}
+
+	return result;
+}
+
+Node *
+replace_rte_variables_mutator(Node *node,
+							  replace_rte_variables_context *context)
+{
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varno == context->target_varno &&
+			var->varlevelsup == context->sublevels_up)
+		{
+			/* Found a matching variable, make the substitution */
+			Node	   *newnode;
+
+			newnode = context->callback(var, context);
+			/* Detect if we are adding a sublink to query */
+			if (!context->inserted_sublink)
+				context->inserted_sublink = checkExprHasSubLink(newnode);
+			return newnode;
+		}
+		/* otherwise fall through to copy the var normally */
+	}
+	else if (IsA(node, CurrentOfExpr))
+	{
+		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
+
+		if (cexpr->cvarno == context->target_varno &&
+			context->sublevels_up == 0)
+		{
+			/*
+			 * We get here if a WHERE CURRENT OF expression turns out to apply
+			 * to a view.  Someday we might be able to translate the
+			 * expression to apply to an underlying table of the view, but
+			 * right now it's not implemented.
+			 */
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("WHERE CURRENT OF on a view is not implemented")));
+		}
+		/* otherwise fall through to copy the expr normally */
+	}
+	else if (IsA(node, Query))
+	{
+		/* Recurse into RTE subquery or not-yet-planned sublink subquery */
+		Query	   *newnode;
+		bool		save_inserted_sublink;
+
+		context->sublevels_up++;
+		save_inserted_sublink = context->inserted_sublink;
+		context->inserted_sublink = ((Query *) node)->hasSubLinks;
+		newnode = query_tree_mutator((Query *) node,
+									 replace_rte_variables_mutator,
+									 (void *) context,
+									 0);
+		newnode->hasSubLinks |= context->inserted_sublink;
+		context->inserted_sublink = save_inserted_sublink;
+		context->sublevels_up--;
+		return (Node *) newnode;
+	}
+	return expression_tree_mutator(node, replace_rte_variables_mutator,
+								   (void *) context);
+}
+
+
+/*
+ * map_variable_attnos() finds all user-column Vars in an expression tree
+ * that reference a particular RTE, and adjusts their varattnos according
+ * to the given mapping array (varattno n is replaced by attno_map[n-1]).
+ * Vars for system columns are not modified.
+ *
+ * A zero in the mapping array represents a dropped column, which should not
+ * appear in the expression.
+ *
+ * If the expression tree contains a whole-row Var for the target RTE,
+ * *found_whole_row is set to true.  In addition, if to_rowtype is
+ * not InvalidOid, we replace the Var with a Var of that vartype, inserting
+ * a ConvertRowtypeExpr to map back to the rowtype expected by the expression.
+ * (Therefore, to_rowtype had better be a child rowtype of the rowtype of the
+ * RTE we're changing references to.)  Callers that don't provide to_rowtype
+ * should report an error if *found_whole_row is true; we don't do that here
+ * because we don't know exactly what wording for the error message would
+ * be most appropriate.  The caller will be aware of the context.
+ *
+ * This could be built using replace_rte_variables and a callback function,
+ * but since we don't ever need to insert sublinks, replace_rte_variables is
+ * overly complicated.
+ */
+
+typedef struct
+{
+	int			target_varno;	/* RTE index to search for */
+	int			sublevels_up;	/* (current) nesting depth */
+	const AttrMap *attno_map;	/* map array for user attnos */
+	Oid			to_rowtype;		/* change whole-row Vars to this type */
+	bool	   *found_whole_row;	/* output flag */
+} map_variable_attnos_context;
+
+static Node *
+map_variable_attnos_mutator(Node *node,
+							map_variable_attnos_context *context)
+{
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varno == context->target_varno &&
+			var->varlevelsup == context->sublevels_up)
+		{
+			/* Found a matching variable, make the substitution */
+			Var		   *newvar = (Var *) palloc(sizeof(Var));
+			int			attno = var->varattno;
+
+			*newvar = *var;		/* initially copy all fields of the Var */
+
+			if (attno > 0)
+			{
+				/* user-defined column, replace attno */
+				if (attno > context->attno_map->maplen ||
+					context->attno_map->attnums[attno - 1] == 0)
+					elog(ERROR, "unexpected varattno %d in expression to be mapped",
+						 attno);
+				newvar->varattno = context->attno_map->attnums[attno - 1];
+				/* If the syntactic referent is same RTE, fix it too */
+				if (newvar->varnosyn == context->target_varno)
+					newvar->varattnosyn = newvar->varattno;
+			}
+			else if (attno == 0)
+			{
+				/* whole-row variable, warn caller */
+				*(context->found_whole_row) = true;
+
+				/* If the caller expects us to convert the Var, do so. */
+				if (OidIsValid(context->to_rowtype) &&
+					context->to_rowtype != var->vartype)
+				{
+					ConvertRowtypeExpr *r;
+
+					/* This certainly won't work for a RECORD variable. */
+					Assert(var->vartype != RECORDOID);
+
+					/* Var itself is changed to the requested type. */
+					newvar->vartype = context->to_rowtype;
+
+					/*
+					 * Add a conversion node on top to convert back to the
+					 * original type expected by the expression.
+					 */
+					r = makeNode(ConvertRowtypeExpr);
+					r->arg = (Expr *) newvar;
+					r->resulttype = var->vartype;
+					r->convertformat = COERCE_IMPLICIT_CAST;
+					r->location = -1;
+
+					return (Node *) r;
+				}
+			}
+			return (Node *) newvar;
+		}
+		/* otherwise fall through to copy the var normally */
+	}
+	else if (IsA(node, ConvertRowtypeExpr))
+	{
+		ConvertRowtypeExpr *r = (ConvertRowtypeExpr *) node;
+		Var		   *var = (Var *) r->arg;
+
+		/*
+		 * If this is coercing a whole-row Var that we need to convert, then
+		 * just convert the Var without adding an extra ConvertRowtypeExpr.
+		 * Effectively we're simplifying var::parenttype::grandparenttype into
+		 * just var::grandparenttype.  This avoids building stacks of CREs if
+		 * this function is applied repeatedly.
+		 */
+		if (IsA(var, Var) &&
+			var->varno == context->target_varno &&
+			var->varlevelsup == context->sublevels_up &&
+			var->varattno == 0 &&
+			OidIsValid(context->to_rowtype) &&
+			context->to_rowtype != var->vartype)
+		{
+			ConvertRowtypeExpr *newnode;
+			Var		   *newvar = (Var *) palloc(sizeof(Var));
+
+			/* whole-row variable, warn caller */
+			*(context->found_whole_row) = true;
+
+			*newvar = *var;		/* initially copy all fields of the Var */
+
+			/* This certainly won't work for a RECORD variable. */
+			Assert(var->vartype != RECORDOID);
+
+			/* Var itself is changed to the requested type. */
+			newvar->vartype = context->to_rowtype;
+
+			newnode = (ConvertRowtypeExpr *) palloc(sizeof(ConvertRowtypeExpr));
+			*newnode = *r;		/* initially copy all fields of the CRE */
+			newnode->arg = (Expr *) newvar;
+
+			return (Node *) newnode;
+		}
+		/* otherwise fall through to process the expression normally */
+	}
+	else if (IsA(node, Query))
+	{
+		/* Recurse into RTE subquery or not-yet-planned sublink subquery */
+		Query	   *newnode;
+
+		context->sublevels_up++;
+		newnode = query_tree_mutator((Query *) node,
+									 map_variable_attnos_mutator,
+									 (void *) context,
+									 0);
+		context->sublevels_up--;
+		return (Node *) newnode;
+	}
+	return expression_tree_mutator(node, map_variable_attnos_mutator,
+								   (void *) context);
+}
+
+Node *
+map_variable_attnos(Node *node,
+					int target_varno, int sublevels_up,
+					const AttrMap *attno_map,
+					Oid to_rowtype, bool *found_whole_row)
+{
+	map_variable_attnos_context context;
+
+	context.target_varno = target_varno;
+	context.sublevels_up = sublevels_up;
+	context.attno_map = attno_map;
+	context.to_rowtype = to_rowtype;
+	context.found_whole_row = found_whole_row;
+
+	*found_whole_row = false;
+
+	/*
+	 * Must be prepared to start with a Query or a bare expression tree; if
+	 * it's a Query, we don't want to increment sublevels_up.
+	 */
+	return query_or_expression_tree_mutator(node,
+											map_variable_attnos_mutator,
+											(void *) &context,
+											0);
+}
+
+
+/*
+ * ReplaceVarsFromTargetList - replace Vars with items from a targetlist
+ *
+ * Vars matching target_varno and sublevels_up are replaced by the
+ * entry with matching resno from targetlist, if there is one.
+ *
+ * If there is no matching resno for such a Var, the action depends on the
+ * nomatch_option:
+ *	REPLACEVARS_REPORT_ERROR: throw an error
+ *	REPLACEVARS_CHANGE_VARNO: change Var's varno to nomatch_varno
+ *	REPLACEVARS_SUBSTITUTE_NULL: replace Var with a NULL Const of same type
+ *
+ * The caller must also provide target_rte, the RTE describing the target
+ * relation.  This is needed to handle whole-row Vars referencing the target.
+ * We expand such Vars into RowExpr constructs.
+ *
+ * outer_hasSubLinks works the same as for replace_rte_variables().
+ */
+
+typedef struct
+{
+	RangeTblEntry *target_rte;
+	List	   *targetlist;
+	ReplaceVarsNoMatchOption nomatch_option;
+	int			nomatch_varno;
+} ReplaceVarsFromTargetList_context;
+
+static Node *
+ReplaceVarsFromTargetList_callback(Var *var,
+								   replace_rte_variables_context *context)
+{
+	ReplaceVarsFromTargetList_context *rcon = (ReplaceVarsFromTargetList_context *) context->callback_arg;
+	TargetEntry *tle;
+
+	if (var->varattno == InvalidAttrNumber)
+	{
+		/* Must expand whole-tuple reference into RowExpr */
+		RowExpr    *rowexpr;
+		List	   *colnames;
+		List	   *fields;
+
+		/*
+		 * If generating an expansion for a var of a named rowtype (ie, this
+		 * is a plain relation RTE), then we must include dummy items for
+		 * dropped columns.  If the var is RECORD (ie, this is a JOIN), then
+		 * omit dropped columns.  In the latter case, attach column names to
+		 * the RowExpr for use of the executor and ruleutils.c.
+		 */
+		expandRTE(rcon->target_rte,
+				  var->varno, var->varlevelsup, var->location,
+				  (var->vartype != RECORDOID),
+				  &colnames, &fields);
+		/* Adjust the generated per-field Vars... */
+		fields = (List *) replace_rte_variables_mutator((Node *) fields,
+														context);
+		rowexpr = makeNode(RowExpr);
+		rowexpr->args = fields;
+		rowexpr->row_typeid = var->vartype;
+		rowexpr->row_format = COERCE_IMPLICIT_CAST;
+		rowexpr->colnames = (var->vartype == RECORDOID) ? colnames : NIL;
+		rowexpr->location = var->location;
+
+		return (Node *) rowexpr;
+	}
+
+	/* Normal case referencing one targetlist element */
+	tle = get_tle_by_resno(rcon->targetlist, var->varattno);
+
+	if (tle == NULL || tle->resjunk)
+	{
+		/* Failed to find column in targetlist */
+		switch (rcon->nomatch_option)
+		{
+			case REPLACEVARS_REPORT_ERROR:
+				/* fall through, throw error below */
+				break;
+
+			case REPLACEVARS_CHANGE_VARNO:
+				var = (Var *) copyObject(var);
+				var->varno = rcon->nomatch_varno;
+				/* we leave the syntactic referent alone */
+				return (Node *) var;
+
+			case REPLACEVARS_SUBSTITUTE_NULL:
+
+				/*
+				 * If Var is of domain type, we should add a CoerceToDomain
+				 * node, in case there is a NOT NULL domain constraint.
+				 */
+				return coerce_to_domain((Node *) makeNullConst(var->vartype,
+															   var->vartypmod,
+															   var->varcollid),
+										InvalidOid, -1,
+										var->vartype,
+										COERCION_IMPLICIT,
+										COERCE_IMPLICIT_CAST,
+										-1,
+										false);
+		}
+		elog(ERROR, "could not find replacement targetlist entry for attno %d",
+			 var->varattno);
+		return NULL;			/* keep compiler quiet */
+	}
+	else
+	{
+		/* Make a copy of the tlist item to return */
+		Expr	   *newnode = copyObject(tle->expr);
+
+		/* Must adjust varlevelsup if tlist item is from higher query */
+		if (var->varlevelsup > 0)
+			IncrementVarSublevelsUp((Node *) newnode, var->varlevelsup, 0);
+
+		/*
+		 * Check to see if the tlist item contains a PARAM_MULTIEXPR Param,
+		 * and throw error if so.  This case could only happen when expanding
+		 * an ON UPDATE rule's NEW variable and the referenced tlist item in
+		 * the original UPDATE command is part of a multiple assignment. There
+		 * seems no practical way to handle such cases without multiple
+		 * evaluation of the multiple assignment's sub-select, which would
+		 * create semantic oddities that users of rules would probably prefer
+		 * not to cope with.  So treat it as an unimplemented feature.
+		 */
+		if (contains_multiexpr_param((Node *) newnode, NULL))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("NEW variables in ON UPDATE rules cannot reference columns that are part of a multiple assignment in the subject UPDATE command")));
+
+		return (Node *) newnode;
+	}
+}
+
+Node *
+ReplaceVarsFromTargetList(Node *node,
+						  int target_varno, int sublevels_up,
+						  RangeTblEntry *target_rte,
+						  List *targetlist,
+						  ReplaceVarsNoMatchOption nomatch_option,
+						  int nomatch_varno,
+						  bool *outer_hasSubLinks)
+{
+	ReplaceVarsFromTargetList_context context;
+
+	context.target_rte = target_rte;
+	context.targetlist = targetlist;
+	context.nomatch_option = nomatch_option;
+	context.nomatch_varno = nomatch_varno;
+
+	return replace_rte_variables(node, target_varno, sublevels_up,
+								 ReplaceVarsFromTargetList_callback,
+								 (void *) &context,
+								 outer_hasSubLinks);
+}