Arrange to "inline" SQL functions that appear in a query's FROM clause,

are declared to return set, and consist of just a single SELECT.  We
can replace the FROM-item with a sub-SELECT and then optimize much as
if we were dealing with a view.  Patch from Richard Rowell, cleaned up
by me.

src/backend/catalog/pg_proc.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/pg_proc.c,v 1.148 2008/01/01 19:45:48 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/pg_proc.c,v 1.149 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -601,7 +601,8 @@ fmgr_sql_validator(PG_FUNCTION_ARGS)
 												  proc->proargtypes.values,
 												  proc->pronargs);
 			(void) check_sql_fn_retval(funcoid, proc->prorettype,
-									   querytree_list, NULL);
+									   querytree_list,
+									   false, NULL);
 		}
 		else
 			querytree_list = pg_parse_query(prosrc);

src/backend/executor/functions.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.120 2008/01/01 19:45:49 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.121 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,6 +20,7 @@
 #include "commands/trigger.h"
 #include "executor/functions.h"
 #include "funcapi.h"
+#include "nodes/makefuncs.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
 #include "tcop/tcopprot.h"
@@ -269,6 +270,7 @@ init_sql_fcache(FmgrInfo *finfo)
 	fcache->returnsTuple = check_sql_fn_retval(foid,
 											   rettype,
 											   queryTree_list,
+											   false,
 											   &fcache->junkFilter);
 
 	/* Finally, plan the queries */
@@ -856,7 +858,9 @@ ShutdownSQLFunction(Datum arg)
  *
  * The return value of a sql function is the value returned by
  * the final query in the function.  We do some ad-hoc type checking here
- * to be sure that the user is returning the type he claims.
+ * to be sure that the user is returning the type he claims.  There are
+ * also a couple of strange-looking features to assist callers in dealing
+ * with allowed special cases, such as binary-compatible result types.
  *
  * For a polymorphic function the passed rettype must be the actual resolved
  * output type of the function; we should never see a polymorphic pseudotype
@@ -868,6 +872,10 @@ ShutdownSQLFunction(Datum arg)
  * allow "SELECT rowtype_expression", this may be false even when the declared
  * function return type is a rowtype.
  *
+ * If insertRelabels is true, then binary-compatible cases are dealt with
+ * by actually inserting RelabelType nodes into the final SELECT; obviously
+ * the caller must pass a parsetree that it's okay to modify in this case.
+ *
  * If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
  * to convert the function's tuple result to the correct output tuple type.
  * Whenever the result value is false (ie, the function isn't returning a
@@ -875,6 +883,7 @@ ShutdownSQLFunction(Datum arg)
  */
 bool
 check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
+					bool insertRelabels,
 					JunkFilter **junkFilter)
 {
 	Query	   *parse;
@@ -945,10 +954,12 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 		rettype == VOIDOID)
 	{
 		/*
-		 * For scalar-type returns, the target list should have exactly one
+		 * For scalar-type returns, the target list must have exactly one
-		 * entry, and its type should agree with what the user declared. (As
+		 * non-junk entry, and its type must agree with what the user
-		 * of Postgres 7.2, we accept binary-compatible types too.)
+		 * declared; except we allow binary-compatible types too.
 		 */
+		TargetEntry *tle;
+
 		if (tlistlen != 1)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
@@ -956,7 +967,11 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 					format_type_be(rettype)),
 				 errdetail("Final SELECT must return exactly one column.")));
 
-		restype = exprType((Node *) ((TargetEntry *) linitial(tlist))->expr);
+		/* We assume here that non-junk TLEs must come first in tlists */
+		tle = (TargetEntry *) linitial(tlist);
+		Assert(!tle->resjunk);
+
+		restype = exprType((Node *) tle->expr);
 		if (!IsBinaryCoercible(restype, rettype))
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
@@ -964,6 +979,11 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 					format_type_be(rettype)),
 					 errdetail("Actual return type is %s.",
 							   format_type_be(restype))));
+		if (insertRelabels && restype != rettype)
+			tle->expr = (Expr *) makeRelabelType(tle->expr,
+												 rettype,
+												 -1,
+												 COERCE_DONTCARE);
 	}
 	else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
 	{
@@ -977,14 +997,24 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 		 * If the target list is of length 1, and the type of the varnode in
 		 * the target list matches the declared return type, this is okay.
 		 * This can happen, for example, where the body of the function is
-		 * 'SELECT func2()', where func2 has the same return type as the
+		 * 'SELECT func2()', where func2 has the same composite return type
-		 * function that's calling it.
+		 * as the function that's calling it.
 		 */
 		if (tlistlen == 1)
 		{
-			restype = exprType((Node *) ((TargetEntry *) linitial(tlist))->expr);
+			TargetEntry *tle = (TargetEntry *) linitial(tlist);
+
+			Assert(!tle->resjunk);
+			restype = exprType((Node *) tle->expr);
 			if (IsBinaryCoercible(restype, rettype))
+			{
+				if (insertRelabels && restype != rettype)
+					tle->expr = (Expr *) makeRelabelType(tle->expr,
+														 rettype,
+														 -1,
+														 COERCE_DONTCARE);
 				return false;	/* NOT returning whole tuple */
+			}
 		}
 
 		/* Is the rowtype fixed, or determined only at runtime? */
@@ -1043,6 +1073,11 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 								   format_type_be(tletype),
 								   format_type_be(atttype),
 								   tuplogcols)));
+			if (insertRelabels && tletype != atttype)
+				tle->expr = (Expr *) makeRelabelType(tle->expr,
+													 atttype,
+													 -1,
+													 COERCE_DONTCARE);
 		}
 
 		for (;;)
@@ -1070,14 +1105,6 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 		/* Report that we are returning entire tuple result */
 		return true;
 	}
-	else if (IsPolymorphicType(rettype))
-	{
-		/* This should already have been caught ... */
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-				 errmsg("cannot determine result data type"),
-				 errdetail("A function returning a polymorphic type must have at least one polymorphic argument.")));
-	}
 	else
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.226 2008/01/01 19:45:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.227 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -253,13 +253,20 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	/*
 	 * Look for IN clauses at the top level of WHERE, and transform them into
 	 * joins.  Note that this step only handles IN clauses originally at top
-	 * level of WHERE; if we pull up any subqueries in the next step, their
+	 * level of WHERE; if we pull up any subqueries below, their INs are
-	 * INs are processed just before pulling them up.
+	 * processed just before pulling them up.
 	 */
 	if (parse->hasSubLinks)
 		parse->jointree->quals = pull_up_IN_clauses(root,
 													parse->jointree->quals);
 
+	/*
+	 * Scan the rangetable for set-returning functions, and inline them
+	 * if possible (producing subqueries that might get pulled up next).
+	 * Recursion issues here are handled in the same way as for IN clauses.
+	 */
+	inline_set_returning_functions(root);
+
 	/*
 	 * Check to see if any subqueries in the rangetable can be merged into
 	 * this query.

src/backend/optimizer/prep/prepjointree.c

@@ -5,6 +5,7 @@
  *
  * NOTE: the intended sequence for invoking these operations is
  *		pull_up_IN_clauses
+ *		inline_set_returning_functions
  *		pull_up_subqueries
  *		do expression preprocessing (including flattening JOIN alias vars)
  *		reduce_outer_joins
@@ -15,7 +16,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.49 2008/01/01 19:45:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.50 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -124,6 +125,52 @@ pull_up_IN_clauses(PlannerInfo *root, Node *node)
 	return node;
 }
 
+/*
+ * inline_set_returning_functions
+ *		Attempt to "inline" set-returning functions in the FROM clause.
+ *
+ * If an RTE_FUNCTION rtable entry invokes a set-returning function that
+ * contains just a simple SELECT, we can convert the rtable entry to an
+ * RTE_SUBQUERY entry exposing the SELECT directly.  This is especially
+ * useful if the subquery can then be "pulled up" for further optimization,
+ * but we do it even if not, to reduce executor overhead.
+ *
+ * This has to be done before we have started to do any optimization of
+ * subqueries, else any such steps wouldn't get applied to subqueries
+ * obtained via inlining.  However, we do it after pull_up_IN_clauses
+ * so that we can inline any functions used in IN subselects.
+ *
+ * Like most of the planner, this feels free to scribble on its input data
+ * structure.
+ */
+void
+inline_set_returning_functions(PlannerInfo *root)
+{
+	ListCell   *rt;
+
+	foreach(rt, root->parse->rtable)
+	{
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
+
+		if (rte->rtekind == RTE_FUNCTION)
+		{
+			Query  *funcquery;
+
+			/* Check safety of expansion, and expand if possible */
+			funcquery = inline_set_returning_function(root, rte->funcexpr);
+			if (funcquery)
+			{
+				/* Successful expansion, replace the rtable entry */
+				rte->rtekind = RTE_SUBQUERY;
+				rte->subquery = funcquery;
+				rte->funcexpr = NULL;
+				rte->funccoltypes = NIL;
+				rte->funccoltypmods = NIL;
+			}
+		}
+	}
+}
+
 /*
  * pull_up_subqueries
  *		Look for subqueries in the rangetable that can be pulled up into
@@ -296,6 +343,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->query_level = root->query_level;
 	subroot->planner_cxt = CurrentMemoryContext;
 	subroot->init_plans = NIL;
+	subroot->eq_classes = NIL;
 	subroot->in_info_list = NIL;
 	subroot->append_rel_list = NIL;
 
@@ -307,6 +355,11 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 		subquery->jointree->quals = pull_up_IN_clauses(subroot,
 												  subquery->jointree->quals);
 
+	/*
+	 * Similarly, inline any set-returning functions in its rangetable.
+	 */
+	inline_set_returning_functions(subroot);
+
 	/*
 	 * Recursively pull up the subquery's subqueries, so that
 	 * pull_up_subqueries' processing is complete for its jointree and

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.254 2008/01/11 18:39:40 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.255 2008/03/18 22:04:14 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -38,6 +38,7 @@
 #include "parser/parse_clause.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
+#include "rewrite/rewriteManip.h"
 #include "tcop/tcopprot.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
@@ -63,6 +64,13 @@ typedef struct
 	int		   *usecounts;
 } substitute_actual_parameters_context;
 
+typedef struct
+{
+	int			nargs;
+	List	   *args;
+	int			sublevels_up;
+} substitute_actual_srf_parameters_context;
+
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool count_agg_clauses_walker(Node *node, AggClauseCounts *counts);
 static bool expression_returns_set_walker(Node *node, void *context);
@@ -100,6 +108,10 @@ static Node *substitute_actual_parameters_mutator(Node *node,
 							  substitute_actual_parameters_context *context);
 static void sql_inline_error_callback(void *arg);
 static Expr *evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod);
+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);
 
 
 /*****************************************************************************
@@ -3027,18 +3039,26 @@ inline_function(Oid funcid, Oid result_type, List *args,
 		list_length(querytree->targetList) != 1)
 		goto fail;
 
-	newexpr = (Node *) ((TargetEntry *) linitial(querytree->targetList))->expr;
-
 	/*
 	 * 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 we do not try this until we have verified
+	 * fail at runtime anyway.  Note that check_sql_fn_retval will also insert
-	 * that no rewriting was needed; that's probably not important, but let's
+	 * a RelabelType if needed to make the tlist expression match the declared
-	 * be careful.
+	 * 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.
 	 */
-	if (check_sql_fn_retval(funcid, result_type, list_make1(querytree), NULL))
+	if (check_sql_fn_retval(funcid, result_type, list_make1(querytree),
+							true, NULL))
 		goto fail;				/* reject whole-tuple-result cases */
 
+	/* Now we can grab the tlist expression */
+	newexpr = (Node *) ((TargetEntry *) linitial(querytree->targetList))->expr;
+
+	/* Assert that check_sql_fn_retval did the right thing */
+	Assert(exprType(newexpr) == result_type);
+
 	/*
 	 * Additional validity checks on the expression.  It mustn't return a set,
 	 * and it mustn't be more volatile than the surrounding function (this is
@@ -3122,21 +3142,6 @@ inline_function(Oid funcid, Oid result_type, List *args,
 
 	MemoryContextDelete(mycxt);
 
-	/*
-	 * Since check_sql_fn_retval allows binary-compatibility cases, the
-	 * expression we now have might return some type that's only binary
-	 * compatible with the original expression result type.  To avoid
-	 * confusing matters, insert a RelabelType in such cases.
-	 */
-	if (exprType(newexpr) != result_type)
-	{
-		Assert(IsBinaryCoercible(exprType(newexpr), result_type));
-		newexpr = (Node *) makeRelabelType((Expr *) newexpr,
-										   result_type,
-										   -1,
-										   COERCE_IMPLICIT_CAST);
-	}
-
 	/*
 	 * Recursively try to simplify the modified expression.  Here we must add
 	 * the current function to the context list of active functions.
@@ -3307,6 +3312,285 @@ evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod)
 }
 
 
+/*
+ * inline_set_returning_function
+ *		Attempt to "inline" a set-returning function in the FROM clause.
+ *
+ * "node" is the expression from 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.
+ *
+ * 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, Node *node)
+{
+	FuncExpr   *fexpr;
+	HeapTuple	func_tuple;
+	Form_pg_proc funcform;
+	Oid		   *argtypes;
+	char	   *src;
+	Datum		tmp;
+	bool		isNull;
+	MemoryContext oldcxt;
+	MemoryContext mycxt;
+	ErrorContextCallback sqlerrcontext;
+	List	   *raw_parsetree_list;
+	List	   *querytree_list;
+	Query	   *querytree;
+	int			i;
+
+	/*
+	 * 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 FROM item isn't a simple FuncExpr */
+	if (node == NULL || !IsA(node, FuncExpr))
+		return NULL;
+	fexpr = (FuncExpr *) node;
+
+	/*
+	 * 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;
+
+	/* Fail if function returns RECORD ... we don't have enough context */
+	if (fexpr->funcresulttype == RECORDOID)
+		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(fexpr->funcid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
+		return NULL;
+
+	/*
+	 * OK, let's take a look at the function's pg_proc entry.
+	 */
+	func_tuple = SearchSysCache(PROCOID,
+								ObjectIdGetDatum(fexpr->funcid),
+								0, 0, 0);
+	if (!HeapTupleIsValid(func_tuple))
+		elog(ERROR, "cache lookup failed for function %u", fexpr->funcid);
+	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.  (The nargs check is just
+	 * paranoia, ditto rechecking proretset.)
+	 */
+	if (funcform->prolang != SQLlanguageId ||
+		funcform->proisstrict ||
+		funcform->provolatile == PROVOLATILE_VOLATILE ||
+		funcform->prosecdef ||
+		!funcform->proretset ||
+		!heap_attisnull(func_tuple, Anum_pg_proc_proconfig) ||
+		funcform->pronargs != list_length(fexpr->args))
+	{
+		ReleaseSysCache(func_tuple);
+		return NULL;
+	}
+
+	/*
+	 * Setup error traceback support for ereport().  This is so that we can
+	 * finger the function that bad information came from.
+	 */
+	sqlerrcontext.callback = sql_inline_error_callback;
+	sqlerrcontext.arg = func_tuple;
+	sqlerrcontext.previous = error_context_stack;
+	error_context_stack = &sqlerrcontext;
+
+	/*
+	 * 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_MINSIZE,
+								  ALLOCSET_DEFAULT_INITSIZE,
+								  ALLOCSET_DEFAULT_MAXSIZE);
+	oldcxt = MemoryContextSwitchTo(mycxt);
+
+	/* Check for polymorphic arguments, and substitute actual arg types */
+	argtypes = (Oid *) palloc(funcform->pronargs * sizeof(Oid));
+	memcpy(argtypes, funcform->proargtypes.values,
+		   funcform->pronargs * sizeof(Oid));
+	for (i = 0; i < funcform->pronargs; i++)
+	{
+		if (IsPolymorphicType(argtypes[i]))
+		{
+			argtypes[i] = exprType((Node *) list_nth(fexpr->args, i));
+		}
+	}
+
+	/* Fetch and parse the function body */
+	tmp = SysCacheGetAttr(PROCOID,
+						  func_tuple,
+						  Anum_pg_proc_prosrc,
+						  &isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", fexpr->funcid);
+	src = DatumGetCString(DirectFunctionCall1(textout, tmp));
+
+	/*
+	 * 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(linitial(raw_parsetree_list), src,
+							  argtypes, funcform->pronargs);
+	if (list_length(querytree_list) != 1)
+		goto fail;
+	querytree = linitial(querytree_list);
+
+	/*
+	 * The single command must be a regular results-returning SELECT.
+	 */
+	if (!IsA(querytree, Query) ||
+		querytree->commandType != CMD_SELECT ||
+		querytree->utilityStmt ||
+		querytree->intoClause)
+		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
+	 * RelabelType(s) if needed to make the tlist expression(s) match the
+	 * declared type of the function.
+	 *
+	 * 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(fexpr->funcid, fexpr->funcresulttype,
+							 querytree_list,
+							 true, NULL) &&
+		get_typtype(fexpr->funcresulttype) == TYPTYPE_COMPOSITE)
+		goto fail;				/* reject not-whole-tuple-result cases */
+
+	/*
+	 * 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);
+
+	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);
+}
+
+
 /*
  * Standard expression-tree walking support
  *

src/include/executor/functions.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/executor/functions.h,v 1.30 2008/01/01 19:45:57 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/executor/functions.h,v 1.31 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,6 +21,7 @@ extern Datum fmgr_sql(PG_FUNCTION_ARGS);
 
 extern bool check_sql_fn_retval(Oid func_id, Oid rettype,
 					List *queryTreeList,
+					bool insertRelabels,
 					JunkFilter **junkFilter);
 
 #endif   /* FUNCTIONS_H */

src/include/optimizer/clauses.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/clauses.h,v 1.88 2008/01/01 19:45:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/clauses.h,v 1.89 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -79,6 +79,8 @@ extern Node *eval_const_expressions(Node *node);
 
 extern Node *estimate_expression_value(PlannerInfo *root, Node *node);
 
+extern Query *inline_set_returning_function(PlannerInfo *root, Node *node);
+
 extern bool expression_tree_walker(Node *node, bool (*walker) (),
 											   void *context);
 extern Node *expression_tree_mutator(Node *node, Node *(*mutator) (),

src/include/optimizer/prep.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/prep.h,v 1.59 2008/01/01 19:45:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/prep.h,v 1.60 2008/03/18 22:04:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,6 +22,7 @@
  * prototypes for prepjointree.c
  */
 extern Node *pull_up_IN_clauses(PlannerInfo *root, Node *node);
+extern void inline_set_returning_functions(PlannerInfo *root);
 extern Node *pull_up_subqueries(PlannerInfo *root, Node *jtnode,
 				   bool below_outer_join, bool append_rel_member);
 extern void reduce_outer_joins(PlannerInfo *root);