Adding upstream version 14.5.upstream/14.5upstream

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

1 files changed, 5200 insertions, 0 deletions

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
new file mode 100644
index 0000000..9d7aa8b
--- /dev/null
+++ b/src/backend/optimizer/util/clauses.c
@@ -0,0 +1,5200 @@
+/*-------------------------------------------------------------------------
+ *
+ * clauses.c
+ *	  routines to manipulate qualification clauses
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/util/clauses.c
+ *
+ * HISTORY
+ *	  AUTHOR			DATE			MAJOR EVENT
+ *	  Andrew Yu			Nov 3, 1994		clause.c and clauses.c combined
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "catalog/pg_aggregate.h"
+#include "catalog/pg_class.h"
+#include "catalog/pg_language.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
+#include "executor/executor.h"
+#include "executor/functions.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "nodes/subscripting.h"
+#include "nodes/supportnodes.h"
+#include "optimizer/clauses.h"
+#include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
+#include "optimizer/plancat.h"
+#include "optimizer/planmain.h"
+#include "parser/analyze.h"
+#include "parser/parse_agg.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_func.h"
+#include "rewrite/rewriteHandler.h"
+#include "rewrite/rewriteManip.h"
+#include "tcop/tcopprot.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/datum.h"
+#include "utils/fmgroids.h"
+#include "utils/lsyscache.h"
+#include "utils/memutils.h"
+#include "utils/syscache.h"
+#include "utils/typcache.h"
+
+typedef struct
+{
+	ParamListInfo boundParams;
+	PlannerInfo *root;
+	List	   *active_fns;
+	Node	   *case_val;
+	bool		estimate;
+} eval_const_expressions_context;
+
+typedef struct
+{
+	int			nargs;
+	List	   *args;
+	int		   *usecounts;
+} substitute_actual_parameters_context;
+
+typedef struct
+{
+	int			nargs;
+	List	   *args;
+	int			sublevels_up;
+} substitute_actual_srf_parameters_context;
+
+typedef struct
+{
+	char	   *proname;
+	char	   *prosrc;
+} inline_error_callback_arg;
+
+typedef struct
+{
+	char		max_hazard;		/* worst proparallel hazard found so far */
+	char		max_interesting;	/* worst proparallel hazard of interest */
+	List	   *safe_param_ids; /* PARAM_EXEC Param IDs to treat as safe */
+} max_parallel_hazard_context;
+
+static bool contain_agg_clause_walker(Node *node, void *context);
+static bool find_window_functions_walker(Node *node, WindowFuncLists *lists);
+static bool contain_subplans_walker(Node *node, void *context);
+static bool contain_mutable_functions_walker(Node *node, void *context);
+static bool contain_volatile_functions_walker(Node *node, void *context);
+static bool contain_volatile_functions_not_nextval_walker(Node *node, void *context);
+static bool max_parallel_hazard_walker(Node *node,
+									   max_parallel_hazard_context *context);
+static bool contain_nonstrict_functions_walker(Node *node, void *context);
+static bool contain_exec_param_walker(Node *node, List *param_ids);
+static bool contain_context_dependent_node(Node *clause);
+static bool contain_context_dependent_node_walker(Node *node, int *flags);
+static bool contain_leaked_vars_walker(Node *node, void *context);
+static Relids find_nonnullable_rels_walker(Node *node, bool top_level);
+static List *find_nonnullable_vars_walker(Node *node, bool top_level);
+static bool is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK);
+static bool convert_saop_to_hashed_saop_walker(Node *node, void *context);
+static Node *eval_const_expressions_mutator(Node *node,
+											eval_const_expressions_context *context);
+static bool contain_non_const_walker(Node *node, void *context);
+static bool ece_function_is_safe(Oid funcid,
+								 eval_const_expressions_context *context);
+static List *simplify_or_arguments(List *args,
+								   eval_const_expressions_context *context,
+								   bool *haveNull, bool *forceTrue);
+static List *simplify_and_arguments(List *args,
+									eval_const_expressions_context *context,
+									bool *haveNull, bool *forceFalse);
+static Node *simplify_boolean_equality(Oid opno, List *args);
+static Expr *simplify_function(Oid funcid,
+							   Oid result_type, int32 result_typmod,
+							   Oid result_collid, Oid input_collid, List **args_p,
+							   bool funcvariadic, bool process_args, bool allow_non_const,
+							   eval_const_expressions_context *context);
+static List *reorder_function_arguments(List *args, int pronargs,
+										HeapTuple func_tuple);
+static List *add_function_defaults(List *args, int pronargs,
+								   HeapTuple func_tuple);
+static List *fetch_function_defaults(HeapTuple func_tuple);
+static void recheck_cast_function_args(List *args, Oid result_type,
+									   Oid *proargtypes, int pronargs,
+									   HeapTuple func_tuple);
+static Expr *evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
+							   Oid result_collid, Oid input_collid, List *args,
+							   bool funcvariadic,
+							   HeapTuple func_tuple,
+							   eval_const_expressions_context *context);
+static Expr *inline_function(Oid funcid, Oid result_type, Oid result_collid,
+							 Oid input_collid, List *args,
+							 bool funcvariadic,
+							 HeapTuple func_tuple,
+							 eval_const_expressions_context *context);
+static Node *substitute_actual_parameters(Node *expr, int nargs, List *args,
+										  int *usecounts);
+static Node *substitute_actual_parameters_mutator(Node *node,
+												  substitute_actual_parameters_context *context);
+static void sql_inline_error_callback(void *arg);
+static Query *substitute_actual_srf_parameters(Query *expr,
+											   int nargs, List *args);
+static Node *substitute_actual_srf_parameters_mutator(Node *node,
+													  substitute_actual_srf_parameters_context *context);
+static bool pull_paramids_walker(Node *node, Bitmapset **context);
+
+
+/*****************************************************************************
+ *		Aggregate-function clause manipulation
+ *****************************************************************************/
+
+/*
+ * contain_agg_clause
+ *	  Recursively search for Aggref/GroupingFunc nodes within a clause.
+ *
+ *	  Returns true if any aggregate found.
+ *
+ * This does not descend into subqueries, and so should be used only after
+ * reduction of sublinks to subplans, or in contexts where it's known there
+ * are no subqueries.  There mustn't be outer-aggregate references either.
+ *
+ * (If you want something like this but able to deal with subqueries,
+ * see rewriteManip.c's contain_aggs_of_level().)
+ */
+bool
+contain_agg_clause(Node *clause)
+{
+	return contain_agg_clause_walker(clause, NULL);
+}
+
+static bool
+contain_agg_clause_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		Assert(((Aggref *) node)->agglevelsup == 0);
+		return true;			/* abort the tree traversal and return true */
+	}
+	if (IsA(node, GroupingFunc))
+	{
+		Assert(((GroupingFunc *) node)->agglevelsup == 0);
+		return true;			/* abort the tree traversal and return true */
+	}
+	Assert(!IsA(node, SubLink));
+	return expression_tree_walker(node, contain_agg_clause_walker, context);
+}
+
+/*****************************************************************************
+ *		Window-function clause manipulation
+ *****************************************************************************/
+
+/*
+ * contain_window_function
+ *	  Recursively search for WindowFunc nodes within a clause.
+ *
+ * Since window functions don't have level fields, but are hard-wired to
+ * be associated with the current query level, this is just the same as
+ * rewriteManip.c's function.
+ */
+bool
+contain_window_function(Node *clause)
+{
+	return contain_windowfuncs(clause);
+}
+
+/*
+ * find_window_functions
+ *	  Locate all the WindowFunc nodes in an expression tree, and organize
+ *	  them by winref ID number.
+ *
+ * Caller must provide an upper bound on the winref IDs expected in the tree.
+ */
+WindowFuncLists *
+find_window_functions(Node *clause, Index maxWinRef)
+{
+	WindowFuncLists *lists = palloc(sizeof(WindowFuncLists));
+
+	lists->numWindowFuncs = 0;
+	lists->maxWinRef = maxWinRef;
+	lists->windowFuncs = (List **) palloc0((maxWinRef + 1) * sizeof(List *));
+	(void) find_window_functions_walker(clause, lists);
+	return lists;
+}
+
+static bool
+find_window_functions_walker(Node *node, WindowFuncLists *lists)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, WindowFunc))
+	{
+		WindowFunc *wfunc = (WindowFunc *) node;
+
+		/* winref is unsigned, so one-sided test is OK */
+		if (wfunc->winref > lists->maxWinRef)
+			elog(ERROR, "WindowFunc contains out-of-range winref %u",
+				 wfunc->winref);
+		/* eliminate duplicates, so that we avoid repeated computation */
+		if (!list_member(lists->windowFuncs[wfunc->winref], wfunc))
+		{
+			lists->windowFuncs[wfunc->winref] =
+				lappend(lists->windowFuncs[wfunc->winref], wfunc);
+			lists->numWindowFuncs++;
+		}
+
+		/*
+		 * We assume that the parser checked that there are no window
+		 * functions in the arguments or filter clause.  Hence, we need not
+		 * recurse into them.  (If either the parser or the planner screws up
+		 * on this point, the executor will still catch it; see ExecInitExpr.)
+		 */
+		return false;
+	}
+	Assert(!IsA(node, SubLink));
+	return expression_tree_walker(node, find_window_functions_walker,
+								  (void *) lists);
+}
+
+
+/*****************************************************************************
+ *		Support for expressions returning sets
+ *****************************************************************************/
+
+/*
+ * expression_returns_set_rows
+ *	  Estimate the number of rows returned by a set-returning expression.
+ *	  The result is 1 if it's not a set-returning expression.
+ *
+ * We should only examine the top-level function or operator; it used to be
+ * appropriate to recurse, but not anymore.  (Even if there are more SRFs in
+ * the function's inputs, their multipliers are accounted for separately.)
+ *
+ * Note: keep this in sync with expression_returns_set() in nodes/nodeFuncs.c.
+ */
+double
+expression_returns_set_rows(PlannerInfo *root, Node *clause)
+{
+	if (clause == NULL)
+		return 1.0;
+	if (IsA(clause, FuncExpr))
+	{
+		FuncExpr   *expr = (FuncExpr *) clause;
+
+		if (expr->funcretset)
+			return clamp_row_est(get_function_rows(root, expr->funcid, clause));
+	}
+	if (IsA(clause, OpExpr))
+	{
+		OpExpr	   *expr = (OpExpr *) clause;
+
+		if (expr->opretset)
+		{
+			set_opfuncid(expr);
+			return clamp_row_est(get_function_rows(root, expr->opfuncid, clause));
+		}
+	}
+	return 1.0;
+}
+
+
+/*****************************************************************************
+ *		Subplan clause manipulation
+ *****************************************************************************/
+
+/*
+ * contain_subplans
+ *	  Recursively search for subplan nodes within a clause.
+ *
+ * If we see a SubLink node, we will return true.  This is only possible if
+ * the expression tree hasn't yet been transformed by subselect.c.  We do not
+ * know whether the node will produce a true subplan or just an initplan,
+ * but we make the conservative assumption that it will be a subplan.
+ *
+ * Returns true if any subplan found.
+ */
+bool
+contain_subplans(Node *clause)
+{
+	return contain_subplans_walker(clause, NULL);
+}
+
+static bool
+contain_subplans_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, SubPlan) ||
+		IsA(node, AlternativeSubPlan) ||
+		IsA(node, SubLink))
+		return true;			/* abort the tree traversal and return true */
+	return expression_tree_walker(node, contain_subplans_walker, context);
+}
+
+
+/*****************************************************************************
+ *		Check clauses for mutable functions
+ *****************************************************************************/
+
+/*
+ * contain_mutable_functions
+ *	  Recursively search for mutable functions within a clause.
+ *
+ * Returns true if any mutable function (or operator implemented by a
+ * mutable function) is found.  This test is needed so that we don't
+ * mistakenly think that something like "WHERE random() < 0.5" can be treated
+ * as a constant qualification.
+ *
+ * We will recursively look into Query nodes (i.e., SubLink sub-selects)
+ * but not into SubPlans.  See comments for contain_volatile_functions().
+ */
+bool
+contain_mutable_functions(Node *clause)
+{
+	return contain_mutable_functions_walker(clause, NULL);
+}
+
+static bool
+contain_mutable_functions_checker(Oid func_id, void *context)
+{
+	return (func_volatile(func_id) != PROVOLATILE_IMMUTABLE);
+}
+
+static bool
+contain_mutable_functions_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	/* Check for mutable functions in node itself */
+	if (check_functions_in_node(node, contain_mutable_functions_checker,
+								context))
+		return true;
+
+	if (IsA(node, SQLValueFunction))
+	{
+		/* all variants of SQLValueFunction are stable */
+		return true;
+	}
+
+	if (IsA(node, NextValueExpr))
+	{
+		/* NextValueExpr is volatile */
+		return true;
+	}
+
+	/*
+	 * It should be safe to treat MinMaxExpr as immutable, because it will
+	 * depend on a non-cross-type btree comparison function, and those should
+	 * always be immutable.  Treating XmlExpr as immutable is more dubious,
+	 * and treating CoerceToDomain as immutable is outright dangerous.  But we
+	 * have done so historically, and changing this would probably cause more
+	 * problems than it would fix.  In practice, if you have a non-immutable
+	 * domain constraint you are in for pain anyhow.
+	 */
+
+	/* Recurse to check arguments */
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		return query_tree_walker((Query *) node,
+								 contain_mutable_functions_walker,
+								 context, 0);
+	}
+	return expression_tree_walker(node, contain_mutable_functions_walker,
+								  context);
+}
+
+
+/*****************************************************************************
+ *		Check clauses for volatile functions
+ *****************************************************************************/
+
+/*
+ * contain_volatile_functions
+ *	  Recursively search for volatile functions within a clause.
+ *
+ * Returns true if any volatile function (or operator implemented by a
+ * volatile function) is found. This test prevents, for example,
+ * invalid conversions of volatile expressions into indexscan quals.
+ *
+ * We will recursively look into Query nodes (i.e., SubLink sub-selects)
+ * but not into SubPlans.  This is a bit odd, but intentional.  If we are
+ * looking at a SubLink, we are probably deciding whether a query tree
+ * transformation is safe, and a contained sub-select should affect that;
+ * for example, duplicating a sub-select containing a volatile function
+ * would be bad.  However, once we've got to the stage of having SubPlans,
+ * subsequent planning need not consider volatility within those, since
+ * the executor won't change its evaluation rules for a SubPlan based on
+ * volatility.
+ *
+ * For some node types, for example, RestrictInfo and PathTarget, we cache
+ * whether we found any volatile functions or not and reuse that value in any
+ * future checks for that node.  All of the logic for determining if the
+ * cached value should be set to VOLATILITY_NOVOLATILE or VOLATILITY_VOLATILE
+ * belongs in this function.  Any code which makes changes to these nodes
+ * which could change the outcome this function must set the cached value back
+ * to VOLATILITY_UNKNOWN.  That allows this function to redetermine the
+ * correct value during the next call, should we need to redetermine if the
+ * node contains any volatile functions again in the future.
+ */
+bool
+contain_volatile_functions(Node *clause)
+{
+	return contain_volatile_functions_walker(clause, NULL);
+}
+
+static bool
+contain_volatile_functions_checker(Oid func_id, void *context)
+{
+	return (func_volatile(func_id) == PROVOLATILE_VOLATILE);
+}
+
+static bool
+contain_volatile_functions_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	/* Check for volatile functions in node itself */
+	if (check_functions_in_node(node, contain_volatile_functions_checker,
+								context))
+		return true;
+
+	if (IsA(node, NextValueExpr))
+	{
+		/* NextValueExpr is volatile */
+		return true;
+	}
+
+	if (IsA(node, RestrictInfo))
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) node;
+
+		/*
+		 * For RestrictInfo, check if we've checked the volatility of it
+		 * before.  If so, we can just use the cached value and not bother
+		 * checking it again.  Otherwise, check it and cache if whether we
+		 * found any volatile functions.
+		 */
+		if (rinfo->has_volatile == VOLATILITY_NOVOLATILE)
+			return false;
+		else if (rinfo->has_volatile == VOLATILITY_VOLATILE)
+			return true;
+		else
+		{
+			bool		hasvolatile;
+
+			hasvolatile = contain_volatile_functions_walker((Node *) rinfo->clause,
+															context);
+			if (hasvolatile)
+				rinfo->has_volatile = VOLATILITY_VOLATILE;
+			else
+				rinfo->has_volatile = VOLATILITY_NOVOLATILE;
+
+			return hasvolatile;
+		}
+	}
+
+	if (IsA(node, PathTarget))
+	{
+		PathTarget *target = (PathTarget *) node;
+
+		/*
+		 * We also do caching for PathTarget the same as we do above for
+		 * RestrictInfos.
+		 */
+		if (target->has_volatile_expr == VOLATILITY_NOVOLATILE)
+			return false;
+		else if (target->has_volatile_expr == VOLATILITY_VOLATILE)
+			return true;
+		else
+		{
+			bool		hasvolatile;
+
+			hasvolatile = contain_volatile_functions_walker((Node *) target->exprs,
+															context);
+
+			if (hasvolatile)
+				target->has_volatile_expr = VOLATILITY_VOLATILE;
+			else
+				target->has_volatile_expr = VOLATILITY_NOVOLATILE;
+
+			return hasvolatile;
+		}
+	}
+
+	/*
+	 * See notes in contain_mutable_functions_walker about why we treat
+	 * MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
+	 * SQLValueFunction is stable.  Hence, none of them are of interest here.
+	 */
+
+	/* Recurse to check arguments */
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		return query_tree_walker((Query *) node,
+								 contain_volatile_functions_walker,
+								 context, 0);
+	}
+	return expression_tree_walker(node, contain_volatile_functions_walker,
+								  context);
+}
+
+/*
+ * Special purpose version of contain_volatile_functions() for use in COPY:
+ * ignore nextval(), but treat all other functions normally.
+ */
+bool
+contain_volatile_functions_not_nextval(Node *clause)
+{
+	return contain_volatile_functions_not_nextval_walker(clause, NULL);
+}
+
+static bool
+contain_volatile_functions_not_nextval_checker(Oid func_id, void *context)
+{
+	return (func_id != F_NEXTVAL &&
+			func_volatile(func_id) == PROVOLATILE_VOLATILE);
+}
+
+static bool
+contain_volatile_functions_not_nextval_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	/* Check for volatile functions in node itself */
+	if (check_functions_in_node(node,
+								contain_volatile_functions_not_nextval_checker,
+								context))
+		return true;
+
+	/*
+	 * See notes in contain_mutable_functions_walker about why we treat
+	 * MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
+	 * SQLValueFunction is stable.  Hence, none of them are of interest here.
+	 * Also, since we're intentionally ignoring nextval(), presumably we
+	 * should ignore NextValueExpr.
+	 */
+
+	/* Recurse to check arguments */
+	if (IsA(node, Query))
+	{
+		/* Recurse into subselects */
+		return query_tree_walker((Query *) node,
+								 contain_volatile_functions_not_nextval_walker,
+								 context, 0);
+	}
+	return expression_tree_walker(node,
+								  contain_volatile_functions_not_nextval_walker,
+								  context);
+}
+
+
+/*****************************************************************************
+ *		Check queries for parallel unsafe and/or restricted constructs
+ *****************************************************************************/
+
+/*
+ * max_parallel_hazard
+ *		Find the worst parallel-hazard level in the given query
+ *
+ * Returns the worst function hazard property (the earliest in this list:
+ * PROPARALLEL_UNSAFE, PROPARALLEL_RESTRICTED, PROPARALLEL_SAFE) that can
+ * be found in the given parsetree.  We use this to find out whether the query
+ * can be parallelized at all.  The caller will also save the result in
+ * PlannerGlobal so as to short-circuit checks of portions of the querytree
+ * later, in the common case where everything is SAFE.
+ */
+char
+max_parallel_hazard(Query *parse)
+{
+	max_parallel_hazard_context context;
+
+	context.max_hazard = PROPARALLEL_SAFE;
+	context.max_interesting = PROPARALLEL_UNSAFE;
+	context.safe_param_ids = NIL;
+	(void) max_parallel_hazard_walker((Node *) parse, &context);
+	return context.max_hazard;
+}
+
+/*
+ * is_parallel_safe
+ *		Detect whether the given expr contains only parallel-safe functions
+ *
+ * root->glob->maxParallelHazard must previously have been set to the
+ * result of max_parallel_hazard() on the whole query.
+ */
+bool
+is_parallel_safe(PlannerInfo *root, Node *node)
+{
+	max_parallel_hazard_context context;
+	PlannerInfo *proot;
+	ListCell   *l;
+
+	/*
+	 * Even if the original querytree contained nothing unsafe, we need to
+	 * search the expression if we have generated any PARAM_EXEC Params while
+	 * planning, because those are parallel-restricted and there might be one
+	 * in this expression.  But otherwise we don't need to look.
+	 */
+	if (root->glob->maxParallelHazard == PROPARALLEL_SAFE &&
+		root->glob->paramExecTypes == NIL)
+		return true;
+	/* Else use max_parallel_hazard's search logic, but stop on RESTRICTED */
+	context.max_hazard = PROPARALLEL_SAFE;
+	context.max_interesting = PROPARALLEL_RESTRICTED;
+	context.safe_param_ids = NIL;
+
+	/*
+	 * The params that refer to the same or parent query level are considered
+	 * parallel-safe.  The idea is that we compute such params at Gather or
+	 * Gather Merge node and pass their value to workers.
+	 */
+	for (proot = root; proot != NULL; proot = proot->parent_root)
+	{
+		foreach(l, proot->init_plans)
+		{
+			SubPlan    *initsubplan = (SubPlan *) lfirst(l);
+
+			context.safe_param_ids = list_concat(context.safe_param_ids,
+												 initsubplan->setParam);
+		}
+	}
+
+	return !max_parallel_hazard_walker(node, &context);
+}
+
+/* core logic for all parallel-hazard checks */
+static bool
+max_parallel_hazard_test(char proparallel, max_parallel_hazard_context *context)
+{
+	switch (proparallel)
+	{
+		case PROPARALLEL_SAFE:
+			/* nothing to see here, move along */
+			break;
+		case PROPARALLEL_RESTRICTED:
+			/* increase max_hazard to RESTRICTED */
+			Assert(context->max_hazard != PROPARALLEL_UNSAFE);
+			context->max_hazard = proparallel;
+			/* done if we are not expecting any unsafe functions */
+			if (context->max_interesting == proparallel)
+				return true;
+			break;
+		case PROPARALLEL_UNSAFE:
+			context->max_hazard = proparallel;
+			/* we're always done at the first unsafe construct */
+			return true;
+		default:
+			elog(ERROR, "unrecognized proparallel value \"%c\"", proparallel);
+			break;
+	}
+	return false;
+}
+
+/* check_functions_in_node callback */
+static bool
+max_parallel_hazard_checker(Oid func_id, void *context)
+{
+	return max_parallel_hazard_test(func_parallel(func_id),
+									(max_parallel_hazard_context *) context);
+}
+
+static bool
+max_parallel_hazard_walker(Node *node, max_parallel_hazard_context *context)
+{
+	if (node == NULL)
+		return false;
+
+	/* Check for hazardous functions in node itself */
+	if (check_functions_in_node(node, max_parallel_hazard_checker,
+								context))
+		return true;
+
+	/*
+	 * It should be OK to treat MinMaxExpr as parallel-safe, since btree
+	 * opclass support functions are generally parallel-safe.  XmlExpr is a
+	 * bit more dubious but we can probably get away with it.  We err on the
+	 * side of caution by treating CoerceToDomain as parallel-restricted.
+	 * (Note: in principle that's wrong because a domain constraint could
+	 * contain a parallel-unsafe function; but useful constraints probably
+	 * never would have such, and assuming they do would cripple use of
+	 * parallel query in the presence of domain types.)  SQLValueFunction
+	 * should be safe in all cases.  NextValueExpr is parallel-unsafe.
+	 */
+	if (IsA(node, CoerceToDomain))
+	{
+		if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
+			return true;
+	}
+
+	else if (IsA(node, NextValueExpr))
+	{
+		if (max_parallel_hazard_test(PROPARALLEL_UNSAFE, context))
+			return true;
+	}
+
+	/*
+	 * Treat window functions as parallel-restricted because we aren't sure
+	 * whether the input row ordering is fully deterministic, and the output
+	 * of window functions might vary across workers if not.  (In some cases,
+	 * like where the window frame orders by a primary key, we could relax
+	 * this restriction.  But it doesn't currently seem worth expending extra
+	 * effort to do so.)
+	 */
+	else if (IsA(node, WindowFunc))
+	{
+		if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
+			return true;
+	}
+
+	/*
+	 * As a notational convenience for callers, look through RestrictInfo.
+	 */
+	else if (IsA(node, RestrictInfo))
+	{
+		RestrictInfo *rinfo = (RestrictInfo *) node;
+
+		return max_parallel_hazard_walker((Node *) rinfo->clause, context);
+	}
+
+	/*
+	 * Really we should not see SubLink during a max_interesting == restricted
+	 * scan, but if we do, return true.
+	 */
+	else if (IsA(node, SubLink))
+	{
+		if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
+			return true;
+	}
+
+	/*
+	 * Only parallel-safe SubPlans can be sent to workers.  Within the
+	 * testexpr of the SubPlan, Params representing the output columns of the
+	 * subplan can be treated as parallel-safe, so temporarily add their IDs
+	 * to the safe_param_ids list while examining the testexpr.
+	 */
+	else if (IsA(node, SubPlan))
+	{
+		SubPlan    *subplan = (SubPlan *) node;
+		List	   *save_safe_param_ids;
+
+		if (!subplan->parallel_safe &&
+			max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
+			return true;
+		save_safe_param_ids = context->safe_param_ids;
+		context->safe_param_ids = list_concat_copy(context->safe_param_ids,
+												   subplan->paramIds);
+		if (max_parallel_hazard_walker(subplan->testexpr, context))
+			return true;		/* no need to restore safe_param_ids */
+		list_free(context->safe_param_ids);
+		context->safe_param_ids = save_safe_param_ids;
+		/* we must also check args, but no special Param treatment there */
+		if (max_parallel_hazard_walker((Node *) subplan->args, context))
+			return true;
+		/* don't want to recurse normally, so we're done */
+		return false;
+	}
+
+	/*
+	 * We can't pass Params to workers at the moment either, so they are also
+	 * parallel-restricted, unless they are PARAM_EXTERN Params or are
+	 * PARAM_EXEC Params listed in safe_param_ids, meaning they could be
+	 * either generated within workers or can be computed by the leader and
+	 * then their value can be passed to workers.
+	 */
+	else if (IsA(node, Param))
+	{
+		Param	   *param = (Param *) node;
+
+		if (param->paramkind == PARAM_EXTERN)
+			return false;
+
+		if (param->paramkind != PARAM_EXEC ||
+			!list_member_int(context->safe_param_ids, param->paramid))
+		{
+			if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
+				return true;
+		}
+		return false;			/* nothing to recurse to */
+	}
+
+	/*
+	 * When we're first invoked on a completely unplanned tree, we must
+	 * recurse into subqueries so to as to locate parallel-unsafe constructs
+	 * anywhere in the tree.
+	 */
+	else if (IsA(node, Query))
+	{
+		Query	   *query = (Query *) node;
+
+		/* SELECT FOR UPDATE/SHARE must be treated as unsafe */
+		if (query->rowMarks != NULL)
+		{
+			context->max_hazard = PROPARALLEL_UNSAFE;
+			return true;
+		}
+
+		/* Recurse into subselects */
+		return query_tree_walker(query,
+								 max_parallel_hazard_walker,
+								 context, 0);
+	}
+
+	/* Recurse to check arguments */
+	return expression_tree_walker(node,
+								  max_parallel_hazard_walker,
+								  context);
+}
+
+
+/*****************************************************************************
+ *		Check clauses for nonstrict functions
+ *****************************************************************************/
+
+/*
+ * contain_nonstrict_functions
+ *	  Recursively search for nonstrict functions within a clause.
+ *
+ * Returns true if any nonstrict construct is found --- ie, anything that
+ * could produce non-NULL output with a NULL input.
+ *
+ * The idea here is that the caller has verified that the expression contains
+ * one or more Var or Param nodes (as appropriate for the caller's need), and
+ * now wishes to prove that the expression result will be NULL if any of these
+ * inputs is NULL.  If we return false, then the proof succeeded.
+ */
+bool
+contain_nonstrict_functions(Node *clause)
+{
+	return contain_nonstrict_functions_walker(clause, NULL);
+}
+
+static bool
+contain_nonstrict_functions_checker(Oid func_id, void *context)
+{
+	return !func_strict(func_id);
+}
+
+static bool
+contain_nonstrict_functions_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Aggref))
+	{
+		/* an aggregate could return non-null with null input */
+		return true;
+	}
+	if (IsA(node, GroupingFunc))
+	{
+		/*
+		 * A GroupingFunc doesn't evaluate its arguments, and therefore must
+		 * be treated as nonstrict.
+		 */
+		return true;
+	}
+	if (IsA(node, WindowFunc))
+	{
+		/* a window function could return non-null with null input */
+		return true;
+	}
+	if (IsA(node, SubscriptingRef))
+	{
+		SubscriptingRef *sbsref = (SubscriptingRef *) node;
+		const SubscriptRoutines *sbsroutines;
+
+		/* Subscripting assignment is always presumed nonstrict */
+		if (sbsref->refassgnexpr != NULL)
+			return true;
+		/* Otherwise we must look up the subscripting support methods */
+		sbsroutines = getSubscriptingRoutines(sbsref->refcontainertype, NULL);
+		if (!(sbsroutines && sbsroutines->fetch_strict))
+			return true;
+		/* else fall through to check args */
+	}
+	if (IsA(node, DistinctExpr))
+	{
+		/* IS DISTINCT FROM is inherently non-strict */
+		return true;
+	}
+	if (IsA(node, NullIfExpr))
+	{
+		/* NULLIF is inherently non-strict */
+		return true;
+	}
+	if (IsA(node, BoolExpr))
+	{
+		BoolExpr   *expr = (BoolExpr *) node;
+
+		switch (expr->boolop)
+		{
+			case AND_EXPR:
+			case OR_EXPR:
+				/* AND, OR are inherently non-strict */
+				return true;
+			default:
+				break;
+		}
+	}
+	if (IsA(node, SubLink))
+	{
+		/* In some cases a sublink might be strict, but in general not */
+		return true;
+	}
+	if (IsA(node, SubPlan))
+		return true;
+	if (IsA(node, AlternativeSubPlan))
+		return true;
+	if (IsA(node, FieldStore))
+		return true;
+	if (IsA(node, CoerceViaIO))
+	{
+		/*
+		 * CoerceViaIO is strict regardless of whether the I/O functions are,
+		 * so just go look at its argument; asking check_functions_in_node is
+		 * useless expense and could deliver the wrong answer.
+		 */
+		return contain_nonstrict_functions_walker((Node *) ((CoerceViaIO *) node)->arg,
+												  context);
+	}
+	if (IsA(node, ArrayCoerceExpr))
+	{
+		/*
+		 * ArrayCoerceExpr is strict at the array level, regardless of what
+		 * the per-element expression is; so we should ignore elemexpr and
+		 * recurse only into the arg.
+		 */
+		return contain_nonstrict_functions_walker((Node *) ((ArrayCoerceExpr *) node)->arg,
+												  context);
+	}
+	if (IsA(node, CaseExpr))
+		return true;
+	if (IsA(node, ArrayExpr))
+		return true;
+	if (IsA(node, RowExpr))
+		return true;
+	if (IsA(node, RowCompareExpr))
+		return true;
+	if (IsA(node, CoalesceExpr))
+		return true;
+	if (IsA(node, MinMaxExpr))
+		return true;
+	if (IsA(node, XmlExpr))
+		return true;
+	if (IsA(node, NullTest))
+		return true;
+	if (IsA(node, BooleanTest))
+		return true;
+
+	/* Check other function-containing nodes */
+	if (check_functions_in_node(node, contain_nonstrict_functions_checker,
+								context))
+		return true;
+
+	return expression_tree_walker(node, contain_nonstrict_functions_walker,
+								  context);
+}
+
+/*****************************************************************************
+ *		Check clauses for Params
+ *****************************************************************************/
+
+/*
+ * contain_exec_param
+ *	  Recursively search for PARAM_EXEC Params within a clause.
+ *
+ * Returns true if the clause contains any PARAM_EXEC Param with a paramid
+ * appearing in the given list of Param IDs.  Does not descend into
+ * subqueries!
+ */
+bool
+contain_exec_param(Node *clause, List *param_ids)
+{
+	return contain_exec_param_walker(clause, param_ids);
+}
+
+static bool
+contain_exec_param_walker(Node *node, List *param_ids)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Param))
+	{
+		Param	   *p = (Param *) node;
+
+		if (p->paramkind == PARAM_EXEC &&
+			list_member_int(param_ids, p->paramid))
+			return true;
+	}
+	return expression_tree_walker(node, contain_exec_param_walker, param_ids);
+}
+
+/*****************************************************************************
+ *		Check clauses for context-dependent nodes
+ *****************************************************************************/
+
+/*
+ * contain_context_dependent_node
+ *	  Recursively search for context-dependent nodes within a clause.
+ *
+ * CaseTestExpr nodes must appear directly within the corresponding CaseExpr,
+ * not nested within another one, or they'll see the wrong test value.  If one
+ * appears "bare" in the arguments of a SQL function, then we can't inline the
+ * SQL function for fear of creating such a situation.  The same applies for
+ * CaseTestExpr used within the elemexpr of an ArrayCoerceExpr.
+ *
+ * CoerceToDomainValue would have the same issue if domain CHECK expressions
+ * could get inlined into larger expressions, but presently that's impossible.
+ * Still, it might be allowed in future, or other node types with similar
+ * issues might get invented.  So give this function a generic name, and set
+ * up the recursion state to allow multiple flag bits.
+ */
+static bool
+contain_context_dependent_node(Node *clause)
+{
+	int			flags = 0;
+
+	return contain_context_dependent_node_walker(clause, &flags);
+}
+
+#define CCDN_CASETESTEXPR_OK	0x0001	/* CaseTestExpr okay here? */
+
+static bool
+contain_context_dependent_node_walker(Node *node, int *flags)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, CaseTestExpr))
+		return !(*flags & CCDN_CASETESTEXPR_OK);
+	else if (IsA(node, CaseExpr))
+	{
+		CaseExpr   *caseexpr = (CaseExpr *) node;
+
+		/*
+		 * If this CASE doesn't have a test expression, then it doesn't create
+		 * a context in which CaseTestExprs should appear, so just fall
+		 * through and treat it as a generic expression node.
+		 */
+		if (caseexpr->arg)
+		{
+			int			save_flags = *flags;
+			bool		res;
+
+			/*
+			 * Note: in principle, we could distinguish the various sub-parts
+			 * of a CASE construct and set the flag bit only for some of them,
+			 * since we are only expecting CaseTestExprs to appear in the
+			 * "expr" subtree of the CaseWhen nodes.  But it doesn't really
+			 * seem worth any extra code.  If there are any bare CaseTestExprs
+			 * elsewhere in the CASE, something's wrong already.
+			 */
+			*flags |= CCDN_CASETESTEXPR_OK;
+			res = expression_tree_walker(node,
+										 contain_context_dependent_node_walker,
+										 (void *) flags);
+			*flags = save_flags;
+			return res;
+		}
+	}
+	else if (IsA(node, ArrayCoerceExpr))
+	{
+		ArrayCoerceExpr *ac = (ArrayCoerceExpr *) node;
+		int			save_flags;
+		bool		res;
+
+		/* Check the array expression */
+		if (contain_context_dependent_node_walker((Node *) ac->arg, flags))
+			return true;
+
+		/* Check the elemexpr, which is allowed to contain CaseTestExpr */
+		save_flags = *flags;
+		*flags |= CCDN_CASETESTEXPR_OK;
+		res = contain_context_dependent_node_walker((Node *) ac->elemexpr,
+													flags);
+		*flags = save_flags;
+		return res;
+	}
+	return expression_tree_walker(node, contain_context_dependent_node_walker,
+								  (void *) flags);
+}
+
+/*****************************************************************************
+ *		  Check clauses for Vars passed to non-leakproof functions
+ *****************************************************************************/
+
+/*
+ * contain_leaked_vars
+ *		Recursively scan a clause to discover whether it contains any Var
+ *		nodes (of the current query level) that are passed as arguments to
+ *		leaky functions.
+ *
+ * Returns true if the clause contains any non-leakproof functions that are
+ * passed Var nodes of the current query level, and which might therefore leak
+ * data.  Such clauses must be applied after any lower-level security barrier
+ * clauses.
+ */
+bool
+contain_leaked_vars(Node *clause)
+{
+	return contain_leaked_vars_walker(clause, NULL);
+}
+
+static bool
+contain_leaked_vars_checker(Oid func_id, void *context)
+{
+	return !get_func_leakproof(func_id);
+}
+
+static bool
+contain_leaked_vars_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+
+	switch (nodeTag(node))
+	{
+		case T_Var:
+		case T_Const:
+		case T_Param:
+		case T_ArrayExpr:
+		case T_FieldSelect:
+		case T_FieldStore:
+		case T_NamedArgExpr:
+		case T_BoolExpr:
+		case T_RelabelType:
+		case T_CollateExpr:
+		case T_CaseExpr:
+		case T_CaseTestExpr:
+		case T_RowExpr:
+		case T_SQLValueFunction:
+		case T_NullTest:
+		case T_BooleanTest:
+		case T_NextValueExpr:
+		case T_List:
+
+			/*
+			 * We know these node types don't contain function calls; but
+			 * something further down in the node tree might.
+			 */
+			break;
+
+		case T_FuncExpr:
+		case T_OpExpr:
+		case T_DistinctExpr:
+		case T_NullIfExpr:
+		case T_ScalarArrayOpExpr:
+		case T_CoerceViaIO:
+		case T_ArrayCoerceExpr:
+
+			/*
+			 * If node contains a leaky function call, and there's any Var
+			 * underneath it, reject.
+			 */
+			if (check_functions_in_node(node, contain_leaked_vars_checker,
+										context) &&
+				contain_var_clause(node))
+				return true;
+			break;
+
+		case T_SubscriptingRef:
+			{
+				SubscriptingRef *sbsref = (SubscriptingRef *) node;
+				const SubscriptRoutines *sbsroutines;
+
+				/* Consult the subscripting support method info */
+				sbsroutines = getSubscriptingRoutines(sbsref->refcontainertype,
+													  NULL);
+				if (!sbsroutines ||
+					!(sbsref->refassgnexpr != NULL ?
+					  sbsroutines->store_leakproof :
+					  sbsroutines->fetch_leakproof))
+				{
+					/* Node is leaky, so reject if it contains Vars */
+					if (contain_var_clause(node))
+						return true;
+				}
+			}
+			break;
+
+		case T_RowCompareExpr:
+			{
+				/*
+				 * It's worth special-casing this because a leaky comparison
+				 * function only compromises one pair of row elements, which
+				 * might not contain Vars while others do.
+				 */
+				RowCompareExpr *rcexpr = (RowCompareExpr *) node;
+				ListCell   *opid;
+				ListCell   *larg;
+				ListCell   *rarg;
+
+				forthree(opid, rcexpr->opnos,
+						 larg, rcexpr->largs,
+						 rarg, rcexpr->rargs)
+				{
+					Oid			funcid = get_opcode(lfirst_oid(opid));
+
+					if (!get_func_leakproof(funcid) &&
+						(contain_var_clause((Node *) lfirst(larg)) ||
+						 contain_var_clause((Node *) lfirst(rarg))))
+						return true;
+				}
+			}
+			break;
+
+		case T_MinMaxExpr:
+			{
+				/*
+				 * MinMaxExpr is leakproof if the comparison function it calls
+				 * is leakproof.
+				 */
+				MinMaxExpr *minmaxexpr = (MinMaxExpr *) node;
+				TypeCacheEntry *typentry;
+				bool		leakproof;
+
+				/* Look up the btree comparison function for the datatype */
+				typentry = lookup_type_cache(minmaxexpr->minmaxtype,
+											 TYPECACHE_CMP_PROC);
+				if (OidIsValid(typentry->cmp_proc))
+					leakproof = get_func_leakproof(typentry->cmp_proc);
+				else
+				{
+					/*
+					 * The executor will throw an error, but here we just
+					 * treat the missing function as leaky.
+					 */
+					leakproof = false;
+				}
+
+				if (!leakproof &&
+					contain_var_clause((Node *) minmaxexpr->args))
+					return true;
+			}
+			break;
+
+		case T_CurrentOfExpr:
+
+			/*
+			 * WHERE CURRENT OF doesn't contain leaky function calls.
+			 * Moreover, it is essential that this is considered non-leaky,
+			 * since the planner must always generate a TID scan when CURRENT
+			 * OF is present -- cf. cost_tidscan.
+			 */
+			return false;
+
+		default:
+
+			/*
+			 * If we don't recognize the node tag, assume it might be leaky.
+			 * This prevents an unexpected security hole if someone adds a new
+			 * node type that can call a function.
+			 */
+			return true;
+	}
+	return expression_tree_walker(node, contain_leaked_vars_walker,
+								  context);
+}
+
+/*
+ * find_nonnullable_rels
+ *		Determine which base rels are forced nonnullable by given clause.
+ *
+ * Returns the set of all Relids that are referenced in the clause in such
+ * a way that the clause cannot possibly return TRUE if any of these Relids
+ * is an all-NULL row.  (It is OK to err on the side of conservatism; hence
+ * the analysis here is simplistic.)
+ *
+ * The semantics here are subtly different from contain_nonstrict_functions:
+ * that function is concerned with NULL results from arbitrary expressions,
+ * but here we assume that the input is a Boolean expression, and wish to
+ * see if NULL inputs will provably cause a FALSE-or-NULL result.  We expect
+ * the expression to have been AND/OR flattened and converted to implicit-AND
+ * format.
+ *
+ * Note: this function is largely duplicative of find_nonnullable_vars().
+ * The reason not to simplify this function into a thin wrapper around
+ * find_nonnullable_vars() is that the tested conditions really are different:
+ * a clause like "t1.v1 IS NOT NULL OR t1.v2 IS NOT NULL" does not prove
+ * that either v1 or v2 can't be NULL, but it does prove that the t1 row
+ * as a whole can't be all-NULL.  Also, the behavior for PHVs is different.
+ *
+ * top_level is true while scanning top-level AND/OR structure; here, showing
+ * the result is either FALSE or NULL is good enough.  top_level is false when
+ * we have descended below a NOT or a strict function: now we must be able to
+ * prove that the subexpression goes to NULL.
+ *
+ * We don't use expression_tree_walker here because we don't want to descend
+ * through very many kinds of nodes; only the ones we can be sure are strict.
+ */
+Relids
+find_nonnullable_rels(Node *clause)
+{
+	return find_nonnullable_rels_walker(clause, true);
+}
+
+static Relids
+find_nonnullable_rels_walker(Node *node, bool top_level)
+{
+	Relids		result = NULL;
+	ListCell   *l;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varlevelsup == 0)
+			result = bms_make_singleton(var->varno);
+	}
+	else if (IsA(node, List))
+	{
+		/*
+		 * At top level, we are examining an implicit-AND list: if any of the
+		 * arms produces FALSE-or-NULL then the result is FALSE-or-NULL. If
+		 * not at top level, we are examining the arguments of a strict
+		 * function: if any of them produce NULL then the result of the
+		 * function must be NULL.  So in both cases, the set of nonnullable
+		 * rels is the union of those found in the arms, and we pass down the
+		 * top_level flag unmodified.
+		 */
+		foreach(l, (List *) node)
+		{
+			result = bms_join(result,
+							  find_nonnullable_rels_walker(lfirst(l),
+														   top_level));
+		}
+	}
+	else if (IsA(node, FuncExpr))
+	{
+		FuncExpr   *expr = (FuncExpr *) node;
+
+		if (func_strict(expr->funcid))
+			result = find_nonnullable_rels_walker((Node *) expr->args, false);
+	}
+	else if (IsA(node, OpExpr))
+	{
+		OpExpr	   *expr = (OpExpr *) node;
+
+		set_opfuncid(expr);
+		if (func_strict(expr->opfuncid))
+			result = find_nonnullable_rels_walker((Node *) expr->args, false);
+	}
+	else if (IsA(node, ScalarArrayOpExpr))
+	{
+		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
+
+		if (is_strict_saop(expr, true))
+			result = find_nonnullable_rels_walker((Node *) expr->args, false);
+	}
+	else if (IsA(node, BoolExpr))
+	{
+		BoolExpr   *expr = (BoolExpr *) node;
+
+		switch (expr->boolop)
+		{
+			case AND_EXPR:
+				/* At top level we can just recurse (to the List case) */
+				if (top_level)
+				{
+					result = find_nonnullable_rels_walker((Node *) expr->args,
+														  top_level);
+					break;
+				}
+
+				/*
+				 * Below top level, even if one arm produces NULL, the result
+				 * could be FALSE (hence not NULL).  However, if *all* the
+				 * arms produce NULL then the result is NULL, so we can take
+				 * the intersection of the sets of nonnullable rels, just as
+				 * for OR.  Fall through to share code.
+				 */
+				/* FALL THRU */
+			case OR_EXPR:
+
+				/*
+				 * OR is strict if all of its arms are, so we can take the
+				 * intersection of the sets of nonnullable rels for each arm.
+				 * This works for both values of top_level.
+				 */
+				foreach(l, expr->args)
+				{
+					Relids		subresult;
+
+					subresult = find_nonnullable_rels_walker(lfirst(l),
+															 top_level);
+					if (result == NULL) /* first subresult? */
+						result = subresult;
+					else
+						result = bms_int_members(result, subresult);
+
+					/*
+					 * If the intersection is empty, we can stop looking. This
+					 * also justifies the test for first-subresult above.
+					 */
+					if (bms_is_empty(result))
+						break;
+				}
+				break;
+			case NOT_EXPR:
+				/* NOT will return null if its arg is null */
+				result = find_nonnullable_rels_walker((Node *) expr->args,
+													  false);
+				break;
+			default:
+				elog(ERROR, "unrecognized boolop: %d", (int) expr->boolop);
+				break;
+		}
+	}
+	else if (IsA(node, RelabelType))
+	{
+		RelabelType *expr = (RelabelType *) node;
+
+		result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, CoerceViaIO))
+	{
+		/* not clear this is useful, but it can't hurt */
+		CoerceViaIO *expr = (CoerceViaIO *) node;
+
+		result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, ArrayCoerceExpr))
+	{
+		/* ArrayCoerceExpr is strict at the array level; ignore elemexpr */
+		ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
+
+		result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, ConvertRowtypeExpr))
+	{
+		/* not clear this is useful, but it can't hurt */
+		ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
+
+		result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, CollateExpr))
+	{
+		CollateExpr *expr = (CollateExpr *) node;
+
+		result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, NullTest))
+	{
+		/* IS NOT NULL can be considered strict, but only at top level */
+		NullTest   *expr = (NullTest *) node;
+
+		if (top_level && expr->nulltesttype == IS_NOT_NULL && !expr->argisrow)
+			result = find_nonnullable_rels_walker((Node *) expr->arg, false);
+	}
+	else if (IsA(node, BooleanTest))
+	{
+		/* Boolean tests that reject NULL are strict at top level */
+		BooleanTest *expr = (BooleanTest *) node;
+
+		if (top_level &&
+			(expr->booltesttype == IS_TRUE ||
+			 expr->booltesttype == IS_FALSE ||
+			 expr->booltesttype == IS_NOT_UNKNOWN))
+			result = find_nonnullable_rels_walker((Node *) expr->arg, false);
+	}
+	else if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		/*
+		 * If the contained expression forces any rels non-nullable, so does
+		 * the PHV.
+		 */
+		result = find_nonnullable_rels_walker((Node *) phv->phexpr, top_level);
+
+		/*
+		 * If the PHV's syntactic scope is exactly one rel, it will be forced
+		 * to be evaluated at that rel, and so it will behave like a Var of
+		 * that rel: if the rel's entire output goes to null, so will the PHV.
+		 * (If the syntactic scope is a join, we know that the PHV will go to
+		 * null if the whole join does; but that is AND semantics while we
+		 * need OR semantics for find_nonnullable_rels' result, so we can't do
+		 * anything with the knowledge.)
+		 */
+		if (phv->phlevelsup == 0 &&
+			bms_membership(phv->phrels) == BMS_SINGLETON)
+			result = bms_add_members(result, phv->phrels);
+	}
+	return result;
+}
+
+/*
+ * find_nonnullable_vars
+ *		Determine which Vars are forced nonnullable by given clause.
+ *
+ * Returns a list of all level-zero Vars that are referenced in the clause in
+ * such a way that the clause cannot possibly return TRUE if any of these Vars
+ * is NULL.  (It is OK to err on the side of conservatism; hence the analysis
+ * here is simplistic.)
+ *
+ * The semantics here are subtly different from contain_nonstrict_functions:
+ * that function is concerned with NULL results from arbitrary expressions,
+ * but here we assume that the input is a Boolean expression, and wish to
+ * see if NULL inputs will provably cause a FALSE-or-NULL result.  We expect
+ * the expression to have been AND/OR flattened and converted to implicit-AND
+ * format.
+ *
+ * The result is a palloc'd List, but we have not copied the member Var nodes.
+ * Also, we don't bother trying to eliminate duplicate entries.
+ *
+ * top_level is true while scanning top-level AND/OR structure; here, showing
+ * the result is either FALSE or NULL is good enough.  top_level is false when
+ * we have descended below a NOT or a strict function: now we must be able to
+ * prove that the subexpression goes to NULL.
+ *
+ * We don't use expression_tree_walker here because we don't want to descend
+ * through very many kinds of nodes; only the ones we can be sure are strict.
+ */
+List *
+find_nonnullable_vars(Node *clause)
+{
+	return find_nonnullable_vars_walker(clause, true);
+}
+
+static List *
+find_nonnullable_vars_walker(Node *node, bool top_level)
+{
+	List	   *result = NIL;
+	ListCell   *l;
+
+	if (node == NULL)
+		return NIL;
+	if (IsA(node, Var))
+	{
+		Var		   *var = (Var *) node;
+
+		if (var->varlevelsup == 0)
+			result = list_make1(var);
+	}
+	else if (IsA(node, List))
+	{
+		/*
+		 * At top level, we are examining an implicit-AND list: if any of the
+		 * arms produces FALSE-or-NULL then the result is FALSE-or-NULL. If
+		 * not at top level, we are examining the arguments of a strict
+		 * function: if any of them produce NULL then the result of the
+		 * function must be NULL.  So in both cases, the set of nonnullable
+		 * vars is the union of those found in the arms, and we pass down the
+		 * top_level flag unmodified.
+		 */
+		foreach(l, (List *) node)
+		{
+			result = list_concat(result,
+								 find_nonnullable_vars_walker(lfirst(l),
+															  top_level));
+		}
+	}
+	else if (IsA(node, FuncExpr))
+	{
+		FuncExpr   *expr = (FuncExpr *) node;
+
+		if (func_strict(expr->funcid))
+			result = find_nonnullable_vars_walker((Node *) expr->args, false);
+	}
+	else if (IsA(node, OpExpr))
+	{
+		OpExpr	   *expr = (OpExpr *) node;
+
+		set_opfuncid(expr);
+		if (func_strict(expr->opfuncid))
+			result = find_nonnullable_vars_walker((Node *) expr->args, false);
+	}
+	else if (IsA(node, ScalarArrayOpExpr))
+	{
+		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
+
+		if (is_strict_saop(expr, true))
+			result = find_nonnullable_vars_walker((Node *) expr->args, false);
+	}
+	else if (IsA(node, BoolExpr))
+	{
+		BoolExpr   *expr = (BoolExpr *) node;
+
+		switch (expr->boolop)
+		{
+			case AND_EXPR:
+				/* At top level we can just recurse (to the List case) */
+				if (top_level)
+				{
+					result = find_nonnullable_vars_walker((Node *) expr->args,
+														  top_level);
+					break;
+				}
+
+				/*
+				 * Below top level, even if one arm produces NULL, the result
+				 * could be FALSE (hence not NULL).  However, if *all* the
+				 * arms produce NULL then the result is NULL, so we can take
+				 * the intersection of the sets of nonnullable vars, just as
+				 * for OR.  Fall through to share code.
+				 */
+				/* FALL THRU */
+			case OR_EXPR:
+
+				/*
+				 * OR is strict if all of its arms are, so we can take the
+				 * intersection of the sets of nonnullable vars for each arm.
+				 * This works for both values of top_level.
+				 */
+				foreach(l, expr->args)
+				{
+					List	   *subresult;
+
+					subresult = find_nonnullable_vars_walker(lfirst(l),
+															 top_level);
+					if (result == NIL)	/* first subresult? */
+						result = subresult;
+					else
+						result = list_intersection(result, subresult);
+
+					/*
+					 * If the intersection is empty, we can stop looking. This
+					 * also justifies the test for first-subresult above.
+					 */
+					if (result == NIL)
+						break;
+				}
+				break;
+			case NOT_EXPR:
+				/* NOT will return null if its arg is null */
+				result = find_nonnullable_vars_walker((Node *) expr->args,
+													  false);
+				break;
+			default:
+				elog(ERROR, "unrecognized boolop: %d", (int) expr->boolop);
+				break;
+		}
+	}
+	else if (IsA(node, RelabelType))
+	{
+		RelabelType *expr = (RelabelType *) node;
+
+		result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, CoerceViaIO))
+	{
+		/* not clear this is useful, but it can't hurt */
+		CoerceViaIO *expr = (CoerceViaIO *) node;
+
+		result = find_nonnullable_vars_walker((Node *) expr->arg, false);
+	}
+	else if (IsA(node, ArrayCoerceExpr))
+	{
+		/* ArrayCoerceExpr is strict at the array level; ignore elemexpr */
+		ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
+
+		result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, ConvertRowtypeExpr))
+	{
+		/* not clear this is useful, but it can't hurt */
+		ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
+
+		result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, CollateExpr))
+	{
+		CollateExpr *expr = (CollateExpr *) node;
+
+		result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
+	}
+	else if (IsA(node, NullTest))
+	{
+		/* IS NOT NULL can be considered strict, but only at top level */
+		NullTest   *expr = (NullTest *) node;
+
+		if (top_level && expr->nulltesttype == IS_NOT_NULL && !expr->argisrow)
+			result = find_nonnullable_vars_walker((Node *) expr->arg, false);
+	}
+	else if (IsA(node, BooleanTest))
+	{
+		/* Boolean tests that reject NULL are strict at top level */
+		BooleanTest *expr = (BooleanTest *) node;
+
+		if (top_level &&
+			(expr->booltesttype == IS_TRUE ||
+			 expr->booltesttype == IS_FALSE ||
+			 expr->booltesttype == IS_NOT_UNKNOWN))
+			result = find_nonnullable_vars_walker((Node *) expr->arg, false);
+	}
+	else if (IsA(node, PlaceHolderVar))
+	{
+		PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+		result = find_nonnullable_vars_walker((Node *) phv->phexpr, top_level);
+	}
+	return result;
+}
+
+/*
+ * find_forced_null_vars
+ *		Determine which Vars must be NULL for the given clause to return TRUE.
+ *
+ * This is the complement of find_nonnullable_vars: find the level-zero Vars
+ * that must be NULL for the clause to return TRUE.  (It is OK to err on the
+ * side of conservatism; hence the analysis here is simplistic.  In fact,
+ * we only detect simple "var IS NULL" tests at the top level.)
+ *
+ * The result is a palloc'd List, but we have not copied the member Var nodes.
+ * Also, we don't bother trying to eliminate duplicate entries.
+ */
+List *
+find_forced_null_vars(Node *node)
+{
+	List	   *result = NIL;
+	Var		   *var;
+	ListCell   *l;
+
+	if (node == NULL)
+		return NIL;
+	/* Check single-clause cases using subroutine */
+	var = find_forced_null_var(node);
+	if (var)
+	{
+		result = list_make1(var);
+	}
+	/* Otherwise, handle AND-conditions */
+	else if (IsA(node, List))
+	{
+		/*
+		 * At top level, we are examining an implicit-AND list: if any of the
+		 * arms produces FALSE-or-NULL then the result is FALSE-or-NULL.
+		 */
+		foreach(l, (List *) node)
+		{
+			result = list_concat(result,
+								 find_forced_null_vars(lfirst(l)));
+		}
+	}
+	else if (IsA(node, BoolExpr))
+	{
+		BoolExpr   *expr = (BoolExpr *) node;
+
+		/*
+		 * We don't bother considering the OR case, because it's fairly
+		 * unlikely anyone would write "v1 IS NULL OR v1 IS NULL". Likewise,
+		 * the NOT case isn't worth expending code on.
+		 */
+		if (expr->boolop == AND_EXPR)
+		{
+			/* At top level we can just recurse (to the List case) */
+			result = find_forced_null_vars((Node *) expr->args);
+		}
+	}
+	return result;
+}
+
+/*
+ * find_forced_null_var
+ *		Return the Var forced null by the given clause, or NULL if it's
+ *		not an IS NULL-type clause.  For success, the clause must enforce
+ *		*only* nullness of the particular Var, not any other conditions.
+ *
+ * This is just the single-clause case of find_forced_null_vars(), without
+ * any allowance for AND conditions.  It's used by initsplan.c on individual
+ * qual clauses.  The reason for not just applying find_forced_null_vars()
+ * is that if an AND of an IS NULL clause with something else were to somehow
+ * survive AND/OR flattening, initsplan.c might get fooled into discarding
+ * the whole clause when only the IS NULL part of it had been proved redundant.
+ */
+Var *
+find_forced_null_var(Node *node)
+{
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, NullTest))
+	{
+		/* check for var IS NULL */
+		NullTest   *expr = (NullTest *) node;
+
+		if (expr->nulltesttype == IS_NULL && !expr->argisrow)
+		{
+			Var		   *var = (Var *) expr->arg;
+
+			if (var && IsA(var, Var) &&
+				var->varlevelsup == 0)
+				return var;
+		}
+	}
+	else if (IsA(node, BooleanTest))
+	{
+		/* var IS UNKNOWN is equivalent to var IS NULL */
+		BooleanTest *expr = (BooleanTest *) node;
+
+		if (expr->booltesttype == IS_UNKNOWN)
+		{
+			Var		   *var = (Var *) expr->arg;
+
+			if (var && IsA(var, Var) &&
+				var->varlevelsup == 0)
+				return var;
+		}
+	}
+	return NULL;
+}
+
+/*
+ * Can we treat a ScalarArrayOpExpr as strict?
+ *
+ * If "falseOK" is true, then a "false" result can be considered strict,
+ * else we need to guarantee an actual NULL result for NULL input.
+ *
+ * "foo op ALL array" is strict if the op is strict *and* we can prove
+ * that the array input isn't an empty array.  We can check that
+ * for the cases of an array constant and an ARRAY[] construct.
+ *
+ * "foo op ANY array" is strict in the falseOK sense if the op is strict.
+ * If not falseOK, the test is the same as for "foo op ALL array".
+ */
+static bool
+is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK)
+{
+	Node	   *rightop;
+
+	/* The contained operator must be strict. */
+	set_sa_opfuncid(expr);
+	if (!func_strict(expr->opfuncid))
+		return false;
+	/* If ANY and falseOK, that's all we need to check. */
+	if (expr->useOr && falseOK)
+		return true;
+	/* Else, we have to see if the array is provably non-empty. */
+	Assert(list_length(expr->args) == 2);
+	rightop = (Node *) lsecond(expr->args);
+	if (rightop && IsA(rightop, Const))
+	{
+		Datum		arraydatum = ((Const *) rightop)->constvalue;
+		bool		arrayisnull = ((Const *) rightop)->constisnull;
+		ArrayType  *arrayval;
+		int			nitems;
+
+		if (arrayisnull)
+			return false;
+		arrayval = DatumGetArrayTypeP(arraydatum);
+		nitems = ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval));
+		if (nitems > 0)
+			return true;
+	}
+	else if (rightop && IsA(rightop, ArrayExpr))
+	{
+		ArrayExpr  *arrayexpr = (ArrayExpr *) rightop;
+
+		if (arrayexpr->elements != NIL && !arrayexpr->multidims)
+			return true;
+	}
+	return false;
+}
+
+
+/*****************************************************************************
+ *		Check for "pseudo-constant" clauses
+ *****************************************************************************/
+
+/*
+ * is_pseudo_constant_clause
+ *	  Detect whether an expression is "pseudo constant", ie, it contains no
+ *	  variables of the current query level and no uses of volatile functions.
+ *	  Such an expr is not necessarily a true constant: it can still contain
+ *	  Params and outer-level Vars, not to mention functions whose results
+ *	  may vary from one statement to the next.  However, the expr's value
+ *	  will be constant over any one scan of the current query, so it can be
+ *	  used as, eg, an indexscan key.  (Actually, the condition for indexscan
+ *	  keys is weaker than this; see is_pseudo_constant_for_index().)
+ *
+ * CAUTION: this function omits to test for one very important class of
+ * not-constant expressions, namely aggregates (Aggrefs).  In current usage
+ * this is only applied to WHERE clauses and so a check for Aggrefs would be
+ * a waste of cycles; but be sure to also check contain_agg_clause() if you
+ * want to know about pseudo-constness in other contexts.  The same goes
+ * for window functions (WindowFuncs).
+ */
+bool
+is_pseudo_constant_clause(Node *clause)
+{
+	/*
+	 * We could implement this check in one recursive scan.  But since the
+	 * check for volatile functions is both moderately expensive and unlikely
+	 * to fail, it seems better to look for Vars first and only check for
+	 * volatile functions if we find no Vars.
+	 */
+	if (!contain_var_clause(clause) &&
+		!contain_volatile_functions(clause))
+		return true;
+	return false;
+}
+
+/*
+ * is_pseudo_constant_clause_relids
+ *	  Same as above, except caller already has available the var membership
+ *	  of the expression; this lets us avoid the contain_var_clause() scan.
+ */
+bool
+is_pseudo_constant_clause_relids(Node *clause, Relids relids)
+{
+	if (bms_is_empty(relids) &&
+		!contain_volatile_functions(clause))
+		return true;
+	return false;
+}
+
+
+/*****************************************************************************
+ *																			 *
+ *		General clause-manipulating routines								 *
+ *																			 *
+ *****************************************************************************/
+
+/*
+ * NumRelids
+ *		(formerly clause_relids)
+ *
+ * Returns the number of different relations referenced in 'clause'.
+ */
+int
+NumRelids(PlannerInfo *root, Node *clause)
+{
+	Relids		varnos = pull_varnos(root, clause);
+	int			result = bms_num_members(varnos);
+
+	bms_free(varnos);
+	return result;
+}
+
+/*
+ * CommuteOpExpr: commute a binary operator clause
+ *
+ * XXX the clause is destructively modified!
+ */
+void
+CommuteOpExpr(OpExpr *clause)
+{
+	Oid			opoid;
+	Node	   *temp;
+
+	/* Sanity checks: caller is at fault if these fail */
+	if (!is_opclause(clause) ||
+		list_length(clause->args) != 2)
+		elog(ERROR, "cannot commute non-binary-operator clause");
+
+	opoid = get_commutator(clause->opno);
+
+	if (!OidIsValid(opoid))
+		elog(ERROR, "could not find commutator for operator %u",
+			 clause->opno);
+
+	/*
+	 * modify the clause in-place!
+	 */
+	clause->opno = opoid;
+	clause->opfuncid = InvalidOid;
+	/* opresulttype, opretset, opcollid, inputcollid need not change */
+
+	temp = linitial(clause->args);
+	linitial(clause->args) = lsecond(clause->args);
+	lsecond(clause->args) = temp;
+}
+
+/*
+ * Helper for eval_const_expressions: check that datatype of an attribute
+ * is still what it was when the expression was parsed.  This is needed to
+ * guard against improper simplification after ALTER COLUMN TYPE.  (XXX we
+ * may well need to make similar checks elsewhere?)
+ *
+ * rowtypeid may come from a whole-row Var, and therefore it can be a domain
+ * over composite, but for this purpose we only care about checking the type
+ * of a contained field.
+ */
+static bool
+rowtype_field_matches(Oid rowtypeid, int fieldnum,
+					  Oid expectedtype, int32 expectedtypmod,
+					  Oid expectedcollation)
+{
+	TupleDesc	tupdesc;
+	Form_pg_attribute attr;
+
+	/* No issue for RECORD, since there is no way to ALTER such a type */
+	if (rowtypeid == RECORDOID)
+		return true;
+	tupdesc = lookup_rowtype_tupdesc_domain(rowtypeid, -1, false);
+	if (fieldnum <= 0 || fieldnum > tupdesc->natts)
+	{
+		ReleaseTupleDesc(tupdesc);
+		return false;
+	}
+	attr = TupleDescAttr(tupdesc, fieldnum - 1);
+	if (attr->attisdropped ||
+		attr->atttypid != expectedtype ||
+		attr->atttypmod != expectedtypmod ||
+		attr->attcollation != expectedcollation)
+	{
+		ReleaseTupleDesc(tupdesc);
+		return false;
+	}
+	ReleaseTupleDesc(tupdesc);
+	return true;
+}
+
+
+/*--------------------
+ * eval_const_expressions
+ *
+ * Reduce any recognizably constant subexpressions of the given
+ * expression tree, for example "2 + 2" => "4".  More interestingly,
+ * we can reduce certain boolean expressions even when they contain
+ * non-constant subexpressions: "x OR true" => "true" no matter what
+ * the subexpression x is.  (XXX We assume that no such subexpression
+ * will have important side-effects, which is not necessarily a good
+ * assumption in the presence of user-defined functions; do we need a
+ * pg_proc flag that prevents discarding the execution of a function?)
+ *
+ * We do understand that certain functions may deliver non-constant
+ * results even with constant inputs, "nextval()" being the classic
+ * example.  Functions that are not marked "immutable" in pg_proc
+ * will not be pre-evaluated here, although we will reduce their
+ * arguments as far as possible.
+ *
+ * Whenever a function is eliminated from the expression by means of
+ * constant-expression evaluation or inlining, we add the function to
+ * root->glob->invalItems.  This ensures the plan is known to depend on
+ * such functions, even though they aren't referenced anymore.
+ *
+ * We assume that the tree has already been type-checked and contains
+ * only operators and functions that are reasonable to try to execute.
+ *
+ * NOTE: "root" can be passed as NULL if the caller never wants to do any
+ * Param substitutions nor receive info about inlined functions.
+ *
+ * NOTE: the planner assumes that this will always flatten nested AND and
+ * OR clauses into N-argument form.  See comments in prepqual.c.
+ *
+ * NOTE: another critical effect is that any function calls that require
+ * default arguments will be expanded, and named-argument calls will be
+ * converted to positional notation.  The executor won't handle either.
+ *--------------------
+ */
+Node *
+eval_const_expressions(PlannerInfo *root, Node *node)
+{
+	eval_const_expressions_context context;
+
+	if (root)
+		context.boundParams = root->glob->boundParams;	/* bound Params */
+	else
+		context.boundParams = NULL;
+	context.root = root;		/* for inlined-function dependencies */
+	context.active_fns = NIL;	/* nothing being recursively simplified */
+	context.case_val = NULL;	/* no CASE being examined */
+	context.estimate = false;	/* safe transformations only */
+	return eval_const_expressions_mutator(node, &context);
+}
+
+#define MIN_ARRAY_SIZE_FOR_HASHED_SAOP 9
+/*--------------------
+ * convert_saop_to_hashed_saop
+ *
+ * Recursively search 'node' for ScalarArrayOpExprs and fill in the hash
+ * function for any ScalarArrayOpExpr that looks like it would be useful to
+ * evaluate using a hash table rather than a linear search.
+ *
+ * We'll use a hash table if all of the following conditions are met:
+ * 1. The 2nd argument of the array contain only Consts.
+ * 2. useOr is true.
+ * 3. There's valid hash function for both left and righthand operands and
+ *	  these hash functions are the same.
+ * 4. If the array contains enough elements for us to consider it to be
+ *	  worthwhile using a hash table rather than a linear search.
+ */
+void
+convert_saop_to_hashed_saop(Node *node)
+{
+	(void) convert_saop_to_hashed_saop_walker(node, NULL);
+}
+
+static bool
+convert_saop_to_hashed_saop_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+
+	if (IsA(node, ScalarArrayOpExpr))
+	{
+		ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) node;
+		Expr	   *arrayarg = (Expr *) lsecond(saop->args);
+		Oid			lefthashfunc;
+		Oid			righthashfunc;
+
+		if (saop->useOr && arrayarg && IsA(arrayarg, Const) &&
+			!((Const *) arrayarg)->constisnull &&
+			get_op_hash_functions(saop->opno, &lefthashfunc, &righthashfunc) &&
+			lefthashfunc == righthashfunc)
+		{
+			Datum		arrdatum = ((Const *) arrayarg)->constvalue;
+			ArrayType  *arr = (ArrayType *) DatumGetPointer(arrdatum);
+			int			nitems;
+
+			/*
+			 * Only fill in the hash functions if the array looks large enough
+			 * for it to be worth hashing instead of doing a linear search.
+			 */
+			nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
+
+			if (nitems >= MIN_ARRAY_SIZE_FOR_HASHED_SAOP)
+			{
+				/* Looks good. Fill in the hash functions */
+				saop->hashfuncid = lefthashfunc;
+			}
+			return true;
+		}
+	}
+
+	return expression_tree_walker(node, convert_saop_to_hashed_saop_walker, NULL);
+}
+
+
+/*--------------------
+ * estimate_expression_value
+ *
+ * This function attempts to estimate the value of an expression for
+ * planning purposes.  It is in essence a more aggressive version of
+ * eval_const_expressions(): we will perform constant reductions that are
+ * not necessarily 100% safe, but are reasonable for estimation purposes.
+ *
+ * Currently the extra steps that are taken in this mode are:
+ * 1. Substitute values for Params, where a bound Param value has been made
+ *	  available by the caller of planner(), even if the Param isn't marked
+ *	  constant.  This effectively means that we plan using the first supplied
+ *	  value of the Param.
+ * 2. Fold stable, as well as immutable, functions to constants.
+ * 3. Reduce PlaceHolderVar nodes to their contained expressions.
+ *--------------------
+ */
+Node *
+estimate_expression_value(PlannerInfo *root, Node *node)
+{
+	eval_const_expressions_context context;
+
+	context.boundParams = root->glob->boundParams;	/* bound Params */
+	/* we do not need to mark the plan as depending on inlined functions */
+	context.root = NULL;
+	context.active_fns = NIL;	/* nothing being recursively simplified */
+	context.case_val = NULL;	/* no CASE being examined */
+	context.estimate = true;	/* unsafe transformations OK */
+	return eval_const_expressions_mutator(node, &context);
+}
+
+/*
+ * The generic case in eval_const_expressions_mutator is to recurse using
+ * expression_tree_mutator, which will copy the given node unchanged but
+ * const-simplify its arguments (if any) as far as possible.  If the node
+ * itself does immutable processing, and each of its arguments were reduced
+ * to a Const, we can then reduce it to a Const using evaluate_expr.  (Some
+ * node types need more complicated logic; for example, a CASE expression
+ * might be reducible to a constant even if not all its subtrees are.)
+ */
+#define ece_generic_processing(node) \
+	expression_tree_mutator((Node *) (node), eval_const_expressions_mutator, \
+							(void *) context)
+
+/*
+ * Check whether all arguments of the given node were reduced to Consts.
+ * By going directly to expression_tree_walker, contain_non_const_walker
+ * is not applied to the node itself, only to its children.
+ */
+#define ece_all_arguments_const(node) \
+	(!expression_tree_walker((Node *) (node), contain_non_const_walker, NULL))
+
+/* Generic macro for applying evaluate_expr */
+#define ece_evaluate_expr(node) \
+	((Node *) evaluate_expr((Expr *) (node), \
+							exprType((Node *) (node)), \
+							exprTypmod((Node *) (node)), \
+							exprCollation((Node *) (node))))
+
+/*
+ * Recursive guts of eval_const_expressions/estimate_expression_value
+ */
+static Node *
+eval_const_expressions_mutator(Node *node,
+							   eval_const_expressions_context *context)
+{
+	if (node == NULL)
+		return NULL;
+	switch (nodeTag(node))
+	{
+		case T_Param:
+			{
+				Param	   *param = (Param *) node;
+				ParamListInfo paramLI = context->boundParams;
+
+				/* Look to see if we've been given a value for this Param */
+				if (param->paramkind == PARAM_EXTERN &&
+					paramLI != NULL &&
+					param->paramid > 0 &&
+					param->paramid <= paramLI->numParams)
+				{
+					ParamExternData *prm;
+					ParamExternData prmdata;
+
+					/*
+					 * Give hook a chance in case parameter is dynamic.  Tell
+					 * it that this fetch is speculative, so it should avoid
+					 * erroring out if parameter is unavailable.
+					 */
+					if (paramLI->paramFetch != NULL)
+						prm = paramLI->paramFetch(paramLI, param->paramid,
+												  true, &prmdata);
+					else
+						prm = &paramLI->params[param->paramid - 1];
+
+					/*
+					 * We don't just check OidIsValid, but insist that the
+					 * fetched type match the Param, just in case the hook did
+					 * something unexpected.  No need to throw an error here
+					 * though; leave that for runtime.
+					 */
+					if (OidIsValid(prm->ptype) &&
+						prm->ptype == param->paramtype)
+					{
+						/* OK to substitute parameter value? */
+						if (context->estimate ||
+							(prm->pflags & PARAM_FLAG_CONST))
+						{
+							/*
+							 * Return a Const representing the param value.
+							 * Must copy pass-by-ref datatypes, since the
+							 * Param might be in a memory context
+							 * shorter-lived than our output plan should be.
+							 */
+							int16		typLen;
+							bool		typByVal;
+							Datum		pval;
+
+							get_typlenbyval(param->paramtype,
+											&typLen, &typByVal);
+							if (prm->isnull || typByVal)
+								pval = prm->value;
+							else
+								pval = datumCopy(prm->value, typByVal, typLen);
+							return (Node *) makeConst(param->paramtype,
+													  param->paramtypmod,
+													  param->paramcollid,
+													  (int) typLen,
+													  pval,
+													  prm->isnull,
+													  typByVal);
+						}
+					}
+				}
+
+				/*
+				 * Not replaceable, so just copy the Param (no need to
+				 * recurse)
+				 */
+				return (Node *) copyObject(param);
+			}
+		case T_WindowFunc:
+			{
+				WindowFunc *expr = (WindowFunc *) node;
+				Oid			funcid = expr->winfnoid;
+				List	   *args;
+				Expr	   *aggfilter;
+				HeapTuple	func_tuple;
+				WindowFunc *newexpr;
+
+				/*
+				 * We can't really simplify a WindowFunc node, but we mustn't
+				 * just fall through to the default processing, because we
+				 * have to apply expand_function_arguments to its argument
+				 * list.  That takes care of inserting default arguments and
+				 * expanding named-argument notation.
+				 */
+				func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+				if (!HeapTupleIsValid(func_tuple))
+					elog(ERROR, "cache lookup failed for function %u", funcid);
+
+				args = expand_function_arguments(expr->args,
+												 false, expr->wintype,
+												 func_tuple);
+
+				ReleaseSysCache(func_tuple);
+
+				/* Now, recursively simplify the args (which are a List) */
+				args = (List *)
+					expression_tree_mutator((Node *) args,
+											eval_const_expressions_mutator,
+											(void *) context);
+				/* ... and the filter expression, which isn't */
+				aggfilter = (Expr *)
+					eval_const_expressions_mutator((Node *) expr->aggfilter,
+												   context);
+
+				/* And build the replacement WindowFunc node */
+				newexpr = makeNode(WindowFunc);
+				newexpr->winfnoid = expr->winfnoid;
+				newexpr->wintype = expr->wintype;
+				newexpr->wincollid = expr->wincollid;
+				newexpr->inputcollid = expr->inputcollid;
+				newexpr->args = args;
+				newexpr->aggfilter = aggfilter;
+				newexpr->winref = expr->winref;
+				newexpr->winstar = expr->winstar;
+				newexpr->winagg = expr->winagg;
+				newexpr->location = expr->location;
+
+				return (Node *) newexpr;
+			}
+		case T_FuncExpr:
+			{
+				FuncExpr   *expr = (FuncExpr *) node;
+				List	   *args = expr->args;
+				Expr	   *simple;
+				FuncExpr   *newexpr;
+
+				/*
+				 * Code for op/func reduction is pretty bulky, so split it out
+				 * as a separate function.  Note: exprTypmod normally returns
+				 * -1 for a FuncExpr, but not when the node is recognizably a
+				 * length coercion; we want to preserve the typmod in the
+				 * eventual Const if so.
+				 */
+				simple = simplify_function(expr->funcid,
+										   expr->funcresulttype,
+										   exprTypmod(node),
+										   expr->funccollid,
+										   expr->inputcollid,
+										   &args,
+										   expr->funcvariadic,
+										   true,
+										   true,
+										   context);
+				if (simple)		/* successfully simplified it */
+					return (Node *) simple;
+
+				/*
+				 * The expression cannot be simplified any further, so build
+				 * and return a replacement FuncExpr node using the
+				 * possibly-simplified arguments.  Note that we have also
+				 * converted the argument list to positional notation.
+				 */
+				newexpr = makeNode(FuncExpr);
+				newexpr->funcid = expr->funcid;
+				newexpr->funcresulttype = expr->funcresulttype;
+				newexpr->funcretset = expr->funcretset;
+				newexpr->funcvariadic = expr->funcvariadic;
+				newexpr->funcformat = expr->funcformat;
+				newexpr->funccollid = expr->funccollid;
+				newexpr->inputcollid = expr->inputcollid;
+				newexpr->args = args;
+				newexpr->location = expr->location;
+				return (Node *) newexpr;
+			}
+		case T_OpExpr:
+			{
+				OpExpr	   *expr = (OpExpr *) node;
+				List	   *args = expr->args;
+				Expr	   *simple;
+				OpExpr	   *newexpr;
+
+				/*
+				 * Need to get OID of underlying function.  Okay to scribble
+				 * on input to this extent.
+				 */
+				set_opfuncid(expr);
+
+				/*
+				 * Code for op/func reduction is pretty bulky, so split it out
+				 * as a separate function.
+				 */
+				simple = simplify_function(expr->opfuncid,
+										   expr->opresulttype, -1,
+										   expr->opcollid,
+										   expr->inputcollid,
+										   &args,
+										   false,
+										   true,
+										   true,
+										   context);
+				if (simple)		/* successfully simplified it */
+					return (Node *) simple;
+
+				/*
+				 * If the operator is boolean equality or inequality, we know
+				 * how to simplify cases involving one constant and one
+				 * non-constant argument.
+				 */
+				if (expr->opno == BooleanEqualOperator ||
+					expr->opno == BooleanNotEqualOperator)
+				{
+					simple = (Expr *) simplify_boolean_equality(expr->opno,
+																args);
+					if (simple) /* successfully simplified it */
+						return (Node *) simple;
+				}
+
+				/*
+				 * The expression cannot be simplified any further, so build
+				 * and return a replacement OpExpr node using the
+				 * possibly-simplified arguments.
+				 */
+				newexpr = makeNode(OpExpr);
+				newexpr->opno = expr->opno;
+				newexpr->opfuncid = expr->opfuncid;
+				newexpr->opresulttype = expr->opresulttype;
+				newexpr->opretset = expr->opretset;
+				newexpr->opcollid = expr->opcollid;
+				newexpr->inputcollid = expr->inputcollid;
+				newexpr->args = args;
+				newexpr->location = expr->location;
+				return (Node *) newexpr;
+			}
+		case T_DistinctExpr:
+			{
+				DistinctExpr *expr = (DistinctExpr *) node;
+				List	   *args;
+				ListCell   *arg;
+				bool		has_null_input = false;
+				bool		all_null_input = true;
+				bool		has_nonconst_input = false;
+				Expr	   *simple;
+				DistinctExpr *newexpr;
+
+				/*
+				 * Reduce constants in the DistinctExpr's arguments.  We know
+				 * args is either NIL or a List node, so we can call
+				 * expression_tree_mutator directly rather than recursing to
+				 * self.
+				 */
+				args = (List *) expression_tree_mutator((Node *) expr->args,
+														eval_const_expressions_mutator,
+														(void *) context);
+
+				/*
+				 * We must do our own check for NULLs because DistinctExpr has
+				 * different results for NULL input than the underlying
+				 * operator does.
+				 */
+				foreach(arg, args)
+				{
+					if (IsA(lfirst(arg), Const))
+					{
+						has_null_input |= ((Const *) lfirst(arg))->constisnull;
+						all_null_input &= ((Const *) lfirst(arg))->constisnull;
+					}
+					else
+						has_nonconst_input = true;
+				}
+
+				/* all constants? then can optimize this out */
+				if (!has_nonconst_input)
+				{
+					/* all nulls? then not distinct */
+					if (all_null_input)
+						return makeBoolConst(false, false);
+
+					/* one null? then distinct */
+					if (has_null_input)
+						return makeBoolConst(true, false);
+
+					/* otherwise try to evaluate the '=' operator */
+					/* (NOT okay to try to inline it, though!) */
+
+					/*
+					 * Need to get OID of underlying function.  Okay to
+					 * scribble on input to this extent.
+					 */
+					set_opfuncid((OpExpr *) expr);	/* rely on struct
+													 * equivalence */
+
+					/*
+					 * Code for op/func reduction is pretty bulky, so split it
+					 * out as a separate function.
+					 */
+					simple = simplify_function(expr->opfuncid,
+											   expr->opresulttype, -1,
+											   expr->opcollid,
+											   expr->inputcollid,
+											   &args,
+											   false,
+											   false,
+											   false,
+											   context);
+					if (simple) /* successfully simplified it */
+					{
+						/*
+						 * Since the underlying operator is "=", must negate
+						 * its result
+						 */
+						Const	   *csimple = castNode(Const, simple);
+
+						csimple->constvalue =
+							BoolGetDatum(!DatumGetBool(csimple->constvalue));
+						return (Node *) csimple;
+					}
+				}
+
+				/*
+				 * The expression cannot be simplified any further, so build
+				 * and return a replacement DistinctExpr node using the
+				 * possibly-simplified arguments.
+				 */
+				newexpr = makeNode(DistinctExpr);
+				newexpr->opno = expr->opno;
+				newexpr->opfuncid = expr->opfuncid;
+				newexpr->opresulttype = expr->opresulttype;
+				newexpr->opretset = expr->opretset;
+				newexpr->opcollid = expr->opcollid;
+				newexpr->inputcollid = expr->inputcollid;
+				newexpr->args = args;
+				newexpr->location = expr->location;
+				return (Node *) newexpr;
+			}
+		case T_NullIfExpr:
+			{
+				NullIfExpr *expr;
+				ListCell   *arg;
+				bool		has_nonconst_input = false;
+
+				/* Copy the node and const-simplify its arguments */
+				expr = (NullIfExpr *) ece_generic_processing(node);
+
+				/* If either argument is NULL they can't be equal */
+				foreach(arg, expr->args)
+				{
+					if (!IsA(lfirst(arg), Const))
+						has_nonconst_input = true;
+					else if (((Const *) lfirst(arg))->constisnull)
+						return (Node *) linitial(expr->args);
+				}
+
+				/*
+				 * Need to get OID of underlying function before checking if
+				 * the function is OK to evaluate.
+				 */
+				set_opfuncid((OpExpr *) expr);
+
+				if (!has_nonconst_input &&
+					ece_function_is_safe(expr->opfuncid, context))
+					return ece_evaluate_expr(expr);
+
+				return (Node *) expr;
+			}
+		case T_ScalarArrayOpExpr:
+			{
+				ScalarArrayOpExpr *saop;
+
+				/* Copy the node and const-simplify its arguments */
+				saop = (ScalarArrayOpExpr *) ece_generic_processing(node);
+
+				/* Make sure we know underlying function */
+				set_sa_opfuncid(saop);
+
+				/*
+				 * If all arguments are Consts, and it's a safe function, we
+				 * can fold to a constant
+				 */
+				if (ece_all_arguments_const(saop) &&
+					ece_function_is_safe(saop->opfuncid, context))
+					return ece_evaluate_expr(saop);
+				return (Node *) saop;
+			}
+		case T_BoolExpr:
+			{
+				BoolExpr   *expr = (BoolExpr *) node;
+
+				switch (expr->boolop)
+				{
+					case OR_EXPR:
+						{
+							List	   *newargs;
+							bool		haveNull = false;
+							bool		forceTrue = false;
+
+							newargs = simplify_or_arguments(expr->args,
+															context,
+															&haveNull,
+															&forceTrue);
+							if (forceTrue)
+								return makeBoolConst(true, false);
+							if (haveNull)
+								newargs = lappend(newargs,
+												  makeBoolConst(false, true));
+							/* If all the inputs are FALSE, result is FALSE */
+							if (newargs == NIL)
+								return makeBoolConst(false, false);
+
+							/*
+							 * If only one nonconst-or-NULL input, it's the
+							 * result
+							 */
+							if (list_length(newargs) == 1)
+								return (Node *) linitial(newargs);
+							/* Else we still need an OR node */
+							return (Node *) make_orclause(newargs);
+						}
+					case AND_EXPR:
+						{
+							List	   *newargs;
+							bool		haveNull = false;
+							bool		forceFalse = false;
+
+							newargs = simplify_and_arguments(expr->args,
+															 context,
+															 &haveNull,
+															 &forceFalse);
+							if (forceFalse)
+								return makeBoolConst(false, false);
+							if (haveNull)
+								newargs = lappend(newargs,
+												  makeBoolConst(false, true));
+							/* If all the inputs are TRUE, result is TRUE */
+							if (newargs == NIL)
+								return makeBoolConst(true, false);
+
+							/*
+							 * If only one nonconst-or-NULL input, it's the
+							 * result
+							 */
+							if (list_length(newargs) == 1)
+								return (Node *) linitial(newargs);
+							/* Else we still need an AND node */
+							return (Node *) make_andclause(newargs);
+						}
+					case NOT_EXPR:
+						{
+							Node	   *arg;
+
+							Assert(list_length(expr->args) == 1);
+							arg = eval_const_expressions_mutator(linitial(expr->args),
+																 context);
+
+							/*
+							 * Use negate_clause() to see if we can simplify
+							 * away the NOT.
+							 */
+							return negate_clause(arg);
+						}
+					default:
+						elog(ERROR, "unrecognized boolop: %d",
+							 (int) expr->boolop);
+						break;
+				}
+				break;
+			}
+		case T_SubPlan:
+		case T_AlternativeSubPlan:
+
+			/*
+			 * Return a SubPlan unchanged --- too late to do anything with it.
+			 *
+			 * XXX should we ereport() here instead?  Probably this routine
+			 * should never be invoked after SubPlan creation.
+			 */
+			return node;
+		case T_RelabelType:
+			{
+				RelabelType *relabel = (RelabelType *) node;
+				Node	   *arg;
+
+				/* Simplify the input ... */
+				arg = eval_const_expressions_mutator((Node *) relabel->arg,
+													 context);
+				/* ... and attach a new RelabelType node, if needed */
+				return applyRelabelType(arg,
+										relabel->resulttype,
+										relabel->resulttypmod,
+										relabel->resultcollid,
+										relabel->relabelformat,
+										relabel->location,
+										true);
+			}
+		case T_CoerceViaIO:
+			{
+				CoerceViaIO *expr = (CoerceViaIO *) node;
+				List	   *args;
+				Oid			outfunc;
+				bool		outtypisvarlena;
+				Oid			infunc;
+				Oid			intypioparam;
+				Expr	   *simple;
+				CoerceViaIO *newexpr;
+
+				/* Make a List so we can use simplify_function */
+				args = list_make1(expr->arg);
+
+				/*
+				 * CoerceViaIO represents calling the source type's output
+				 * function then the result type's input function.  So, try to
+				 * simplify it as though it were a stack of two such function
+				 * calls.  First we need to know what the functions are.
+				 *
+				 * Note that the coercion functions are assumed not to care
+				 * about input collation, so we just pass InvalidOid for that.
+				 */
+				getTypeOutputInfo(exprType((Node *) expr->arg),
+								  &outfunc, &outtypisvarlena);
+				getTypeInputInfo(expr->resulttype,
+								 &infunc, &intypioparam);
+
+				simple = simplify_function(outfunc,
+										   CSTRINGOID, -1,
+										   InvalidOid,
+										   InvalidOid,
+										   &args,
+										   false,
+										   true,
+										   true,
+										   context);
+				if (simple)		/* successfully simplified output fn */
+				{
+					/*
+					 * Input functions may want 1 to 3 arguments.  We always
+					 * supply all three, trusting that nothing downstream will
+					 * complain.
+					 */
+					args = list_make3(simple,
+									  makeConst(OIDOID,
+												-1,
+												InvalidOid,
+												sizeof(Oid),
+												ObjectIdGetDatum(intypioparam),
+												false,
+												true),
+									  makeConst(INT4OID,
+												-1,
+												InvalidOid,
+												sizeof(int32),
+												Int32GetDatum(-1),
+												false,
+												true));
+
+					simple = simplify_function(infunc,
+											   expr->resulttype, -1,
+											   expr->resultcollid,
+											   InvalidOid,
+											   &args,
+											   false,
+											   false,
+											   true,
+											   context);
+					if (simple) /* successfully simplified input fn */
+						return (Node *) simple;
+				}
+
+				/*
+				 * The expression cannot be simplified any further, so build
+				 * and return a replacement CoerceViaIO node using the
+				 * possibly-simplified argument.
+				 */
+				newexpr = makeNode(CoerceViaIO);
+				newexpr->arg = (Expr *) linitial(args);
+				newexpr->resulttype = expr->resulttype;
+				newexpr->resultcollid = expr->resultcollid;
+				newexpr->coerceformat = expr->coerceformat;
+				newexpr->location = expr->location;
+				return (Node *) newexpr;
+			}
+		case T_ArrayCoerceExpr:
+			{
+				ArrayCoerceExpr *ac = makeNode(ArrayCoerceExpr);
+				Node	   *save_case_val;
+
+				/*
+				 * Copy the node and const-simplify its arguments.  We can't
+				 * use ece_generic_processing() here because we need to mess
+				 * with case_val only while processing the elemexpr.
+				 */
+				memcpy(ac, node, sizeof(ArrayCoerceExpr));
+				ac->arg = (Expr *)
+					eval_const_expressions_mutator((Node *) ac->arg,
+												   context);
+
+				/*
+				 * Set up for the CaseTestExpr node contained in the elemexpr.
+				 * We must prevent it from absorbing any outer CASE value.
+				 */
+				save_case_val = context->case_val;
+				context->case_val = NULL;
+
+				ac->elemexpr = (Expr *)
+					eval_const_expressions_mutator((Node *) ac->elemexpr,
+												   context);
+
+				context->case_val = save_case_val;
+
+				/*
+				 * If constant argument and the per-element expression is
+				 * immutable, we can simplify the whole thing to a constant.
+				 * Exception: although contain_mutable_functions considers
+				 * CoerceToDomain immutable for historical reasons, let's not
+				 * do so here; this ensures coercion to an array-over-domain
+				 * does not apply the domain's constraints until runtime.
+				 */
+				if (ac->arg && IsA(ac->arg, Const) &&
+					ac->elemexpr && !IsA(ac->elemexpr, CoerceToDomain) &&
+					!contain_mutable_functions((Node *) ac->elemexpr))
+					return ece_evaluate_expr(ac);
+
+				return (Node *) ac;
+			}
+		case T_CollateExpr:
+			{
+				/*
+				 * We replace CollateExpr with RelabelType, so as to improve
+				 * uniformity of expression representation and thus simplify
+				 * comparison of expressions.  Hence this looks very nearly
+				 * the same as the RelabelType case, and we can apply the same
+				 * optimizations to avoid unnecessary RelabelTypes.
+				 */
+				CollateExpr *collate = (CollateExpr *) node;
+				Node	   *arg;
+
+				/* Simplify the input ... */
+				arg = eval_const_expressions_mutator((Node *) collate->arg,
+													 context);
+				/* ... and attach a new RelabelType node, if needed */
+				return applyRelabelType(arg,
+										exprType(arg),
+										exprTypmod(arg),
+										collate->collOid,
+										COERCE_IMPLICIT_CAST,
+										collate->location,
+										true);
+			}
+		case T_CaseExpr:
+			{
+				/*----------
+				 * CASE expressions can be simplified if there are constant
+				 * condition clauses:
+				 *		FALSE (or NULL): drop the alternative
+				 *		TRUE: drop all remaining alternatives
+				 * If the first non-FALSE alternative is a constant TRUE,
+				 * we can simplify the entire CASE to that alternative's
+				 * expression.  If there are no non-FALSE alternatives,
+				 * we simplify the entire CASE to the default result (ELSE).
+				 *
+				 * If we have a simple-form CASE with constant test
+				 * expression, we substitute the constant value for contained
+				 * CaseTestExpr placeholder nodes, so that we have the
+				 * opportunity to reduce constant test conditions.  For
+				 * example this allows
+				 *		CASE 0 WHEN 0 THEN 1 ELSE 1/0 END
+				 * to reduce to 1 rather than drawing a divide-by-0 error.
+				 * Note that when the test expression is constant, we don't
+				 * have to include it in the resulting CASE; for example
+				 *		CASE 0 WHEN x THEN y ELSE z END
+				 * is transformed by the parser to
+				 *		CASE 0 WHEN CaseTestExpr = x THEN y ELSE z END
+				 * which we can simplify to
+				 *		CASE WHEN 0 = x THEN y ELSE z END
+				 * It is not necessary for the executor to evaluate the "arg"
+				 * expression when executing the CASE, since any contained
+				 * CaseTestExprs that might have referred to it will have been
+				 * replaced by the constant.
+				 *----------
+				 */
+				CaseExpr   *caseexpr = (CaseExpr *) node;
+				CaseExpr   *newcase;
+				Node	   *save_case_val;
+				Node	   *newarg;
+				List	   *newargs;
+				bool		const_true_cond;
+				Node	   *defresult = NULL;
+				ListCell   *arg;
+
+				/* Simplify the test expression, if any */
+				newarg = eval_const_expressions_mutator((Node *) caseexpr->arg,
+														context);
+
+				/* Set up for contained CaseTestExpr nodes */
+				save_case_val = context->case_val;
+				if (newarg && IsA(newarg, Const))
+				{
+					context->case_val = newarg;
+					newarg = NULL;	/* not needed anymore, see above */
+				}
+				else
+					context->case_val = NULL;
+
+				/* Simplify the WHEN clauses */
+				newargs = NIL;
+				const_true_cond = false;
+				foreach(arg, caseexpr->args)
+				{
+					CaseWhen   *oldcasewhen = lfirst_node(CaseWhen, arg);
+					Node	   *casecond;
+					Node	   *caseresult;
+
+					/* Simplify this alternative's test condition */
+					casecond = eval_const_expressions_mutator((Node *) oldcasewhen->expr,
+															  context);
+
+					/*
+					 * If the test condition is constant FALSE (or NULL), then
+					 * drop this WHEN clause completely, without processing
+					 * the result.
+					 */
+					if (casecond && IsA(casecond, Const))
+					{
+						Const	   *const_input = (Const *) casecond;
+
+						if (const_input->constisnull ||
+							!DatumGetBool(const_input->constvalue))
+							continue;	/* drop alternative with FALSE cond */
+						/* Else it's constant TRUE */
+						const_true_cond = true;
+					}
+
+					/* Simplify this alternative's result value */
+					caseresult = eval_const_expressions_mutator((Node *) oldcasewhen->result,
+																context);
+
+					/* If non-constant test condition, emit a new WHEN node */
+					if (!const_true_cond)
+					{
+						CaseWhen   *newcasewhen = makeNode(CaseWhen);
+
+						newcasewhen->expr = (Expr *) casecond;
+						newcasewhen->result = (Expr *) caseresult;
+						newcasewhen->location = oldcasewhen->location;
+						newargs = lappend(newargs, newcasewhen);
+						continue;
+					}
+
+					/*
+					 * Found a TRUE condition, so none of the remaining
+					 * alternatives can be reached.  We treat the result as
+					 * the default result.
+					 */
+					defresult = caseresult;
+					break;
+				}
+
+				/* Simplify the default result, unless we replaced it above */
+				if (!const_true_cond)
+					defresult = eval_const_expressions_mutator((Node *) caseexpr->defresult,
+															   context);
+
+				context->case_val = save_case_val;
+
+				/*
+				 * If no non-FALSE alternatives, CASE reduces to the default
+				 * result
+				 */
+				if (newargs == NIL)
+					return defresult;
+				/* Otherwise we need a new CASE node */
+				newcase = makeNode(CaseExpr);
+				newcase->casetype = caseexpr->casetype;
+				newcase->casecollid = caseexpr->casecollid;
+				newcase->arg = (Expr *) newarg;
+				newcase->args = newargs;
+				newcase->defresult = (Expr *) defresult;
+				newcase->location = caseexpr->location;
+				return (Node *) newcase;
+			}
+		case T_CaseTestExpr:
+			{
+				/*
+				 * If we know a constant test value for the current CASE
+				 * construct, substitute it for the placeholder.  Else just
+				 * return the placeholder as-is.
+				 */
+				if (context->case_val)
+					return copyObject(context->case_val);
+				else
+					return copyObject(node);
+			}
+		case T_SubscriptingRef:
+		case T_ArrayExpr:
+		case T_RowExpr:
+		case T_MinMaxExpr:
+			{
+				/*
+				 * Generic handling for node types whose own processing is
+				 * known to be immutable, and for which we need no smarts
+				 * beyond "simplify if all inputs are constants".
+				 *
+				 * Treating SubscriptingRef this way assumes that subscripting
+				 * fetch and assignment are both immutable.  This constrains
+				 * type-specific subscripting implementations; maybe we should
+				 * relax it someday.
+				 *
+				 * Treating MinMaxExpr this way amounts to assuming that the
+				 * btree comparison function it calls is immutable; see the
+				 * reasoning in contain_mutable_functions_walker.
+				 */
+
+				/* Copy the node and const-simplify its arguments */
+				node = ece_generic_processing(node);
+				/* If all arguments are Consts, we can fold to a constant */
+				if (ece_all_arguments_const(node))
+					return ece_evaluate_expr(node);
+				return node;
+			}
+		case T_CoalesceExpr:
+			{
+				CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
+				CoalesceExpr *newcoalesce;
+				List	   *newargs;
+				ListCell   *arg;
+
+				newargs = NIL;
+				foreach(arg, coalesceexpr->args)
+				{
+					Node	   *e;
+
+					e = eval_const_expressions_mutator((Node *) lfirst(arg),
+													   context);
+
+					/*
+					 * We can remove null constants from the list. For a
+					 * non-null constant, if it has not been preceded by any
+					 * other non-null-constant expressions then it is the
+					 * result. Otherwise, it's the next argument, but we can
+					 * drop following arguments since they will never be
+					 * reached.
+					 */
+					if (IsA(e, Const))
+					{
+						if (((Const *) e)->constisnull)
+							continue;	/* drop null constant */
+						if (newargs == NIL)
+							return e;	/* first expr */
+						newargs = lappend(newargs, e);
+						break;
+					}
+					newargs = lappend(newargs, e);
+				}
+
+				/*
+				 * If all the arguments were constant null, the result is just
+				 * null
+				 */
+				if (newargs == NIL)
+					return (Node *) makeNullConst(coalesceexpr->coalescetype,
+												  -1,
+												  coalesceexpr->coalescecollid);
+
+				newcoalesce = makeNode(CoalesceExpr);
+				newcoalesce->coalescetype = coalesceexpr->coalescetype;
+				newcoalesce->coalescecollid = coalesceexpr->coalescecollid;
+				newcoalesce->args = newargs;
+				newcoalesce->location = coalesceexpr->location;
+				return (Node *) newcoalesce;
+			}
+		case T_SQLValueFunction:
+			{
+				/*
+				 * All variants of SQLValueFunction are stable, so if we are
+				 * estimating the expression's value, we should evaluate the
+				 * current function value.  Otherwise just copy.
+				 */
+				SQLValueFunction *svf = (SQLValueFunction *) node;
+
+				if (context->estimate)
+					return (Node *) evaluate_expr((Expr *) svf,
+												  svf->type,
+												  svf->typmod,
+												  InvalidOid);
+				else
+					return copyObject((Node *) svf);
+			}
+		case T_FieldSelect:
+			{
+				/*
+				 * We can optimize field selection from a whole-row Var into a
+				 * simple Var.  (This case won't be generated directly by the
+				 * parser, because ParseComplexProjection short-circuits it.
+				 * But it can arise while simplifying functions.)  Also, we
+				 * can optimize field selection from a RowExpr construct, or
+				 * of course from a constant.
+				 *
+				 * However, replacing a whole-row Var in this way has a
+				 * pitfall: if we've already built the rel targetlist for the
+				 * source relation, then the whole-row Var is scheduled to be
+				 * produced by the relation scan, but the simple Var probably
+				 * isn't, which will lead to a failure in setrefs.c.  This is
+				 * not a problem when handling simple single-level queries, in
+				 * which expression simplification always happens first.  It
+				 * is a risk for lateral references from subqueries, though.
+				 * To avoid such failures, don't optimize uplevel references.
+				 *
+				 * We must also check that the declared type of the field is
+				 * still the same as when the FieldSelect was created --- this
+				 * can change if someone did ALTER COLUMN TYPE on the rowtype.
+				 * If it isn't, we skip the optimization; the case will
+				 * probably fail at runtime, but that's not our problem here.
+				 */
+				FieldSelect *fselect = (FieldSelect *) node;
+				FieldSelect *newfselect;
+				Node	   *arg;
+
+				arg = eval_const_expressions_mutator((Node *) fselect->arg,
+													 context);
+				if (arg && IsA(arg, Var) &&
+					((Var *) arg)->varattno == InvalidAttrNumber &&
+					((Var *) arg)->varlevelsup == 0)
+				{
+					if (rowtype_field_matches(((Var *) arg)->vartype,
+											  fselect->fieldnum,
+											  fselect->resulttype,
+											  fselect->resulttypmod,
+											  fselect->resultcollid))
+						return (Node *) makeVar(((Var *) arg)->varno,
+												fselect->fieldnum,
+												fselect->resulttype,
+												fselect->resulttypmod,
+												fselect->resultcollid,
+												((Var *) arg)->varlevelsup);
+				}
+				if (arg && IsA(arg, RowExpr))
+				{
+					RowExpr    *rowexpr = (RowExpr *) arg;
+
+					if (fselect->fieldnum > 0 &&
+						fselect->fieldnum <= list_length(rowexpr->args))
+					{
+						Node	   *fld = (Node *) list_nth(rowexpr->args,
+															fselect->fieldnum - 1);
+
+						if (rowtype_field_matches(rowexpr->row_typeid,
+												  fselect->fieldnum,
+												  fselect->resulttype,
+												  fselect->resulttypmod,
+												  fselect->resultcollid) &&
+							fselect->resulttype == exprType(fld) &&
+							fselect->resulttypmod == exprTypmod(fld) &&
+							fselect->resultcollid == exprCollation(fld))
+							return fld;
+					}
+				}
+				newfselect = makeNode(FieldSelect);
+				newfselect->arg = (Expr *) arg;
+				newfselect->fieldnum = fselect->fieldnum;
+				newfselect->resulttype = fselect->resulttype;
+				newfselect->resulttypmod = fselect->resulttypmod;
+				newfselect->resultcollid = fselect->resultcollid;
+				if (arg && IsA(arg, Const))
+				{
+					Const	   *con = (Const *) arg;
+
+					if (rowtype_field_matches(con->consttype,
+											  newfselect->fieldnum,
+											  newfselect->resulttype,
+											  newfselect->resulttypmod,
+											  newfselect->resultcollid))
+						return ece_evaluate_expr(newfselect);
+				}
+				return (Node *) newfselect;
+			}
+		case T_NullTest:
+			{
+				NullTest   *ntest = (NullTest *) node;
+				NullTest   *newntest;
+				Node	   *arg;
+
+				arg = eval_const_expressions_mutator((Node *) ntest->arg,
+													 context);
+				if (ntest->argisrow && arg && IsA(arg, RowExpr))
+				{
+					/*
+					 * We break ROW(...) IS [NOT] NULL into separate tests on
+					 * its component fields.  This form is usually more
+					 * efficient to evaluate, as well as being more amenable
+					 * to optimization.
+					 */
+					RowExpr    *rarg = (RowExpr *) arg;
+					List	   *newargs = NIL;
+					ListCell   *l;
+
+					foreach(l, rarg->args)
+					{
+						Node	   *relem = (Node *) lfirst(l);
+
+						/*
+						 * A constant field refutes the whole NullTest if it's
+						 * of the wrong nullness; else we can discard it.
+						 */
+						if (relem && IsA(relem, Const))
+						{
+							Const	   *carg = (Const *) relem;
+
+							if (carg->constisnull ?
+								(ntest->nulltesttype == IS_NOT_NULL) :
+								(ntest->nulltesttype == IS_NULL))
+								return makeBoolConst(false, false);
+							continue;
+						}
+
+						/*
+						 * Else, make a scalar (argisrow == false) NullTest
+						 * for this field.  Scalar semantics are required
+						 * because IS [NOT] NULL doesn't recurse; see comments
+						 * in ExecEvalRowNullInt().
+						 */
+						newntest = makeNode(NullTest);
+						newntest->arg = (Expr *) relem;
+						newntest->nulltesttype = ntest->nulltesttype;
+						newntest->argisrow = false;
+						newntest->location = ntest->location;
+						newargs = lappend(newargs, newntest);
+					}
+					/* If all the inputs were constants, result is TRUE */
+					if (newargs == NIL)
+						return makeBoolConst(true, false);
+					/* If only one nonconst input, it's the result */
+					if (list_length(newargs) == 1)
+						return (Node *) linitial(newargs);
+					/* Else we need an AND node */
+					return (Node *) make_andclause(newargs);
+				}
+				if (!ntest->argisrow && arg && IsA(arg, Const))
+				{
+					Const	   *carg = (Const *) arg;
+					bool		result;
+
+					switch (ntest->nulltesttype)
+					{
+						case IS_NULL:
+							result = carg->constisnull;
+							break;
+						case IS_NOT_NULL:
+							result = !carg->constisnull;
+							break;
+						default:
+							elog(ERROR, "unrecognized nulltesttype: %d",
+								 (int) ntest->nulltesttype);
+							result = false; /* keep compiler quiet */
+							break;
+					}
+
+					return makeBoolConst(result, false);
+				}
+
+				newntest = makeNode(NullTest);
+				newntest->arg = (Expr *) arg;
+				newntest->nulltesttype = ntest->nulltesttype;
+				newntest->argisrow = ntest->argisrow;
+				newntest->location = ntest->location;
+				return (Node *) newntest;
+			}
+		case T_BooleanTest:
+			{
+				/*
+				 * This case could be folded into the generic handling used
+				 * for ArrayExpr etc.  But because the simplification logic is
+				 * so trivial, applying evaluate_expr() to perform it would be
+				 * a heavy overhead.  BooleanTest is probably common enough to
+				 * justify keeping this bespoke implementation.
+				 */
+				BooleanTest *btest = (BooleanTest *) node;
+				BooleanTest *newbtest;
+				Node	   *arg;
+
+				arg = eval_const_expressions_mutator((Node *) btest->arg,
+													 context);
+				if (arg && IsA(arg, Const))
+				{
+					Const	   *carg = (Const *) arg;
+					bool		result;
+
+					switch (btest->booltesttype)
+					{
+						case IS_TRUE:
+							result = (!carg->constisnull &&
+									  DatumGetBool(carg->constvalue));
+							break;
+						case IS_NOT_TRUE:
+							result = (carg->constisnull ||
+									  !DatumGetBool(carg->constvalue));
+							break;
+						case IS_FALSE:
+							result = (!carg->constisnull &&
+									  !DatumGetBool(carg->constvalue));
+							break;
+						case IS_NOT_FALSE:
+							result = (carg->constisnull ||
+									  DatumGetBool(carg->constvalue));
+							break;
+						case IS_UNKNOWN:
+							result = carg->constisnull;
+							break;
+						case IS_NOT_UNKNOWN:
+							result = !carg->constisnull;
+							break;
+						default:
+							elog(ERROR, "unrecognized booltesttype: %d",
+								 (int) btest->booltesttype);
+							result = false; /* keep compiler quiet */
+							break;
+					}
+
+					return makeBoolConst(result, false);
+				}
+
+				newbtest = makeNode(BooleanTest);
+				newbtest->arg = (Expr *) arg;
+				newbtest->booltesttype = btest->booltesttype;
+				newbtest->location = btest->location;
+				return (Node *) newbtest;
+			}
+		case T_CoerceToDomain:
+			{
+				/*
+				 * If the domain currently has no constraints, we replace the
+				 * CoerceToDomain node with a simple RelabelType, which is
+				 * both far faster to execute and more amenable to later
+				 * optimization.  We must then mark the plan as needing to be
+				 * rebuilt if the domain's constraints change.
+				 *
+				 * Also, in estimation mode, always replace CoerceToDomain
+				 * nodes, effectively assuming that the coercion will succeed.
+				 */
+				CoerceToDomain *cdomain = (CoerceToDomain *) node;
+				CoerceToDomain *newcdomain;
+				Node	   *arg;
+
+				arg = eval_const_expressions_mutator((Node *) cdomain->arg,
+													 context);
+				if (context->estimate ||
+					!DomainHasConstraints(cdomain->resulttype))
+				{
+					/* Record dependency, if this isn't estimation mode */
+					if (context->root && !context->estimate)
+						record_plan_type_dependency(context->root,
+													cdomain->resulttype);
+
+					/* Generate RelabelType to substitute for CoerceToDomain */
+					return applyRelabelType(arg,
+											cdomain->resulttype,
+											cdomain->resulttypmod,
+											cdomain->resultcollid,
+											cdomain->coercionformat,
+											cdomain->location,
+											true);
+				}
+
+				newcdomain = makeNode(CoerceToDomain);
+				newcdomain->arg = (Expr *) arg;
+				newcdomain->resulttype = cdomain->resulttype;
+				newcdomain->resulttypmod = cdomain->resulttypmod;
+				newcdomain->resultcollid = cdomain->resultcollid;
+				newcdomain->coercionformat = cdomain->coercionformat;
+				newcdomain->location = cdomain->location;
+				return (Node *) newcdomain;
+			}
+		case T_PlaceHolderVar:
+
+			/*
+			 * In estimation mode, just strip the PlaceHolderVar node
+			 * altogether; this amounts to estimating that the contained value
+			 * won't be forced to null by an outer join.  In regular mode we
+			 * just use the default behavior (ie, simplify the expression but
+			 * leave the PlaceHolderVar node intact).
+			 */
+			if (context->estimate)
+			{
+				PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+				return eval_const_expressions_mutator((Node *) phv->phexpr,
+													  context);
+			}
+			break;
+		case T_ConvertRowtypeExpr:
+			{
+				ConvertRowtypeExpr *cre = castNode(ConvertRowtypeExpr, node);
+				Node	   *arg;
+				ConvertRowtypeExpr *newcre;
+
+				arg = eval_const_expressions_mutator((Node *) cre->arg,
+													 context);
+
+				newcre = makeNode(ConvertRowtypeExpr);
+				newcre->resulttype = cre->resulttype;
+				newcre->convertformat = cre->convertformat;
+				newcre->location = cre->location;
+
+				/*
+				 * In case of a nested ConvertRowtypeExpr, we can convert the
+				 * leaf row directly to the topmost row format without any
+				 * intermediate conversions. (This works because
+				 * ConvertRowtypeExpr is used only for child->parent
+				 * conversion in inheritance trees, which works by exact match
+				 * of column name, and a column absent in an intermediate
+				 * result can't be present in the final result.)
+				 *
+				 * No need to check more than one level deep, because the
+				 * above recursion will have flattened anything else.
+				 */
+				if (arg != NULL && IsA(arg, ConvertRowtypeExpr))
+				{
+					ConvertRowtypeExpr *argcre = (ConvertRowtypeExpr *) arg;
+
+					arg = (Node *) argcre->arg;
+
+					/*
+					 * Make sure an outer implicit conversion can't hide an
+					 * inner explicit one.
+					 */
+					if (newcre->convertformat == COERCE_IMPLICIT_CAST)
+						newcre->convertformat = argcre->convertformat;
+				}
+
+				newcre->arg = (Expr *) arg;
+
+				if (arg != NULL && IsA(arg, Const))
+					return ece_evaluate_expr((Node *) newcre);
+				return (Node *) newcre;
+			}
+		default:
+			break;
+	}
+
+	/*
+	 * For any node type not handled above, copy the node unchanged but
+	 * const-simplify its subexpressions.  This is the correct thing for node
+	 * types whose behavior might change between planning and execution, such
+	 * as CurrentOfExpr.  It's also a safe default for new node types not
+	 * known to this routine.
+	 */
+	return ece_generic_processing(node);
+}
+
+/*
+ * Subroutine for eval_const_expressions: check for non-Const nodes.
+ *
+ * We can abort recursion immediately on finding a non-Const node.  This is
+ * critical for performance, else eval_const_expressions_mutator would take
+ * O(N^2) time on non-simplifiable trees.  However, we do need to descend
+ * into List nodes since expression_tree_walker sometimes invokes the walker
+ * function directly on List subtrees.
+ */
+static bool
+contain_non_const_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Const))
+		return false;
+	if (IsA(node, List))
+		return expression_tree_walker(node, contain_non_const_walker, context);
+	/* Otherwise, abort the tree traversal and return true */
+	return true;
+}
+
+/*
+ * Subroutine for eval_const_expressions: check if a function is OK to evaluate
+ */
+static bool
+ece_function_is_safe(Oid funcid, eval_const_expressions_context *context)
+{
+	char		provolatile = func_volatile(funcid);
+
+	/*
+	 * Ordinarily we are only allowed to simplify immutable functions. But for
+	 * purposes of estimation, we consider it okay to simplify functions that
+	 * are merely stable; the risk that the result might change from planning
+	 * time to execution time is worth taking in preference to not being able
+	 * to estimate the value at all.
+	 */
+	if (provolatile == PROVOLATILE_IMMUTABLE)
+		return true;
+	if (context->estimate && provolatile == PROVOLATILE_STABLE)
+		return true;
+	return false;
+}
+
+/*
+ * Subroutine for eval_const_expressions: process arguments of an OR clause
+ *
+ * This includes flattening of nested ORs as well as recursion to
+ * eval_const_expressions to simplify the OR arguments.
+ *
+ * After simplification, OR arguments are handled as follows:
+ *		non constant: keep
+ *		FALSE: drop (does not affect result)
+ *		TRUE: force result to TRUE
+ *		NULL: keep only one
+ * We must keep one NULL input because OR expressions evaluate to NULL when no
+ * input is TRUE and at least one is NULL.  We don't actually include the NULL
+ * here, that's supposed to be done by the caller.
+ *
+ * The output arguments *haveNull and *forceTrue must be initialized false
+ * by the caller.  They will be set true if a NULL constant or TRUE constant,
+ * respectively, is detected anywhere in the argument list.
+ */
+static List *
+simplify_or_arguments(List *args,
+					  eval_const_expressions_context *context,
+					  bool *haveNull, bool *forceTrue)
+{
+	List	   *newargs = NIL;
+	List	   *unprocessed_args;
+
+	/*
+	 * We want to ensure that any OR immediately beneath another OR gets
+	 * flattened into a single OR-list, so as to simplify later reasoning.
+	 *
+	 * To avoid stack overflow from recursion of eval_const_expressions, we
+	 * resort to some tenseness here: we keep a list of not-yet-processed
+	 * inputs, and handle flattening of nested ORs by prepending to the to-do
+	 * list instead of recursing.  Now that the parser generates N-argument
+	 * ORs from simple lists, this complexity is probably less necessary than
+	 * it once was, but we might as well keep the logic.
+	 */
+	unprocessed_args = list_copy(args);
+	while (unprocessed_args)
+	{
+		Node	   *arg = (Node *) linitial(unprocessed_args);
+
+		unprocessed_args = list_delete_first(unprocessed_args);
+
+		/* flatten nested ORs as per above comment */
+		if (is_orclause(arg))
+		{
+			List	   *subargs = ((BoolExpr *) arg)->args;
+			List	   *oldlist = unprocessed_args;
+
+			unprocessed_args = list_concat_copy(subargs, unprocessed_args);
+			/* perhaps-overly-tense code to avoid leaking old lists */
+			list_free(oldlist);
+			continue;
+		}
+
+		/* If it's not an OR, simplify it */
+		arg = eval_const_expressions_mutator(arg, context);
+
+		/*
+		 * It is unlikely but not impossible for simplification of a non-OR
+		 * clause to produce an OR.  Recheck, but don't be too tense about it
+		 * since it's not a mainstream case.  In particular we don't worry
+		 * about const-simplifying the input twice, nor about list leakage.
+		 */
+		if (is_orclause(arg))
+		{
+			List	   *subargs = ((BoolExpr *) arg)->args;
+
+			unprocessed_args = list_concat_copy(subargs, unprocessed_args);
+			continue;
+		}
+
+		/*
+		 * OK, we have a const-simplified non-OR argument.  Process it per
+		 * comments above.
+		 */
+		if (IsA(arg, Const))
+		{
+			Const	   *const_input = (Const *) arg;
+
+			if (const_input->constisnull)
+				*haveNull = true;
+			else if (DatumGetBool(const_input->constvalue))
+			{
+				*forceTrue = true;
+
+				/*
+				 * Once we detect a TRUE result we can just exit the loop
+				 * immediately.  However, if we ever add a notion of
+				 * non-removable functions, we'd need to keep scanning.
+				 */
+				return NIL;
+			}
+			/* otherwise, we can drop the constant-false input */
+			continue;
+		}
+
+		/* else emit the simplified arg into the result list */
+		newargs = lappend(newargs, arg);
+	}
+
+	return newargs;
+}
+
+/*
+ * Subroutine for eval_const_expressions: process arguments of an AND clause
+ *
+ * This includes flattening of nested ANDs as well as recursion to
+ * eval_const_expressions to simplify the AND arguments.
+ *
+ * After simplification, AND arguments are handled as follows:
+ *		non constant: keep
+ *		TRUE: drop (does not affect result)
+ *		FALSE: force result to FALSE
+ *		NULL: keep only one
+ * We must keep one NULL input because AND expressions evaluate to NULL when
+ * no input is FALSE and at least one is NULL.  We don't actually include the
+ * NULL here, that's supposed to be done by the caller.
+ *
+ * The output arguments *haveNull and *forceFalse must be initialized false
+ * by the caller.  They will be set true if a null constant or false constant,
+ * respectively, is detected anywhere in the argument list.
+ */
+static List *
+simplify_and_arguments(List *args,
+					   eval_const_expressions_context *context,
+					   bool *haveNull, bool *forceFalse)
+{
+	List	   *newargs = NIL;
+	List	   *unprocessed_args;
+
+	/* See comments in simplify_or_arguments */
+	unprocessed_args = list_copy(args);
+	while (unprocessed_args)
+	{
+		Node	   *arg = (Node *) linitial(unprocessed_args);
+
+		unprocessed_args = list_delete_first(unprocessed_args);
+
+		/* flatten nested ANDs as per above comment */
+		if (is_andclause(arg))
+		{
+			List	   *subargs = ((BoolExpr *) arg)->args;
+			List	   *oldlist = unprocessed_args;
+
+			unprocessed_args = list_concat_copy(subargs, unprocessed_args);
+			/* perhaps-overly-tense code to avoid leaking old lists */
+			list_free(oldlist);
+			continue;
+		}
+
+		/* If it's not an AND, simplify it */
+		arg = eval_const_expressions_mutator(arg, context);
+
+		/*
+		 * It is unlikely but not impossible for simplification of a non-AND
+		 * clause to produce an AND.  Recheck, but don't be too tense about it
+		 * since it's not a mainstream case.  In particular we don't worry
+		 * about const-simplifying the input twice, nor about list leakage.
+		 */
+		if (is_andclause(arg))
+		{
+			List	   *subargs = ((BoolExpr *) arg)->args;
+
+			unprocessed_args = list_concat_copy(subargs, unprocessed_args);
+			continue;
+		}
+
+		/*
+		 * OK, we have a const-simplified non-AND argument.  Process it per
+		 * comments above.
+		 */
+		if (IsA(arg, Const))
+		{
+			Const	   *const_input = (Const *) arg;
+
+			if (const_input->constisnull)
+				*haveNull = true;
+			else if (!DatumGetBool(const_input->constvalue))
+			{
+				*forceFalse = true;
+
+				/*
+				 * Once we detect a FALSE result we can just exit the loop
+				 * immediately.  However, if we ever add a notion of
+				 * non-removable functions, we'd need to keep scanning.
+				 */
+				return NIL;
+			}
+			/* otherwise, we can drop the constant-true input */
+			continue;
+		}
+
+		/* else emit the simplified arg into the result list */
+		newargs = lappend(newargs, arg);
+	}
+
+	return newargs;
+}
+
+/*
+ * Subroutine for eval_const_expressions: try to simplify boolean equality
+ * or inequality condition
+ *
+ * Inputs are the operator OID and the simplified arguments to the operator.
+ * Returns a simplified expression if successful, or NULL if cannot
+ * simplify the expression.
+ *
+ * The idea here is to reduce "x = true" to "x" and "x = false" to "NOT x",
+ * or similarly "x <> true" to "NOT x" and "x <> false" to "x".
+ * This is only marginally useful in itself, but doing it in constant folding
+ * ensures that we will recognize these forms as being equivalent in, for
+ * example, partial index matching.
+ *
+ * We come here only if simplify_function has failed; therefore we cannot
+ * see two constant inputs, nor a constant-NULL input.
+ */
+static Node *
+simplify_boolean_equality(Oid opno, List *args)
+{
+	Node	   *leftop;
+	Node	   *rightop;
+
+	Assert(list_length(args) == 2);
+	leftop = linitial(args);
+	rightop = lsecond(args);
+	if (leftop && IsA(leftop, Const))
+	{
+		Assert(!((Const *) leftop)->constisnull);
+		if (opno == BooleanEqualOperator)
+		{
+			if (DatumGetBool(((Const *) leftop)->constvalue))
+				return rightop; /* true = foo */
+			else
+				return negate_clause(rightop);	/* false = foo */
+		}
+		else
+		{
+			if (DatumGetBool(((Const *) leftop)->constvalue))
+				return negate_clause(rightop);	/* true <> foo */
+			else
+				return rightop; /* false <> foo */
+		}
+	}
+	if (rightop && IsA(rightop, Const))
+	{
+		Assert(!((Const *) rightop)->constisnull);
+		if (opno == BooleanEqualOperator)
+		{
+			if (DatumGetBool(((Const *) rightop)->constvalue))
+				return leftop;	/* foo = true */
+			else
+				return negate_clause(leftop);	/* foo = false */
+		}
+		else
+		{
+			if (DatumGetBool(((Const *) rightop)->constvalue))
+				return negate_clause(leftop);	/* foo <> true */
+			else
+				return leftop;	/* foo <> false */
+		}
+	}
+	return NULL;
+}
+
+/*
+ * Subroutine for eval_const_expressions: try to simplify a function call
+ * (which might originally have been an operator; we don't care)
+ *
+ * Inputs are the function OID, actual result type OID (which is needed for
+ * polymorphic functions), result typmod, result collation, the input
+ * collation to use for the function, the original argument list (not
+ * const-simplified yet, unless process_args is false), and some flags;
+ * also the context data for eval_const_expressions.
+ *
+ * Returns a simplified expression if successful, or NULL if cannot
+ * simplify the function call.
+ *
+ * This function is also responsible for converting named-notation argument
+ * lists into positional notation and/or adding any needed default argument
+ * expressions; which is a bit grotty, but it avoids extra fetches of the
+ * function's pg_proc tuple.  For this reason, the args list is
+ * pass-by-reference.  Conversion and const-simplification of the args list
+ * will be done even if simplification of the function call itself is not
+ * possible.
+ */
+static Expr *
+simplify_function(Oid funcid, Oid result_type, int32 result_typmod,
+				  Oid result_collid, Oid input_collid, List **args_p,
+				  bool funcvariadic, bool process_args, bool allow_non_const,
+				  eval_const_expressions_context *context)
+{
+	List	   *args = *args_p;
+	HeapTuple	func_tuple;
+	Form_pg_proc func_form;
+	Expr	   *newexpr;
+
+	/*
+	 * We have three strategies for simplification: execute the function to
+	 * deliver a constant result, use a transform function to generate a
+	 * substitute node tree, or expand in-line the body of the function
+	 * definition (which only works for simple SQL-language functions, but
+	 * that is a common case).  Each case needs access to the function's
+	 * pg_proc tuple, so fetch it just once.
+	 *
+	 * Note: the allow_non_const flag suppresses both the second and third
+	 * strategies; so if !allow_non_const, simplify_function can only return a
+	 * Const or NULL.  Argument-list rewriting happens anyway, though.
+	 */
+	func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+	if (!HeapTupleIsValid(func_tuple))
+		elog(ERROR, "cache lookup failed for function %u", funcid);
+	func_form = (Form_pg_proc) GETSTRUCT(func_tuple);
+
+	/*
+	 * Process the function arguments, unless the caller did it already.
+	 *
+	 * Here we must deal with named or defaulted arguments, and then
+	 * recursively apply eval_const_expressions to the whole argument list.
+	 */
+	if (process_args)
+	{
+		args = expand_function_arguments(args, false, result_type, func_tuple);
+		args = (List *) expression_tree_mutator((Node *) args,
+												eval_const_expressions_mutator,
+												(void *) context);
+		/* Argument processing done, give it back to the caller */
+		*args_p = args;
+	}
+
+	/* Now attempt simplification of the function call proper. */
+
+	newexpr = evaluate_function(funcid, result_type, result_typmod,
+								result_collid, input_collid,
+								args, funcvariadic,
+								func_tuple, context);
+
+	if (!newexpr && allow_non_const && OidIsValid(func_form->prosupport))
+	{
+		/*
+		 * Build a SupportRequestSimplify node to pass to the support
+		 * function, pointing to a dummy FuncExpr node containing the
+		 * simplified arg list.  We use this approach to present a uniform
+		 * interface to the support function regardless of how the target
+		 * function is actually being invoked.
+		 */
+		SupportRequestSimplify req;
+		FuncExpr	fexpr;
+
+		fexpr.xpr.type = T_FuncExpr;
+		fexpr.funcid = funcid;
+		fexpr.funcresulttype = result_type;
+		fexpr.funcretset = func_form->proretset;
+		fexpr.funcvariadic = funcvariadic;
+		fexpr.funcformat = COERCE_EXPLICIT_CALL;
+		fexpr.funccollid = result_collid;
+		fexpr.inputcollid = input_collid;
+		fexpr.args = args;
+		fexpr.location = -1;
+
+		req.type = T_SupportRequestSimplify;
+		req.root = context->root;
+		req.fcall = &fexpr;
+
+		newexpr = (Expr *)
+			DatumGetPointer(OidFunctionCall1(func_form->prosupport,
+											 PointerGetDatum(&req)));
+
+		/* catch a possible API misunderstanding */
+		Assert(newexpr != (Expr *) &fexpr);
+	}
+
+	if (!newexpr && allow_non_const)
+		newexpr = inline_function(funcid, result_type, result_collid,
+								  input_collid, args, funcvariadic,
+								  func_tuple, context);
+
+	ReleaseSysCache(func_tuple);
+
+	return newexpr;
+}
+
+/*
+ * expand_function_arguments: convert named-notation args to positional args
+ * and/or insert default args, as needed
+ *
+ * Returns a possibly-transformed version of the args list.
+ *
+ * If include_out_arguments is true, then the args list and the result
+ * include OUT arguments.
+ *
+ * The expected result type of the call must be given, for sanity-checking
+ * purposes.  Also, we ask the caller to provide the function's actual
+ * pg_proc tuple, not just its OID.
+ *
+ * If we need to change anything, the input argument list is copied, not
+ * modified.
+ *
+ * Note: this gets applied to operator argument lists too, even though the
+ * cases it handles should never occur there.  This should be OK since it
+ * will fall through very quickly if there's nothing to do.
+ */
+List *
+expand_function_arguments(List *args, bool include_out_arguments,
+						  Oid result_type, HeapTuple func_tuple)
+{
+	Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
+	Oid		   *proargtypes = funcform->proargtypes.values;
+	int			pronargs = funcform->pronargs;
+	bool		has_named_args = false;
+	ListCell   *lc;
+
+	/*
+	 * If we are asked to match to OUT arguments, then use the proallargtypes
+	 * array (which includes those); otherwise use proargtypes (which
+	 * doesn't).  Of course, if proallargtypes is null, we always use
+	 * proargtypes.  (Fetching proallargtypes is annoyingly expensive
+	 * considering that we may have nothing to do here, but fortunately the
+	 * common case is include_out_arguments == false.)
+	 */
+	if (include_out_arguments)
+	{
+		Datum		proallargtypes;
+		bool		isNull;
+
+		proallargtypes = SysCacheGetAttr(PROCOID, func_tuple,
+										 Anum_pg_proc_proallargtypes,
+										 &isNull);
+		if (!isNull)
+		{
+			ArrayType  *arr = DatumGetArrayTypeP(proallargtypes);
+
+			pronargs = ARR_DIMS(arr)[0];
+			if (ARR_NDIM(arr) != 1 ||
+				pronargs < 0 ||
+				ARR_HASNULL(arr) ||
+				ARR_ELEMTYPE(arr) != OIDOID)
+				elog(ERROR, "proallargtypes is not a 1-D Oid array or it contains nulls");
+			Assert(pronargs >= funcform->pronargs);
+			proargtypes = (Oid *) ARR_DATA_PTR(arr);
+		}
+	}
+
+	/* Do we have any named arguments? */
+	foreach(lc, args)
+	{
+		Node	   *arg = (Node *) lfirst(lc);
+
+		if (IsA(arg, NamedArgExpr))
+		{
+			has_named_args = true;
+			break;
+		}
+	}
+
+	/* If so, we must apply reorder_function_arguments */
+	if (has_named_args)
+	{
+		args = reorder_function_arguments(args, pronargs, func_tuple);
+		/* Recheck argument types and add casts if needed */
+		recheck_cast_function_args(args, result_type,
+								   proargtypes, pronargs,
+								   func_tuple);
+	}
+	else if (list_length(args) < pronargs)
+	{
+		/* No named args, but we seem to be short some defaults */
+		args = add_function_defaults(args, pronargs, func_tuple);
+		/* Recheck argument types and add casts if needed */
+		recheck_cast_function_args(args, result_type,
+								   proargtypes, pronargs,
+								   func_tuple);
+	}
+
+	return args;
+}
+
+/*
+ * reorder_function_arguments: convert named-notation args to positional args
+ *
+ * This function also inserts default argument values as needed, since it's
+ * impossible to form a truly valid positional call without that.
+ */
+static List *
+reorder_function_arguments(List *args, int pronargs, HeapTuple func_tuple)
+{
+	Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
+	int			nargsprovided = list_length(args);
+	Node	   *argarray[FUNC_MAX_ARGS];
+	ListCell   *lc;
+	int			i;
+
+	Assert(nargsprovided <= pronargs);
+	if (pronargs < 0 || pronargs > FUNC_MAX_ARGS)
+		elog(ERROR, "too many function arguments");
+	memset(argarray, 0, pronargs * sizeof(Node *));
+
+	/* Deconstruct the argument list into an array indexed by argnumber */
+	i = 0;
+	foreach(lc, args)
+	{
+		Node	   *arg = (Node *) lfirst(lc);
+
+		if (!IsA(arg, NamedArgExpr))
+		{
+			/* positional argument, assumed to precede all named args */
+			Assert(argarray[i] == NULL);
+			argarray[i++] = arg;
+		}
+		else
+		{
+			NamedArgExpr *na = (NamedArgExpr *) arg;
+
+			Assert(na->argnumber >= 0 && na->argnumber < pronargs);
+			Assert(argarray[na->argnumber] == NULL);
+			argarray[na->argnumber] = (Node *) na->arg;
+		}
+	}
+
+	/*
+	 * Fetch default expressions, if needed, and insert into array at proper
+	 * locations (they aren't necessarily consecutive or all used)
+	 */
+	if (nargsprovided < pronargs)
+	{
+		List	   *defaults = fetch_function_defaults(func_tuple);
+
+		i = pronargs - funcform->pronargdefaults;
+		foreach(lc, defaults)
+		{
+			if (argarray[i] == NULL)
+				argarray[i] = (Node *) lfirst(lc);
+			i++;
+		}
+	}
+
+	/* Now reconstruct the args list in proper order */
+	args = NIL;
+	for (i = 0; i < pronargs; i++)
+	{
+		Assert(argarray[i] != NULL);
+		args = lappend(args, argarray[i]);
+	}
+
+	return args;
+}
+
+/*
+ * add_function_defaults: add missing function arguments from its defaults
+ *
+ * This is used only when the argument list was positional to begin with,
+ * and so we know we just need to add defaults at the end.
+ */
+static List *
+add_function_defaults(List *args, int pronargs, HeapTuple func_tuple)
+{
+	int			nargsprovided = list_length(args);
+	List	   *defaults;
+	int			ndelete;
+
+	/* Get all the default expressions from the pg_proc tuple */
+	defaults = fetch_function_defaults(func_tuple);
+
+	/* Delete any unused defaults from the list */
+	ndelete = nargsprovided + list_length(defaults) - pronargs;
+	if (ndelete < 0)
+		elog(ERROR, "not enough default arguments");
+	if (ndelete > 0)
+		defaults = list_delete_first_n(defaults, ndelete);
+
+	/* And form the combined argument list, not modifying the input list */
+	return list_concat_copy(args, defaults);
+}
+
+/*
+ * fetch_function_defaults: get function's default arguments as expression list
+ */
+static List *
+fetch_function_defaults(HeapTuple func_tuple)
+{
+	List	   *defaults;
+	Datum		proargdefaults;
+	bool		isnull;
+	char	   *str;
+
+	/* The error cases here shouldn't happen, but check anyway */
+	proargdefaults = SysCacheGetAttr(PROCOID, func_tuple,
+									 Anum_pg_proc_proargdefaults,
+									 &isnull);
+	if (isnull)
+		elog(ERROR, "not enough default arguments");
+	str = TextDatumGetCString(proargdefaults);
+	defaults = castNode(List, stringToNode(str));
+	pfree(str);
+	return defaults;
+}
+
+/*
+ * recheck_cast_function_args: recheck function args and typecast as needed
+ * after adding defaults.
+ *
+ * It is possible for some of the defaulted arguments to be polymorphic;
+ * therefore we can't assume that the default expressions have the correct
+ * data types already.  We have to re-resolve polymorphics and do coercion
+ * just like the parser did.
+ *
+ * This should be a no-op if there are no polymorphic arguments,
+ * but we do it anyway to be sure.
+ *
+ * Note: if any casts are needed, the args list is modified in-place;
+ * caller should have already copied the list structure.
+ */
+static void
+recheck_cast_function_args(List *args, Oid result_type,
+						   Oid *proargtypes, int pronargs,
+						   HeapTuple func_tuple)
+{
+	Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
+	int			nargs;
+	Oid			actual_arg_types[FUNC_MAX_ARGS];
+	Oid			declared_arg_types[FUNC_MAX_ARGS];
+	Oid			rettype;
+	ListCell   *lc;
+
+	if (list_length(args) > FUNC_MAX_ARGS)
+		elog(ERROR, "too many function arguments");
+	nargs = 0;
+	foreach(lc, args)
+	{
+		actual_arg_types[nargs++] = exprType((Node *) lfirst(lc));
+	}
+	Assert(nargs == pronargs);
+	memcpy(declared_arg_types, proargtypes, pronargs * sizeof(Oid));
+	rettype = enforce_generic_type_consistency(actual_arg_types,
+											   declared_arg_types,
+											   nargs,
+											   funcform->prorettype,
+											   false);
+	/* let's just check we got the same answer as the parser did ... */
+	if (rettype != result_type)
+		elog(ERROR, "function's resolved result type changed during planning");
+
+	/* perform any necessary typecasting of arguments */
+	make_fn_arguments(NULL, args, actual_arg_types, declared_arg_types);
+}
+
+/*
+ * evaluate_function: try to pre-evaluate a function call
+ *
+ * We can do this if the function is strict and has any constant-null inputs
+ * (just return a null constant), or if the function is immutable and has all
+ * constant inputs (call it and return the result as a Const node).  In
+ * estimation mode we are willing to pre-evaluate stable functions too.
+ *
+ * Returns a simplified expression if successful, or NULL if cannot
+ * simplify the function.
+ */
+static Expr *
+evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
+				  Oid result_collid, Oid input_collid, List *args,
+				  bool funcvariadic,
+				  HeapTuple func_tuple,
+				  eval_const_expressions_context *context)
+{
+	Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
+	bool		has_nonconst_input = false;
+	bool		has_null_input = false;
+	ListCell   *arg;
+	FuncExpr   *newexpr;
+
+	/*
+	 * Can't simplify if it returns a set.
+	 */
+	if (funcform->proretset)
+		return NULL;
+
+	/*
+	 * Can't simplify if it returns RECORD.  The immediate problem is that it
+	 * will be needing an expected tupdesc which we can't supply here.
+	 *
+	 * In the case where it has OUT parameters, it could get by without an
+	 * expected tupdesc, but we still have issues: get_expr_result_type()
+	 * doesn't know how to extract type info from a RECORD constant, and in
+	 * the case of a NULL function result there doesn't seem to be any clean
+	 * way to fix that.  In view of the likelihood of there being still other
+	 * gotchas, seems best to leave the function call unreduced.
+	 */
+	if (funcform->prorettype == RECORDOID)
+		return NULL;
+
+	/*
+	 * Check for constant inputs and especially constant-NULL inputs.
+	 */
+	foreach(arg, args)
+	{
+		if (IsA(lfirst(arg), Const))
+			has_null_input |= ((Const *) lfirst(arg))->constisnull;
+		else
+			has_nonconst_input = true;
+	}
+
+	/*
+	 * If the function is strict and has a constant-NULL input, it will never
+	 * be called at all, so we can replace the call by a NULL constant, even
+	 * if there are other inputs that aren't constant, and even if the
+	 * function is not otherwise immutable.
+	 */
+	if (funcform->proisstrict && has_null_input)
+		return (Expr *) makeNullConst(result_type, result_typmod,
+									  result_collid);
+
+	/*
+	 * Otherwise, can simplify only if all inputs are constants. (For a
+	 * non-strict function, constant NULL inputs are treated the same as
+	 * constant non-NULL inputs.)
+	 */
+	if (has_nonconst_input)
+		return NULL;
+
+	/*
+	 * Ordinarily we are only allowed to simplify immutable functions. But for
+	 * purposes of estimation, we consider it okay to simplify functions that
+	 * are merely stable; the risk that the result might change from planning
+	 * time to execution time is worth taking in preference to not being able
+	 * to estimate the value at all.
+	 */
+	if (funcform->provolatile == PROVOLATILE_IMMUTABLE)
+		 /* okay */ ;
+	else if (context->estimate && funcform->provolatile == PROVOLATILE_STABLE)
+		 /* okay */ ;
+	else
+		return NULL;
+
+	/*
+	 * OK, looks like we can simplify this operator/function.
+	 *
+	 * Build a new FuncExpr node containing the already-simplified arguments.
+	 */
+	newexpr = makeNode(FuncExpr);
+	newexpr->funcid = funcid;
+	newexpr->funcresulttype = result_type;
+	newexpr->funcretset = false;
+	newexpr->funcvariadic = funcvariadic;
+	newexpr->funcformat = COERCE_EXPLICIT_CALL; /* doesn't matter */
+	newexpr->funccollid = result_collid;	/* doesn't matter */
+	newexpr->inputcollid = input_collid;
+	newexpr->args = args;
+	newexpr->location = -1;
+
+	return evaluate_expr((Expr *) newexpr, result_type, result_typmod,
+						 result_collid);
+}
+
+/*
+ * inline_function: try to expand a function call inline
+ *
+ * If the function is a sufficiently simple SQL-language function
+ * (just "SELECT expression"), then we can inline it and avoid the rather
+ * high per-call overhead of SQL functions.  Furthermore, this can expose
+ * opportunities for constant-folding within the function expression.
+ *
+ * We have to beware of some special cases however.  A directly or
+ * indirectly recursive function would cause us to recurse forever,
+ * so we keep track of which functions we are already expanding and
+ * do not re-expand them.  Also, if a parameter is used more than once
+ * in the SQL-function body, we require it not to contain any volatile
+ * functions (volatiles might deliver inconsistent answers) nor to be
+ * unreasonably expensive to evaluate.  The expensiveness check not only
+ * prevents us from doing multiple evaluations of an expensive parameter
+ * at runtime, but is a safety value to limit growth of an expression due
+ * to repeated inlining.
+ *
+ * We must also beware of changing the volatility or strictness status of
+ * functions by inlining them.
+ *
+ * Also, at the moment we can't inline functions returning RECORD.  This
+ * doesn't work in the general case because it discards information such
+ * as OUT-parameter declarations.
+ *
+ * Also, context-dependent expression nodes in the argument list are trouble.
+ *
+ * Returns a simplified expression if successful, or NULL if cannot
+ * simplify the function.
+ */
+static Expr *
+inline_function(Oid funcid, Oid result_type, Oid result_collid,
+				Oid input_collid, List *args,
+				bool funcvariadic,
+				HeapTuple func_tuple,
+				eval_const_expressions_context *context)
+{
+	Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
+	char	   *src;
+	Datum		tmp;
+	bool		isNull;
+	MemoryContext oldcxt;
+	MemoryContext mycxt;
+	inline_error_callback_arg callback_arg;
+	ErrorContextCallback sqlerrcontext;
+	FuncExpr   *fexpr;
+	SQLFunctionParseInfoPtr pinfo;
+	TupleDesc	rettupdesc;
+	ParseState *pstate;
+	List	   *raw_parsetree_list;
+	List	   *querytree_list;
+	Query	   *querytree;
+	Node	   *newexpr;
+	int		   *usecounts;
+	ListCell   *arg;
+	int			i;
+
+	/*
+	 * Forget it if the function is not SQL-language or has other showstopper
+	 * properties.  (The prokind and nargs checks are just paranoia.)
+	 */
+	if (funcform->prolang != SQLlanguageId ||
+		funcform->prokind != PROKIND_FUNCTION ||
+		funcform->prosecdef ||
+		funcform->proretset ||
+		funcform->prorettype == RECORDOID ||
+		!heap_attisnull(func_tuple, Anum_pg_proc_proconfig, NULL) ||
+		funcform->pronargs != list_length(args))
+		return NULL;
+
+	/* Check for recursive function, and give up trying to expand if so */
+	if (list_member_oid(context->active_fns, funcid))
+		return NULL;
+
+	/* Check permission to call function (fail later, if not) */
+	if (pg_proc_aclcheck(funcid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
+		return NULL;
+
+	/* Check whether a plugin wants to hook function entry/exit */
+	if (FmgrHookIsNeeded(funcid))
+		return NULL;
+
+	/*
+	 * Make a temporary memory context, so that we don't leak all the stuff
+	 * that parsing might create.
+	 */
+	mycxt = AllocSetContextCreate(CurrentMemoryContext,
+								  "inline_function",
+								  ALLOCSET_DEFAULT_SIZES);
+	oldcxt = MemoryContextSwitchTo(mycxt);
+
+	/*
+	 * We need a dummy FuncExpr node containing the already-simplified
+	 * arguments.  (In some cases we don't really need it, but building it is
+	 * cheap enough that it's not worth contortions to avoid.)
+	 */
+	fexpr = makeNode(FuncExpr);
+	fexpr->funcid = funcid;
+	fexpr->funcresulttype = result_type;
+	fexpr->funcretset = false;
+	fexpr->funcvariadic = funcvariadic;
+	fexpr->funcformat = COERCE_EXPLICIT_CALL;	/* doesn't matter */
+	fexpr->funccollid = result_collid;	/* doesn't matter */
+	fexpr->inputcollid = input_collid;
+	fexpr->args = args;
+	fexpr->location = -1;
+
+	/* Fetch the function body */
+	tmp = SysCacheGetAttr(PROCOID,
+						  func_tuple,
+						  Anum_pg_proc_prosrc,
+						  &isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", funcid);
+	src = TextDatumGetCString(tmp);
+
+	/*
+	 * Setup error traceback support for ereport().  This is so that we can
+	 * finger the function that bad information came from.
+	 */
+	callback_arg.proname = NameStr(funcform->proname);
+	callback_arg.prosrc = src;
+
+	sqlerrcontext.callback = sql_inline_error_callback;
+	sqlerrcontext.arg = (void *) &callback_arg;
+	sqlerrcontext.previous = error_context_stack;
+	error_context_stack = &sqlerrcontext;
+
+	/* If we have prosqlbody, pay attention to that not prosrc */
+	tmp = SysCacheGetAttr(PROCOID,
+						  func_tuple,
+						  Anum_pg_proc_prosqlbody,
+						  &isNull);
+	if (!isNull)
+	{
+		Node	   *n;
+		List	   *querytree_list;
+
+		n = stringToNode(TextDatumGetCString(tmp));
+		if (IsA(n, List))
+			querytree_list = linitial_node(List, castNode(List, n));
+		else
+			querytree_list = list_make1(n);
+		if (list_length(querytree_list) != 1)
+			goto fail;
+		querytree = linitial(querytree_list);
+
+		/*
+		 * Because we'll insist below that the querytree have an empty rtable
+		 * and no sublinks, it cannot have any relation references that need
+		 * to be locked or rewritten.  So we can omit those steps.
+		 */
+	}
+	else
+	{
+		/* Set up to handle parameters while parsing the function body. */
+		pinfo = prepare_sql_fn_parse_info(func_tuple,
+										  (Node *) fexpr,
+										  input_collid);
+
+		/*
+		 * We just do parsing and parse analysis, not rewriting, because
+		 * rewriting will not affect table-free-SELECT-only queries, which is
+		 * all that we care about.  Also, we can punt as soon as we detect
+		 * more than one command in the function body.
+		 */
+		raw_parsetree_list = pg_parse_query(src);
+		if (list_length(raw_parsetree_list) != 1)
+			goto fail;
+
+		pstate = make_parsestate(NULL);
+		pstate->p_sourcetext = src;
+		sql_fn_parser_setup(pstate, pinfo);
+
+		querytree = transformTopLevelStmt(pstate, linitial(raw_parsetree_list));
+
+		free_parsestate(pstate);
+	}
+
+	/*
+	 * The single command must be a simple "SELECT expression".
+	 *
+	 * Note: if you change the tests involved in this, see also plpgsql's
+	 * exec_simple_check_plan().  That generally needs to have the same idea
+	 * of what's a "simple expression", so that inlining a function that
+	 * previously wasn't inlined won't change plpgsql's conclusion.
+	 */
+	if (!IsA(querytree, Query) ||
+		querytree->commandType != CMD_SELECT ||
+		querytree->hasAggs ||
+		querytree->hasWindowFuncs ||
+		querytree->hasTargetSRFs ||
+		querytree->hasSubLinks ||
+		querytree->cteList ||
+		querytree->rtable ||
+		querytree->jointree->fromlist ||
+		querytree->jointree->quals ||
+		querytree->groupClause ||
+		querytree->groupingSets ||
+		querytree->havingQual ||
+		querytree->windowClause ||
+		querytree->distinctClause ||
+		querytree->sortClause ||
+		querytree->limitOffset ||
+		querytree->limitCount ||
+		querytree->setOperations ||
+		list_length(querytree->targetList) != 1)
+		goto fail;
+
+	/* If the function result is composite, resolve it */
+	(void) get_expr_result_type((Node *) fexpr,
+								NULL,
+								&rettupdesc);
+
+	/*
+	 * Make sure the function (still) returns what it's declared to.  This
+	 * will raise an error if wrong, but that's okay since the function would
+	 * fail at runtime anyway.  Note that check_sql_fn_retval will also insert
+	 * a coercion if needed to make the tlist expression match the declared
+	 * type of the function.
+	 *
+	 * Note: we do not try this until we have verified that no rewriting was
+	 * needed; that's probably not important, but let's be careful.
+	 */
+	querytree_list = list_make1(querytree);
+	if (check_sql_fn_retval(list_make1(querytree_list),
+							result_type, rettupdesc,
+							false, NULL))
+		goto fail;				/* reject whole-tuple-result cases */
+
+	/*
+	 * Given the tests above, check_sql_fn_retval shouldn't have decided to
+	 * inject a projection step, but let's just make sure.
+	 */
+	if (querytree != linitial(querytree_list))
+		goto fail;
+
+	/* Now we can grab the tlist expression */
+	newexpr = (Node *) ((TargetEntry *) linitial(querytree->targetList))->expr;
+
+	/*
+	 * If the SQL function returns VOID, we can only inline it if it is a
+	 * SELECT of an expression returning VOID (ie, it's just a redirection to
+	 * another VOID-returning function).  In all non-VOID-returning cases,
+	 * check_sql_fn_retval should ensure that newexpr returns the function's
+	 * declared result type, so this test shouldn't fail otherwise; but we may
+	 * as well cope gracefully if it does.
+	 */
+	if (exprType(newexpr) != result_type)
+		goto fail;
+
+	/*
+	 * Additional validity checks on the expression.  It mustn't be more
+	 * volatile than the surrounding function (this is to avoid breaking hacks
+	 * that involve pretending a function is immutable when it really ain't).
+	 * If the surrounding function is declared strict, then the expression
+	 * must contain only strict constructs and must use all of the function
+	 * parameters (this is overkill, but an exact analysis is hard).
+	 */
+	if (funcform->provolatile == PROVOLATILE_IMMUTABLE &&
+		contain_mutable_functions(newexpr))
+		goto fail;
+	else if (funcform->provolatile == PROVOLATILE_STABLE &&
+			 contain_volatile_functions(newexpr))
+		goto fail;
+
+	if (funcform->proisstrict &&
+		contain_nonstrict_functions(newexpr))
+		goto fail;
+
+	/*
+	 * If any parameter expression contains a context-dependent node, we can't
+	 * inline, for fear of putting such a node into the wrong context.
+	 */
+	if (contain_context_dependent_node((Node *) args))
+		goto fail;
+
+	/*
+	 * We may be able to do it; there are still checks on parameter usage to
+	 * make, but those are most easily done in combination with the actual
+	 * substitution of the inputs.  So start building expression with inputs
+	 * substituted.
+	 */
+	usecounts = (int *) palloc0(funcform->pronargs * sizeof(int));
+	newexpr = substitute_actual_parameters(newexpr, funcform->pronargs,
+										   args, usecounts);
+
+	/* Now check for parameter usage */
+	i = 0;
+	foreach(arg, args)
+	{
+		Node	   *param = lfirst(arg);
+
+		if (usecounts[i] == 0)
+		{
+			/* Param not used at all: uncool if func is strict */
+			if (funcform->proisstrict)
+				goto fail;
+		}
+		else if (usecounts[i] != 1)
+		{
+			/* Param used multiple times: uncool if expensive or volatile */
+			QualCost	eval_cost;
+
+			/*
+			 * We define "expensive" as "contains any subplan or more than 10
+			 * operators".  Note that the subplan search has to be done
+			 * explicitly, since cost_qual_eval() will barf on unplanned
+			 * subselects.
+			 */
+			if (contain_subplans(param))
+				goto fail;
+			cost_qual_eval(&eval_cost, list_make1(param), NULL);
+			if (eval_cost.startup + eval_cost.per_tuple >
+				10 * cpu_operator_cost)
+				goto fail;
+
+			/*
+			 * Check volatility last since this is more expensive than the
+			 * above tests
+			 */
+			if (contain_volatile_functions(param))
+				goto fail;
+		}
+		i++;
+	}
+
+	/*
+	 * Whew --- we can make the substitution.  Copy the modified expression
+	 * out of the temporary memory context, and clean up.
+	 */
+	MemoryContextSwitchTo(oldcxt);
+
+	newexpr = copyObject(newexpr);
+
+	MemoryContextDelete(mycxt);
+
+	/*
+	 * If the result is of a collatable type, force the result to expose the
+	 * correct collation.  In most cases this does not matter, but it's
+	 * possible that the function result is used directly as a sort key or in
+	 * other places where we expect exprCollation() to tell the truth.
+	 */
+	if (OidIsValid(result_collid))
+	{
+		Oid			exprcoll = exprCollation(newexpr);
+
+		if (OidIsValid(exprcoll) && exprcoll != result_collid)
+		{
+			CollateExpr *newnode = makeNode(CollateExpr);
+
+			newnode->arg = (Expr *) newexpr;
+			newnode->collOid = result_collid;
+			newnode->location = -1;
+
+			newexpr = (Node *) newnode;
+		}
+	}
+
+	/*
+	 * Since there is now no trace of the function in the plan tree, we must
+	 * explicitly record the plan's dependency on the function.
+	 */
+	if (context->root)
+		record_plan_function_dependency(context->root, funcid);
+
+	/*
+	 * Recursively try to simplify the modified expression.  Here we must add
+	 * the current function to the context list of active functions.
+	 */
+	context->active_fns = lappend_oid(context->active_fns, funcid);
+	newexpr = eval_const_expressions_mutator(newexpr, context);
+	context->active_fns = list_delete_last(context->active_fns);
+
+	error_context_stack = sqlerrcontext.previous;
+
+	return (Expr *) newexpr;
+
+	/* Here if func is not inlinable: release temp memory and return NULL */
+fail:
+	MemoryContextSwitchTo(oldcxt);
+	MemoryContextDelete(mycxt);
+	error_context_stack = sqlerrcontext.previous;
+
+	return NULL;
+}
+
+/*
+ * Replace Param nodes by appropriate actual parameters
+ */
+static Node *
+substitute_actual_parameters(Node *expr, int nargs, List *args,
+							 int *usecounts)
+{
+	substitute_actual_parameters_context context;
+
+	context.nargs = nargs;
+	context.args = args;
+	context.usecounts = usecounts;
+
+	return substitute_actual_parameters_mutator(expr, &context);
+}
+
+static Node *
+substitute_actual_parameters_mutator(Node *node,
+									 substitute_actual_parameters_context *context)
+{
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Param))
+	{
+		Param	   *param = (Param *) node;
+
+		if (param->paramkind != PARAM_EXTERN)
+			elog(ERROR, "unexpected paramkind: %d", (int) param->paramkind);
+		if (param->paramid <= 0 || param->paramid > context->nargs)
+			elog(ERROR, "invalid paramid: %d", param->paramid);
+
+		/* Count usage of parameter */
+		context->usecounts[param->paramid - 1]++;
+
+		/* Select the appropriate actual arg and replace the Param with it */
+		/* We don't need to copy at this time (it'll get done later) */
+		return list_nth(context->args, param->paramid - 1);
+	}
+	return expression_tree_mutator(node, substitute_actual_parameters_mutator,
+								   (void *) context);
+}
+
+/*
+ * error context callback to let us supply a call-stack traceback
+ */
+static void
+sql_inline_error_callback(void *arg)
+{
+	inline_error_callback_arg *callback_arg = (inline_error_callback_arg *) arg;
+	int			syntaxerrposition;
+
+	/* If it's a syntax error, convert to internal syntax error report */
+	syntaxerrposition = geterrposition();
+	if (syntaxerrposition > 0)
+	{
+		errposition(0);
+		internalerrposition(syntaxerrposition);
+		internalerrquery(callback_arg->prosrc);
+	}
+
+	errcontext("SQL function \"%s\" during inlining", callback_arg->proname);
+}
+
+/*
+ * evaluate_expr: pre-evaluate a constant expression
+ *
+ * We use the executor's routine ExecEvalExpr() to avoid duplication of
+ * code and ensure we get the same result as the executor would get.
+ */
+Expr *
+evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod,
+			  Oid result_collation)
+{
+	EState	   *estate;
+	ExprState  *exprstate;
+	MemoryContext oldcontext;
+	Datum		const_val;
+	bool		const_is_null;
+	int16		resultTypLen;
+	bool		resultTypByVal;
+
+	/*
+	 * To use the executor, we need an EState.
+	 */
+	estate = CreateExecutorState();
+
+	/* We can use the estate's working context to avoid memory leaks. */
+	oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
+
+	/* Make sure any opfuncids are filled in. */
+	fix_opfuncids((Node *) expr);
+
+	/*
+	 * Prepare expr for execution.  (Note: we can't use ExecPrepareExpr
+	 * because it'd result in recursively invoking eval_const_expressions.)
+	 */
+	exprstate = ExecInitExpr(expr, NULL);
+
+	/*
+	 * And evaluate it.
+	 *
+	 * It is OK to use a default econtext because none of the ExecEvalExpr()
+	 * code used in this situation will use econtext.  That might seem
+	 * fortuitous, but it's not so unreasonable --- a constant expression does
+	 * not depend on context, by definition, n'est ce pas?
+	 */
+	const_val = ExecEvalExprSwitchContext(exprstate,
+										  GetPerTupleExprContext(estate),
+										  &const_is_null);
+
+	/* Get info needed about result datatype */
+	get_typlenbyval(result_type, &resultTypLen, &resultTypByVal);
+
+	/* Get back to outer memory context */
+	MemoryContextSwitchTo(oldcontext);
+
+	/*
+	 * Must copy result out of sub-context used by expression eval.
+	 *
+	 * Also, if it's varlena, forcibly detoast it.  This protects us against
+	 * storing TOAST pointers into plans that might outlive the referenced
+	 * data.  (makeConst would handle detoasting anyway, but it's worth a few
+	 * extra lines here so that we can do the copy and detoast in one step.)
+	 */
+	if (!const_is_null)
+	{
+		if (resultTypLen == -1)
+			const_val = PointerGetDatum(PG_DETOAST_DATUM_COPY(const_val));
+		else
+			const_val = datumCopy(const_val, resultTypByVal, resultTypLen);
+	}
+
+	/* Release all the junk we just created */
+	FreeExecutorState(estate);
+
+	/*
+	 * Make the constant result node.
+	 */
+	return (Expr *) makeConst(result_type, result_typmod, result_collation,
+							  resultTypLen,
+							  const_val, const_is_null,
+							  resultTypByVal);
+}
+
+
+/*
+ * inline_set_returning_function
+ *		Attempt to "inline" a set-returning function in the FROM clause.
+ *
+ * "rte" is an RTE_FUNCTION rangetable entry.  If it represents a call of a
+ * set-returning SQL function that can safely be inlined, expand the function
+ * and return the substitute Query structure.  Otherwise, return NULL.
+ *
+ * We assume that the RTE's expression has already been put through
+ * eval_const_expressions(), which among other things will take care of
+ * default arguments and named-argument notation.
+ *
+ * This has a good deal of similarity to inline_function(), but that's
+ * for the non-set-returning case, and there are enough differences to
+ * justify separate functions.
+ */
+Query *
+inline_set_returning_function(PlannerInfo *root, RangeTblEntry *rte)
+{
+	RangeTblFunction *rtfunc;
+	FuncExpr   *fexpr;
+	Oid			func_oid;
+	HeapTuple	func_tuple;
+	Form_pg_proc funcform;
+	char	   *src;
+	Datum		tmp;
+	bool		isNull;
+	MemoryContext oldcxt;
+	MemoryContext mycxt;
+	inline_error_callback_arg callback_arg;
+	ErrorContextCallback sqlerrcontext;
+	SQLFunctionParseInfoPtr pinfo;
+	TypeFuncClass functypclass;
+	TupleDesc	rettupdesc;
+	List	   *raw_parsetree_list;
+	List	   *querytree_list;
+	Query	   *querytree;
+
+	Assert(rte->rtekind == RTE_FUNCTION);
+
+	/*
+	 * It doesn't make a lot of sense for a SQL SRF to refer to itself in its
+	 * own FROM clause, since that must cause infinite recursion at runtime.
+	 * It will cause this code to recurse too, so check for stack overflow.
+	 * (There's no need to do more.)
+	 */
+	check_stack_depth();
+
+	/* Fail if the RTE has ORDINALITY - we don't implement that here. */
+	if (rte->funcordinality)
+		return NULL;
+
+	/* Fail if RTE isn't a single, simple FuncExpr */
+	if (list_length(rte->functions) != 1)
+		return NULL;
+	rtfunc = (RangeTblFunction *) linitial(rte->functions);
+
+	if (!IsA(rtfunc->funcexpr, FuncExpr))
+		return NULL;
+	fexpr = (FuncExpr *) rtfunc->funcexpr;
+
+	func_oid = fexpr->funcid;
+
+	/*
+	 * The function must be declared to return a set, else inlining would
+	 * change the results if the contained SELECT didn't return exactly one
+	 * row.
+	 */
+	if (!fexpr->funcretset)
+		return NULL;
+
+	/*
+	 * Refuse to inline if the arguments contain any volatile functions or
+	 * sub-selects.  Volatile functions are rejected because inlining may
+	 * result in the arguments being evaluated multiple times, risking a
+	 * change in behavior.  Sub-selects are rejected partly for implementation
+	 * reasons (pushing them down another level might change their behavior)
+	 * and partly because they're likely to be expensive and so multiple
+	 * evaluation would be bad.
+	 */
+	if (contain_volatile_functions((Node *) fexpr->args) ||
+		contain_subplans((Node *) fexpr->args))
+		return NULL;
+
+	/* Check permission to call function (fail later, if not) */
+	if (pg_proc_aclcheck(func_oid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
+		return NULL;
+
+	/* Check whether a plugin wants to hook function entry/exit */
+	if (FmgrHookIsNeeded(func_oid))
+		return NULL;
+
+	/*
+	 * OK, let's take a look at the function's pg_proc entry.
+	 */
+	func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(func_oid));
+	if (!HeapTupleIsValid(func_tuple))
+		elog(ERROR, "cache lookup failed for function %u", func_oid);
+	funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
+
+	/*
+	 * Forget it if the function is not SQL-language or has other showstopper
+	 * properties.  In particular it mustn't be declared STRICT, since we
+	 * couldn't enforce that.  It also mustn't be VOLATILE, because that is
+	 * supposed to cause it to be executed with its own snapshot, rather than
+	 * sharing the snapshot of the calling query.  We also disallow returning
+	 * SETOF VOID, because inlining would result in exposing the actual result
+	 * of the function's last SELECT, which should not happen in that case.
+	 * (Rechecking prokind, proretset, and pronargs is just paranoia.)
+	 */
+	if (funcform->prolang != SQLlanguageId ||
+		funcform->prokind != PROKIND_FUNCTION ||
+		funcform->proisstrict ||
+		funcform->provolatile == PROVOLATILE_VOLATILE ||
+		funcform->prorettype == VOIDOID ||
+		funcform->prosecdef ||
+		!funcform->proretset ||
+		list_length(fexpr->args) != funcform->pronargs ||
+		!heap_attisnull(func_tuple, Anum_pg_proc_proconfig, NULL))
+	{
+		ReleaseSysCache(func_tuple);
+		return NULL;
+	}
+
+	/*
+	 * Make a temporary memory context, so that we don't leak all the stuff
+	 * that parsing might create.
+	 */
+	mycxt = AllocSetContextCreate(CurrentMemoryContext,
+								  "inline_set_returning_function",
+								  ALLOCSET_DEFAULT_SIZES);
+	oldcxt = MemoryContextSwitchTo(mycxt);
+
+	/* Fetch the function body */
+	tmp = SysCacheGetAttr(PROCOID,
+						  func_tuple,
+						  Anum_pg_proc_prosrc,
+						  &isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", func_oid);
+	src = TextDatumGetCString(tmp);
+
+	/*
+	 * Setup error traceback support for ereport().  This is so that we can
+	 * finger the function that bad information came from.
+	 */
+	callback_arg.proname = NameStr(funcform->proname);
+	callback_arg.prosrc = src;
+
+	sqlerrcontext.callback = sql_inline_error_callback;
+	sqlerrcontext.arg = (void *) &callback_arg;
+	sqlerrcontext.previous = error_context_stack;
+	error_context_stack = &sqlerrcontext;
+
+	/* If we have prosqlbody, pay attention to that not prosrc */
+	tmp = SysCacheGetAttr(PROCOID,
+						  func_tuple,
+						  Anum_pg_proc_prosqlbody,
+						  &isNull);
+	if (!isNull)
+	{
+		Node	   *n;
+
+		n = stringToNode(TextDatumGetCString(tmp));
+		if (IsA(n, List))
+			querytree_list = linitial_node(List, castNode(List, n));
+		else
+			querytree_list = list_make1(n);
+		if (list_length(querytree_list) != 1)
+			goto fail;
+		querytree = linitial(querytree_list);
+
+		/* Acquire necessary locks, then apply rewriter. */
+		AcquireRewriteLocks(querytree, true, false);
+		querytree_list = pg_rewrite_query(querytree);
+		if (list_length(querytree_list) != 1)
+			goto fail;
+		querytree = linitial(querytree_list);
+	}
+	else
+	{
+		/*
+		 * Set up to handle parameters while parsing the function body.  We
+		 * can use the FuncExpr just created as the input for
+		 * prepare_sql_fn_parse_info.
+		 */
+		pinfo = prepare_sql_fn_parse_info(func_tuple,
+										  (Node *) fexpr,
+										  fexpr->inputcollid);
+
+		/*
+		 * Parse, analyze, and rewrite (unlike inline_function(), we can't
+		 * skip rewriting here).  We can fail as soon as we find more than one
+		 * query, though.
+		 */
+		raw_parsetree_list = pg_parse_query(src);
+		if (list_length(raw_parsetree_list) != 1)
+			goto fail;
+
+		querytree_list = pg_analyze_and_rewrite_params(linitial(raw_parsetree_list),
+													   src,
+													   (ParserSetupHook) sql_fn_parser_setup,
+													   pinfo, NULL);
+		if (list_length(querytree_list) != 1)
+			goto fail;
+		querytree = linitial(querytree_list);
+	}
+
+	/*
+	 * Also resolve the actual function result tupdesc, if composite.  If the
+	 * function is just declared to return RECORD, dig the info out of the AS
+	 * clause.
+	 */
+	functypclass = get_expr_result_type((Node *) fexpr, NULL, &rettupdesc);
+	if (functypclass == TYPEFUNC_RECORD)
+		rettupdesc = BuildDescFromLists(rtfunc->funccolnames,
+										rtfunc->funccoltypes,
+										rtfunc->funccoltypmods,
+										rtfunc->funccolcollations);
+
+	/*
+	 * The single command must be a plain SELECT.
+	 */
+	if (!IsA(querytree, Query) ||
+		querytree->commandType != CMD_SELECT)
+		goto fail;
+
+	/*
+	 * Make sure the function (still) returns what it's declared to.  This
+	 * will raise an error if wrong, but that's okay since the function would
+	 * fail at runtime anyway.  Note that check_sql_fn_retval will also insert
+	 * coercions if needed to make the tlist expression(s) match the declared
+	 * type of the function.  We also ask it to insert dummy NULL columns for
+	 * any dropped columns in rettupdesc, so that the elements of the modified
+	 * tlist match up to the attribute numbers.
+	 *
+	 * If the function returns a composite type, don't inline unless the check
+	 * shows it's returning a whole tuple result; otherwise what it's
+	 * returning is a single composite column which is not what we need.
+	 */
+	if (!check_sql_fn_retval(list_make1(querytree_list),
+							 fexpr->funcresulttype, rettupdesc,
+							 true, NULL) &&
+		(functypclass == TYPEFUNC_COMPOSITE ||
+		 functypclass == TYPEFUNC_COMPOSITE_DOMAIN ||
+		 functypclass == TYPEFUNC_RECORD))
+		goto fail;				/* reject not-whole-tuple-result cases */
+
+	/*
+	 * check_sql_fn_retval might've inserted a projection step, but that's
+	 * fine; just make sure we use the upper Query.
+	 */
+	querytree = linitial_node(Query, querytree_list);
+
+	/*
+	 * Looks good --- substitute parameters into the query.
+	 */
+	querytree = substitute_actual_srf_parameters(querytree,
+												 funcform->pronargs,
+												 fexpr->args);
+
+	/*
+	 * Copy the modified query out of the temporary memory context, and clean
+	 * up.
+	 */
+	MemoryContextSwitchTo(oldcxt);
+
+	querytree = copyObject(querytree);
+
+	MemoryContextDelete(mycxt);
+	error_context_stack = sqlerrcontext.previous;
+	ReleaseSysCache(func_tuple);
+
+	/*
+	 * We don't have to fix collations here because the upper query is already
+	 * parsed, ie, the collations in the RTE are what count.
+	 */
+
+	/*
+	 * Since there is now no trace of the function in the plan tree, we must
+	 * explicitly record the plan's dependency on the function.
+	 */
+	record_plan_function_dependency(root, func_oid);
+
+	return querytree;
+
+	/* Here if func is not inlinable: release temp memory and return NULL */
+fail:
+	MemoryContextSwitchTo(oldcxt);
+	MemoryContextDelete(mycxt);
+	error_context_stack = sqlerrcontext.previous;
+	ReleaseSysCache(func_tuple);
+
+	return NULL;
+}
+
+/*
+ * Replace Param nodes by appropriate actual parameters
+ *
+ * This is just enough different from substitute_actual_parameters()
+ * that it needs its own code.
+ */
+static Query *
+substitute_actual_srf_parameters(Query *expr, int nargs, List *args)
+{
+	substitute_actual_srf_parameters_context context;
+
+	context.nargs = nargs;
+	context.args = args;
+	context.sublevels_up = 1;
+
+	return query_tree_mutator(expr,
+							  substitute_actual_srf_parameters_mutator,
+							  &context,
+							  0);
+}
+
+static Node *
+substitute_actual_srf_parameters_mutator(Node *node,
+										 substitute_actual_srf_parameters_context *context)
+{
+	Node	   *result;
+
+	if (node == NULL)
+		return NULL;
+	if (IsA(node, Query))
+	{
+		context->sublevels_up++;
+		result = (Node *) query_tree_mutator((Query *) node,
+											 substitute_actual_srf_parameters_mutator,
+											 (void *) context,
+											 0);
+		context->sublevels_up--;
+		return result;
+	}
+	if (IsA(node, Param))
+	{
+		Param	   *param = (Param *) node;
+
+		if (param->paramkind == PARAM_EXTERN)
+		{
+			if (param->paramid <= 0 || param->paramid > context->nargs)
+				elog(ERROR, "invalid paramid: %d", param->paramid);
+
+			/*
+			 * Since the parameter is being inserted into a subquery, we must
+			 * adjust levels.
+			 */
+			result = copyObject(list_nth(context->args, param->paramid - 1));
+			IncrementVarSublevelsUp(result, context->sublevels_up, 0);
+			return result;
+		}
+	}
+	return expression_tree_mutator(node,
+								   substitute_actual_srf_parameters_mutator,
+								   (void *) context);
+}
+
+/*
+ * pull_paramids
+ *		Returns a Bitmapset containing the paramids of all Params in 'expr'.
+ */
+Bitmapset *
+pull_paramids(Expr *expr)
+{
+	Bitmapset  *result = NULL;
+
+	(void) pull_paramids_walker((Node *) expr, &result);
+
+	return result;
+}
+
+static bool
+pull_paramids_walker(Node *node, Bitmapset **context)
+{
+	if (node == NULL)
+		return false;
+	if (IsA(node, Param))
+	{
+		Param	   *param = (Param *)node;
+
+		*context = bms_add_member(*context, param->paramid);
+		return false;
+	}
+	return expression_tree_walker(node, pull_paramids_walker,
+								  (void *) context);
+}