Adding upstream version 14.5.upstream/14.5upstream

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

1 files changed, 2103 insertions, 0 deletions

diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
new file mode 100644
index 0000000..296e54e
--- /dev/null
+++ b/src/backend/executor/functions.c
@@ -0,0 +1,2103 @@
+/*-------------------------------------------------------------------------
+ *
+ * functions.c
+ *	  Execution of SQL-language functions
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/executor/functions.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "access/xact.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
+#include "executor/functions.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_collate.h"
+#include "parser/parse_func.h"
+#include "rewrite/rewriteHandler.h"
+#include "storage/proc.h"
+#include "tcop/utility.h"
+#include "utils/builtins.h"
+#include "utils/datum.h"
+#include "utils/lsyscache.h"
+#include "utils/memutils.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+
+
+/*
+ * Specialized DestReceiver for collecting query output in a SQL function
+ */
+typedef struct
+{
+	DestReceiver pub;			/* publicly-known function pointers */
+	Tuplestorestate *tstore;	/* where to put result tuples */
+	MemoryContext cxt;			/* context containing tstore */
+	JunkFilter *filter;			/* filter to convert tuple type */
+} DR_sqlfunction;
+
+/*
+ * We have an execution_state record for each query in a function.  Each
+ * record contains a plantree for its query.  If the query is currently in
+ * F_EXEC_RUN state then there's a QueryDesc too.
+ *
+ * The "next" fields chain together all the execution_state records generated
+ * from a single original parsetree.  (There will only be more than one in
+ * case of rule expansion of the original parsetree.)
+ */
+typedef enum
+{
+	F_EXEC_START, F_EXEC_RUN, F_EXEC_DONE
+} ExecStatus;
+
+typedef struct execution_state
+{
+	struct execution_state *next;
+	ExecStatus	status;
+	bool		setsResult;		/* true if this query produces func's result */
+	bool		lazyEval;		/* true if should fetch one row at a time */
+	PlannedStmt *stmt;			/* plan for this query */
+	QueryDesc  *qd;				/* null unless status == RUN */
+} execution_state;
+
+
+/*
+ * An SQLFunctionCache record is built during the first call,
+ * and linked to from the fn_extra field of the FmgrInfo struct.
+ *
+ * Note that currently this has only the lifespan of the calling query.
+ * Someday we should rewrite this code to use plancache.c to save parse/plan
+ * results for longer than that.
+ *
+ * Physically, though, the data has the lifespan of the FmgrInfo that's used
+ * to call the function, and there are cases (particularly with indexes)
+ * where the FmgrInfo might survive across transactions.  We cannot assume
+ * that the parse/plan trees are good for longer than the (sub)transaction in
+ * which parsing was done, so we must mark the record with the LXID/subxid of
+ * its creation time, and regenerate everything if that's obsolete.  To avoid
+ * memory leakage when we do have to regenerate things, all the data is kept
+ * in a sub-context of the FmgrInfo's fn_mcxt.
+ */
+typedef struct
+{
+	char	   *fname;			/* function name (for error msgs) */
+	char	   *src;			/* function body text (for error msgs) */
+
+	SQLFunctionParseInfoPtr pinfo;	/* data for parser callback hooks */
+
+	Oid			rettype;		/* actual return type */
+	int16		typlen;			/* length of the return type */
+	bool		typbyval;		/* true if return type is pass by value */
+	bool		returnsSet;		/* true if returning multiple rows */
+	bool		returnsTuple;	/* true if returning whole tuple result */
+	bool		shutdown_reg;	/* true if registered shutdown callback */
+	bool		readonly_func;	/* true to run in "read only" mode */
+	bool		lazyEval;		/* true if using lazyEval for result query */
+
+	ParamListInfo paramLI;		/* Param list representing current args */
+
+	Tuplestorestate *tstore;	/* where we accumulate result tuples */
+
+	JunkFilter *junkFilter;		/* will be NULL if function returns VOID */
+
+	/*
+	 * func_state is a List of execution_state records, each of which is the
+	 * first for its original parsetree, with any additional records chained
+	 * to it via the "next" fields.  This sublist structure is needed to keep
+	 * track of where the original query boundaries are.
+	 */
+	List	   *func_state;
+
+	MemoryContext fcontext;		/* memory context holding this struct and all
+								 * subsidiary data */
+
+	LocalTransactionId lxid;	/* lxid in which cache was made */
+	SubTransactionId subxid;	/* subxid in which cache was made */
+} SQLFunctionCache;
+
+typedef SQLFunctionCache *SQLFunctionCachePtr;
+
+
+/* non-export function prototypes */
+static Node *sql_fn_param_ref(ParseState *pstate, ParamRef *pref);
+static Node *sql_fn_post_column_ref(ParseState *pstate,
+									ColumnRef *cref, Node *var);
+static Node *sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
+							   int paramno, int location);
+static Node *sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
+									   const char *paramname, int location);
+static List *init_execution_state(List *queryTree_list,
+								  SQLFunctionCachePtr fcache,
+								  bool lazyEvalOK);
+static void init_sql_fcache(FunctionCallInfo fcinfo, Oid collation, bool lazyEvalOK);
+static void postquel_start(execution_state *es, SQLFunctionCachePtr fcache);
+static bool postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache);
+static void postquel_end(execution_state *es);
+static void postquel_sub_params(SQLFunctionCachePtr fcache,
+								FunctionCallInfo fcinfo);
+static Datum postquel_get_single_result(TupleTableSlot *slot,
+										FunctionCallInfo fcinfo,
+										SQLFunctionCachePtr fcache,
+										MemoryContext resultcontext);
+static void sql_exec_error_callback(void *arg);
+static void ShutdownSQLFunction(Datum arg);
+static bool coerce_fn_result_column(TargetEntry *src_tle,
+									Oid res_type, int32 res_typmod,
+									bool tlist_is_modifiable,
+									List **upper_tlist,
+									bool *upper_tlist_nontrivial);
+static void sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
+static bool sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self);
+static void sqlfunction_shutdown(DestReceiver *self);
+static void sqlfunction_destroy(DestReceiver *self);
+
+
+/*
+ * Prepare the SQLFunctionParseInfo struct for parsing a SQL function body
+ *
+ * This includes resolving actual types of polymorphic arguments.
+ *
+ * call_expr can be passed as NULL, but then we will fail if there are any
+ * polymorphic arguments.
+ */
+SQLFunctionParseInfoPtr
+prepare_sql_fn_parse_info(HeapTuple procedureTuple,
+						  Node *call_expr,
+						  Oid inputCollation)
+{
+	SQLFunctionParseInfoPtr pinfo;
+	Form_pg_proc procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
+	int			nargs;
+
+	pinfo = (SQLFunctionParseInfoPtr) palloc0(sizeof(SQLFunctionParseInfo));
+
+	/* Function's name (only) can be used to qualify argument names */
+	pinfo->fname = pstrdup(NameStr(procedureStruct->proname));
+
+	/* Save the function's input collation */
+	pinfo->collation = inputCollation;
+
+	/*
+	 * Copy input argument types from the pg_proc entry, then resolve any
+	 * polymorphic types.
+	 */
+	pinfo->nargs = nargs = procedureStruct->pronargs;
+	if (nargs > 0)
+	{
+		Oid		   *argOidVect;
+		int			argnum;
+
+		argOidVect = (Oid *) palloc(nargs * sizeof(Oid));
+		memcpy(argOidVect,
+			   procedureStruct->proargtypes.values,
+			   nargs * sizeof(Oid));
+
+		for (argnum = 0; argnum < nargs; argnum++)
+		{
+			Oid			argtype = argOidVect[argnum];
+
+			if (IsPolymorphicType(argtype))
+			{
+				argtype = get_call_expr_argtype(call_expr, argnum);
+				if (argtype == InvalidOid)
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("could not determine actual type of argument declared %s",
+									format_type_be(argOidVect[argnum]))));
+				argOidVect[argnum] = argtype;
+			}
+		}
+
+		pinfo->argtypes = argOidVect;
+	}
+
+	/*
+	 * Collect names of arguments, too, if any
+	 */
+	if (nargs > 0)
+	{
+		Datum		proargnames;
+		Datum		proargmodes;
+		int			n_arg_names;
+		bool		isNull;
+
+		proargnames = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
+									  Anum_pg_proc_proargnames,
+									  &isNull);
+		if (isNull)
+			proargnames = PointerGetDatum(NULL);	/* just to be sure */
+
+		proargmodes = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
+									  Anum_pg_proc_proargmodes,
+									  &isNull);
+		if (isNull)
+			proargmodes = PointerGetDatum(NULL);	/* just to be sure */
+
+		n_arg_names = get_func_input_arg_names(proargnames, proargmodes,
+											   &pinfo->argnames);
+
+		/* Paranoia: ignore the result if too few array entries */
+		if (n_arg_names < nargs)
+			pinfo->argnames = NULL;
+	}
+	else
+		pinfo->argnames = NULL;
+
+	return pinfo;
+}
+
+/*
+ * Parser setup hook for parsing a SQL function body.
+ */
+void
+sql_fn_parser_setup(struct ParseState *pstate, SQLFunctionParseInfoPtr pinfo)
+{
+	pstate->p_pre_columnref_hook = NULL;
+	pstate->p_post_columnref_hook = sql_fn_post_column_ref;
+	pstate->p_paramref_hook = sql_fn_param_ref;
+	/* no need to use p_coerce_param_hook */
+	pstate->p_ref_hook_state = (void *) pinfo;
+}
+
+/*
+ * sql_fn_post_column_ref		parser callback for ColumnRefs
+ */
+static Node *
+sql_fn_post_column_ref(ParseState *pstate, ColumnRef *cref, Node *var)
+{
+	SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
+	int			nnames;
+	Node	   *field1;
+	Node	   *subfield = NULL;
+	const char *name1;
+	const char *name2 = NULL;
+	Node	   *param;
+
+	/*
+	 * Never override a table-column reference.  This corresponds to
+	 * considering the parameter names to appear in a scope outside the
+	 * individual SQL commands, which is what we want.
+	 */
+	if (var != NULL)
+		return NULL;
+
+	/*----------
+	 * The allowed syntaxes are:
+	 *
+	 * A		A = parameter name
+	 * A.B		A = function name, B = parameter name
+	 *			OR: A = record-typed parameter name, B = field name
+	 *			(the first possibility takes precedence)
+	 * A.B.C	A = function name, B = record-typed parameter name,
+	 *			C = field name
+	 * A.*		Whole-row reference to composite parameter A.
+	 * A.B.*	Same, with A = function name, B = parameter name
+	 *
+	 * Here, it's sufficient to ignore the "*" in the last two cases --- the
+	 * main parser will take care of expanding the whole-row reference.
+	 *----------
+	 */
+	nnames = list_length(cref->fields);
+
+	if (nnames > 3)
+		return NULL;
+
+	if (IsA(llast(cref->fields), A_Star))
+		nnames--;
+
+	field1 = (Node *) linitial(cref->fields);
+	Assert(IsA(field1, String));
+	name1 = strVal(field1);
+	if (nnames > 1)
+	{
+		subfield = (Node *) lsecond(cref->fields);
+		Assert(IsA(subfield, String));
+		name2 = strVal(subfield);
+	}
+
+	if (nnames == 3)
+	{
+		/*
+		 * Three-part name: if the first part doesn't match the function name,
+		 * we can fail immediately. Otherwise, look up the second part, and
+		 * take the third part to be a field reference.
+		 */
+		if (strcmp(name1, pinfo->fname) != 0)
+			return NULL;
+
+		param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
+
+		subfield = (Node *) lthird(cref->fields);
+		Assert(IsA(subfield, String));
+	}
+	else if (nnames == 2 && strcmp(name1, pinfo->fname) == 0)
+	{
+		/*
+		 * Two-part name with first part matching function name: first see if
+		 * second part matches any parameter name.
+		 */
+		param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
+
+		if (param)
+		{
+			/* Yes, so this is a parameter reference, no subfield */
+			subfield = NULL;
+		}
+		else
+		{
+			/* No, so try to match as parameter name and subfield */
+			param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
+		}
+	}
+	else
+	{
+		/* Single name, or parameter name followed by subfield */
+		param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
+	}
+
+	if (!param)
+		return NULL;			/* No match */
+
+	if (subfield)
+	{
+		/*
+		 * Must be a reference to a field of a composite parameter; otherwise
+		 * ParseFuncOrColumn will return NULL, and we'll fail back at the
+		 * caller.
+		 */
+		param = ParseFuncOrColumn(pstate,
+								  list_make1(subfield),
+								  list_make1(param),
+								  pstate->p_last_srf,
+								  NULL,
+								  false,
+								  cref->location);
+	}
+
+	return param;
+}
+
+/*
+ * sql_fn_param_ref		parser callback for ParamRefs ($n symbols)
+ */
+static Node *
+sql_fn_param_ref(ParseState *pstate, ParamRef *pref)
+{
+	SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
+	int			paramno = pref->number;
+
+	/* Check parameter number is valid */
+	if (paramno <= 0 || paramno > pinfo->nargs)
+		return NULL;			/* unknown parameter number */
+
+	return sql_fn_make_param(pinfo, paramno, pref->location);
+}
+
+/*
+ * sql_fn_make_param		construct a Param node for the given paramno
+ */
+static Node *
+sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
+				  int paramno, int location)
+{
+	Param	   *param;
+
+	param = makeNode(Param);
+	param->paramkind = PARAM_EXTERN;
+	param->paramid = paramno;
+	param->paramtype = pinfo->argtypes[paramno - 1];
+	param->paramtypmod = -1;
+	param->paramcollid = get_typcollation(param->paramtype);
+	param->location = location;
+
+	/*
+	 * If we have a function input collation, allow it to override the
+	 * type-derived collation for parameter symbols.  (XXX perhaps this should
+	 * not happen if the type collation is not default?)
+	 */
+	if (OidIsValid(pinfo->collation) && OidIsValid(param->paramcollid))
+		param->paramcollid = pinfo->collation;
+
+	return (Node *) param;
+}
+
+/*
+ * Search for a function parameter of the given name; if there is one,
+ * construct and return a Param node for it.  If not, return NULL.
+ * Helper function for sql_fn_post_column_ref.
+ */
+static Node *
+sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
+						  const char *paramname, int location)
+{
+	int			i;
+
+	if (pinfo->argnames == NULL)
+		return NULL;
+
+	for (i = 0; i < pinfo->nargs; i++)
+	{
+		if (pinfo->argnames[i] && strcmp(pinfo->argnames[i], paramname) == 0)
+			return sql_fn_make_param(pinfo, i + 1, location);
+	}
+
+	return NULL;
+}
+
+/*
+ * Set up the per-query execution_state records for a SQL function.
+ *
+ * The input is a List of Lists of parsed and rewritten, but not planned,
+ * querytrees.  The sublist structure denotes the original query boundaries.
+ */
+static List *
+init_execution_state(List *queryTree_list,
+					 SQLFunctionCachePtr fcache,
+					 bool lazyEvalOK)
+{
+	List	   *eslist = NIL;
+	execution_state *lasttages = NULL;
+	ListCell   *lc1;
+
+	foreach(lc1, queryTree_list)
+	{
+		List	   *qtlist = lfirst_node(List, lc1);
+		execution_state *firstes = NULL;
+		execution_state *preves = NULL;
+		ListCell   *lc2;
+
+		foreach(lc2, qtlist)
+		{
+			Query	   *queryTree = lfirst_node(Query, lc2);
+			PlannedStmt *stmt;
+			execution_state *newes;
+
+			/* Plan the query if needed */
+			if (queryTree->commandType == CMD_UTILITY)
+			{
+				/* Utility commands require no planning. */
+				stmt = makeNode(PlannedStmt);
+				stmt->commandType = CMD_UTILITY;
+				stmt->canSetTag = queryTree->canSetTag;
+				stmt->utilityStmt = queryTree->utilityStmt;
+				stmt->stmt_location = queryTree->stmt_location;
+				stmt->stmt_len = queryTree->stmt_len;
+			}
+			else
+				stmt = pg_plan_query(queryTree,
+									 fcache->src,
+									 CURSOR_OPT_PARALLEL_OK,
+									 NULL);
+
+			/*
+			 * Precheck all commands for validity in a function.  This should
+			 * generally match the restrictions spi.c applies.
+			 */
+			if (stmt->commandType == CMD_UTILITY)
+			{
+				if (IsA(stmt->utilityStmt, CopyStmt) &&
+					((CopyStmt *) stmt->utilityStmt)->filename == NULL)
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("cannot COPY to/from client in an SQL function")));
+
+				if (IsA(stmt->utilityStmt, TransactionStmt))
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					/* translator: %s is a SQL statement name */
+							 errmsg("%s is not allowed in an SQL function",
+									CreateCommandName(stmt->utilityStmt))));
+			}
+
+			if (fcache->readonly_func && !CommandIsReadOnly(stmt))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				/* translator: %s is a SQL statement name */
+						 errmsg("%s is not allowed in a non-volatile function",
+								CreateCommandName((Node *) stmt))));
+
+			/* OK, build the execution_state for this query */
+			newes = (execution_state *) palloc(sizeof(execution_state));
+			if (preves)
+				preves->next = newes;
+			else
+				firstes = newes;
+
+			newes->next = NULL;
+			newes->status = F_EXEC_START;
+			newes->setsResult = false;	/* might change below */
+			newes->lazyEval = false;	/* might change below */
+			newes->stmt = stmt;
+			newes->qd = NULL;
+
+			if (queryTree->canSetTag)
+				lasttages = newes;
+
+			preves = newes;
+		}
+
+		eslist = lappend(eslist, firstes);
+	}
+
+	/*
+	 * Mark the last canSetTag query as delivering the function result; then,
+	 * if it is a plain SELECT, mark it for lazy evaluation. If it's not a
+	 * SELECT we must always run it to completion.
+	 *
+	 * Note: at some point we might add additional criteria for whether to use
+	 * lazy eval.  However, we should prefer to use it whenever the function
+	 * doesn't return set, since fetching more than one row is useless in that
+	 * case.
+	 *
+	 * Note: don't set setsResult if the function returns VOID, as evidenced
+	 * by not having made a junkfilter.  This ensures we'll throw away any
+	 * output from the last statement in such a function.
+	 */
+	if (lasttages && fcache->junkFilter)
+	{
+		lasttages->setsResult = true;
+		if (lazyEvalOK &&
+			lasttages->stmt->commandType == CMD_SELECT &&
+			!lasttages->stmt->hasModifyingCTE)
+			fcache->lazyEval = lasttages->lazyEval = true;
+	}
+
+	return eslist;
+}
+
+/*
+ * Initialize the SQLFunctionCache for a SQL function
+ */
+static void
+init_sql_fcache(FunctionCallInfo fcinfo, Oid collation, bool lazyEvalOK)
+{
+	FmgrInfo   *finfo = fcinfo->flinfo;
+	Oid			foid = finfo->fn_oid;
+	MemoryContext fcontext;
+	MemoryContext oldcontext;
+	Oid			rettype;
+	TupleDesc	rettupdesc;
+	HeapTuple	procedureTuple;
+	Form_pg_proc procedureStruct;
+	SQLFunctionCachePtr fcache;
+	List	   *queryTree_list;
+	List	   *resulttlist;
+	ListCell   *lc;
+	Datum		tmp;
+	bool		isNull;
+
+	/*
+	 * Create memory context that holds all the SQLFunctionCache data.  It
+	 * must be a child of whatever context holds the FmgrInfo.
+	 */
+	fcontext = AllocSetContextCreate(finfo->fn_mcxt,
+									 "SQL function",
+									 ALLOCSET_DEFAULT_SIZES);
+
+	oldcontext = MemoryContextSwitchTo(fcontext);
+
+	/*
+	 * Create the struct proper, link it to fcontext and fn_extra.  Once this
+	 * is done, we'll be able to recover the memory after failure, even if the
+	 * FmgrInfo is long-lived.
+	 */
+	fcache = (SQLFunctionCachePtr) palloc0(sizeof(SQLFunctionCache));
+	fcache->fcontext = fcontext;
+	finfo->fn_extra = (void *) fcache;
+
+	/*
+	 * get the procedure tuple corresponding to the given function Oid
+	 */
+	procedureTuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(foid));
+	if (!HeapTupleIsValid(procedureTuple))
+		elog(ERROR, "cache lookup failed for function %u", foid);
+	procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
+
+	/*
+	 * copy function name immediately for use by error reporting callback, and
+	 * for use as memory context identifier
+	 */
+	fcache->fname = pstrdup(NameStr(procedureStruct->proname));
+	MemoryContextSetIdentifier(fcontext, fcache->fname);
+
+	/*
+	 * Resolve any polymorphism, obtaining the actual result type, and the
+	 * corresponding tupdesc if it's a rowtype.
+	 */
+	(void) get_call_result_type(fcinfo, &rettype, &rettupdesc);
+
+	fcache->rettype = rettype;
+
+	/* Fetch the typlen and byval info for the result type */
+	get_typlenbyval(rettype, &fcache->typlen, &fcache->typbyval);
+
+	/* Remember whether we're returning setof something */
+	fcache->returnsSet = procedureStruct->proretset;
+
+	/* Remember if function is STABLE/IMMUTABLE */
+	fcache->readonly_func =
+		(procedureStruct->provolatile != PROVOLATILE_VOLATILE);
+
+	/*
+	 * We need the actual argument types to pass to the parser.  Also make
+	 * sure that parameter symbols are considered to have the function's
+	 * resolved input collation.
+	 */
+	fcache->pinfo = prepare_sql_fn_parse_info(procedureTuple,
+											  finfo->fn_expr,
+											  collation);
+
+	/*
+	 * And of course we need the function body text.
+	 */
+	tmp = SysCacheGetAttr(PROCOID,
+						  procedureTuple,
+						  Anum_pg_proc_prosrc,
+						  &isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", foid);
+	fcache->src = TextDatumGetCString(tmp);
+
+	/* If we have prosqlbody, pay attention to that not prosrc. */
+	tmp = SysCacheGetAttr(PROCOID,
+						  procedureTuple,
+						  Anum_pg_proc_prosqlbody,
+						  &isNull);
+
+	/*
+	 * Parse and rewrite the queries in the function text.  Use sublists to
+	 * keep track of the original query boundaries.
+	 *
+	 * Note: since parsing and planning is done in fcontext, we will generate
+	 * a lot of cruft that lives as long as the fcache does.  This is annoying
+	 * but we'll not worry about it until the module is rewritten to use
+	 * plancache.c.
+	 */
+	queryTree_list = NIL;
+	if (!isNull)
+	{
+		Node	   *n;
+		List	   *stored_query_list;
+
+		n = stringToNode(TextDatumGetCString(tmp));
+		if (IsA(n, List))
+			stored_query_list = linitial_node(List, castNode(List, n));
+		else
+			stored_query_list = list_make1(n);
+
+		foreach(lc, stored_query_list)
+		{
+			Query	   *parsetree = lfirst_node(Query, lc);
+			List	   *queryTree_sublist;
+
+			AcquireRewriteLocks(parsetree, true, false);
+			queryTree_sublist = pg_rewrite_query(parsetree);
+			queryTree_list = lappend(queryTree_list, queryTree_sublist);
+		}
+	}
+	else
+	{
+		List	   *raw_parsetree_list;
+
+		raw_parsetree_list = pg_parse_query(fcache->src);
+
+		foreach(lc, raw_parsetree_list)
+		{
+			RawStmt    *parsetree = lfirst_node(RawStmt, lc);
+			List	   *queryTree_sublist;
+
+			queryTree_sublist = pg_analyze_and_rewrite_params(parsetree,
+															  fcache->src,
+															  (ParserSetupHook) sql_fn_parser_setup,
+															  fcache->pinfo,
+															  NULL);
+			queryTree_list = lappend(queryTree_list, queryTree_sublist);
+		}
+	}
+
+	/*
+	 * Check that there are no statements we don't want to allow.
+	 */
+	check_sql_fn_statements(queryTree_list);
+
+	/*
+	 * Check that the function returns the type it claims to.  Although in
+	 * simple cases this was already done when the function was defined, we
+	 * have to recheck because database objects used in the function's queries
+	 * might have changed type.  We'd have to recheck anyway if the function
+	 * had any polymorphic arguments.  Moreover, check_sql_fn_retval takes
+	 * care of injecting any required column type coercions.  (But we don't
+	 * ask it to insert nulls for dropped columns; the junkfilter handles
+	 * that.)
+	 *
+	 * Note: we set fcache->returnsTuple according to whether we are returning
+	 * the whole tuple result or just a single column.  In the latter case we
+	 * clear returnsTuple because we need not act different from the scalar
+	 * result case, even if it's a rowtype column.  (However, we have to force
+	 * lazy eval mode in that case; otherwise we'd need extra code to expand
+	 * the rowtype column into multiple columns, since we have no way to
+	 * notify the caller that it should do that.)
+	 */
+	fcache->returnsTuple = check_sql_fn_retval(queryTree_list,
+											   rettype,
+											   rettupdesc,
+											   false,
+											   &resulttlist);
+
+	/*
+	 * Construct a JunkFilter we can use to coerce the returned rowtype to the
+	 * desired form, unless the result type is VOID, in which case there's
+	 * nothing to coerce to.  (XXX Frequently, the JunkFilter isn't doing
+	 * anything very interesting, but much of this module expects it to be
+	 * there anyway.)
+	 */
+	if (rettype != VOIDOID)
+	{
+		TupleTableSlot *slot = MakeSingleTupleTableSlot(NULL,
+														&TTSOpsMinimalTuple);
+
+		/*
+		 * If the result is composite, *and* we are returning the whole tuple
+		 * result, we need to insert nulls for any dropped columns.  In the
+		 * single-column-result case, there might be dropped columns within
+		 * the composite column value, but it's not our problem here.  There
+		 * should be no resjunk entries in resulttlist, so in the second case
+		 * the JunkFilter is certainly a no-op.
+		 */
+		if (rettupdesc && fcache->returnsTuple)
+			fcache->junkFilter = ExecInitJunkFilterConversion(resulttlist,
+															  rettupdesc,
+															  slot);
+		else
+			fcache->junkFilter = ExecInitJunkFilter(resulttlist, slot);
+	}
+
+	if (fcache->returnsTuple)
+	{
+		/* Make sure output rowtype is properly blessed */
+		BlessTupleDesc(fcache->junkFilter->jf_resultSlot->tts_tupleDescriptor);
+	}
+	else if (fcache->returnsSet && type_is_rowtype(fcache->rettype))
+	{
+		/*
+		 * Returning rowtype as if it were scalar --- materialize won't work.
+		 * Right now it's sufficient to override any caller preference for
+		 * materialize mode, but to add more smarts in init_execution_state
+		 * about this, we'd probably need a three-way flag instead of bool.
+		 */
+		lazyEvalOK = true;
+	}
+
+	/* Finally, plan the queries */
+	fcache->func_state = init_execution_state(queryTree_list,
+											  fcache,
+											  lazyEvalOK);
+
+	/* Mark fcache with time of creation to show it's valid */
+	fcache->lxid = MyProc->lxid;
+	fcache->subxid = GetCurrentSubTransactionId();
+
+	ReleaseSysCache(procedureTuple);
+
+	MemoryContextSwitchTo(oldcontext);
+}
+
+/* Start up execution of one execution_state node */
+static void
+postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
+{
+	DestReceiver *dest;
+
+	Assert(es->qd == NULL);
+
+	/* Caller should have ensured a suitable snapshot is active */
+	Assert(ActiveSnapshotSet());
+
+	/*
+	 * If this query produces the function result, send its output to the
+	 * tuplestore; else discard any output.
+	 */
+	if (es->setsResult)
+	{
+		DR_sqlfunction *myState;
+
+		dest = CreateDestReceiver(DestSQLFunction);
+		/* pass down the needed info to the dest receiver routines */
+		myState = (DR_sqlfunction *) dest;
+		Assert(myState->pub.mydest == DestSQLFunction);
+		myState->tstore = fcache->tstore;
+		myState->cxt = CurrentMemoryContext;
+		myState->filter = fcache->junkFilter;
+	}
+	else
+		dest = None_Receiver;
+
+	es->qd = CreateQueryDesc(es->stmt,
+							 fcache->src,
+							 GetActiveSnapshot(),
+							 InvalidSnapshot,
+							 dest,
+							 fcache->paramLI,
+							 es->qd ? es->qd->queryEnv : NULL,
+							 0);
+
+	/* Utility commands don't need Executor. */
+	if (es->qd->operation != CMD_UTILITY)
+	{
+		/*
+		 * In lazyEval mode, do not let the executor set up an AfterTrigger
+		 * context.  This is necessary not just an optimization, because we
+		 * mustn't exit from the function execution with a stacked
+		 * AfterTrigger level still active.  We are careful not to select
+		 * lazyEval mode for any statement that could possibly queue triggers.
+		 */
+		int			eflags;
+
+		if (es->lazyEval)
+			eflags = EXEC_FLAG_SKIP_TRIGGERS;
+		else
+			eflags = 0;			/* default run-to-completion flags */
+		ExecutorStart(es->qd, eflags);
+	}
+
+	es->status = F_EXEC_RUN;
+}
+
+/* Run one execution_state; either to completion or to first result row */
+/* Returns true if we ran to completion */
+static bool
+postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
+{
+	bool		result;
+
+	if (es->qd->operation == CMD_UTILITY)
+	{
+		ProcessUtility(es->qd->plannedstmt,
+					   fcache->src,
+					   false,
+					   PROCESS_UTILITY_QUERY,
+					   es->qd->params,
+					   es->qd->queryEnv,
+					   es->qd->dest,
+					   NULL);
+		result = true;			/* never stops early */
+	}
+	else
+	{
+		/* Run regular commands to completion unless lazyEval */
+		uint64		count = (es->lazyEval) ? 1 : 0;
+
+		ExecutorRun(es->qd, ForwardScanDirection, count, !fcache->returnsSet || !es->lazyEval);
+
+		/*
+		 * If we requested run to completion OR there was no tuple returned,
+		 * command must be complete.
+		 */
+		result = (count == 0 || es->qd->estate->es_processed == 0);
+	}
+
+	return result;
+}
+
+/* Shut down execution of one execution_state node */
+static void
+postquel_end(execution_state *es)
+{
+	/* mark status done to ensure we don't do ExecutorEnd twice */
+	es->status = F_EXEC_DONE;
+
+	/* Utility commands don't need Executor. */
+	if (es->qd->operation != CMD_UTILITY)
+	{
+		ExecutorFinish(es->qd);
+		ExecutorEnd(es->qd);
+	}
+
+	es->qd->dest->rDestroy(es->qd->dest);
+
+	FreeQueryDesc(es->qd);
+	es->qd = NULL;
+}
+
+/* Build ParamListInfo array representing current arguments */
+static void
+postquel_sub_params(SQLFunctionCachePtr fcache,
+					FunctionCallInfo fcinfo)
+{
+	int			nargs = fcinfo->nargs;
+
+	if (nargs > 0)
+	{
+		ParamListInfo paramLI;
+
+		if (fcache->paramLI == NULL)
+		{
+			paramLI = makeParamList(nargs);
+			fcache->paramLI = paramLI;
+		}
+		else
+		{
+			paramLI = fcache->paramLI;
+			Assert(paramLI->numParams == nargs);
+		}
+
+		for (int i = 0; i < nargs; i++)
+		{
+			ParamExternData *prm = &paramLI->params[i];
+
+			prm->value = fcinfo->args[i].value;
+			prm->isnull = fcinfo->args[i].isnull;
+			prm->pflags = 0;
+			prm->ptype = fcache->pinfo->argtypes[i];
+		}
+	}
+	else
+		fcache->paramLI = NULL;
+}
+
+/*
+ * Extract the SQL function's value from a single result row.  This is used
+ * both for scalar (non-set) functions and for each row of a lazy-eval set
+ * result.
+ */
+static Datum
+postquel_get_single_result(TupleTableSlot *slot,
+						   FunctionCallInfo fcinfo,
+						   SQLFunctionCachePtr fcache,
+						   MemoryContext resultcontext)
+{
+	Datum		value;
+	MemoryContext oldcontext;
+
+	/*
+	 * Set up to return the function value.  For pass-by-reference datatypes,
+	 * be sure to allocate the result in resultcontext, not the current memory
+	 * context (which has query lifespan).  We can't leave the data in the
+	 * TupleTableSlot because we intend to clear the slot before returning.
+	 */
+	oldcontext = MemoryContextSwitchTo(resultcontext);
+
+	if (fcache->returnsTuple)
+	{
+		/* We must return the whole tuple as a Datum. */
+		fcinfo->isnull = false;
+		value = ExecFetchSlotHeapTupleDatum(slot);
+	}
+	else
+	{
+		/*
+		 * Returning a scalar, which we have to extract from the first column
+		 * of the SELECT result, and then copy into result context if needed.
+		 */
+		value = slot_getattr(slot, 1, &(fcinfo->isnull));
+
+		if (!fcinfo->isnull)
+			value = datumCopy(value, fcache->typbyval, fcache->typlen);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+
+	return value;
+}
+
+/*
+ * fmgr_sql: function call manager for SQL functions
+ */
+Datum
+fmgr_sql(PG_FUNCTION_ARGS)
+{
+	SQLFunctionCachePtr fcache;
+	ErrorContextCallback sqlerrcontext;
+	MemoryContext oldcontext;
+	bool		randomAccess;
+	bool		lazyEvalOK;
+	bool		is_first;
+	bool		pushed_snapshot;
+	execution_state *es;
+	TupleTableSlot *slot;
+	Datum		result;
+	List	   *eslist;
+	ListCell   *eslc;
+
+	/*
+	 * Setup error traceback support for ereport()
+	 */
+	sqlerrcontext.callback = sql_exec_error_callback;
+	sqlerrcontext.arg = fcinfo->flinfo;
+	sqlerrcontext.previous = error_context_stack;
+	error_context_stack = &sqlerrcontext;
+
+	/* Check call context */
+	if (fcinfo->flinfo->fn_retset)
+	{
+		ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
+
+		/*
+		 * For simplicity, we require callers to support both set eval modes.
+		 * There are cases where we must use one or must use the other, and
+		 * it's not really worthwhile to postpone the check till we know. But
+		 * note we do not require caller to provide an expectedDesc.
+		 */
+		if (!rsi || !IsA(rsi, ReturnSetInfo) ||
+			(rsi->allowedModes & SFRM_ValuePerCall) == 0 ||
+			(rsi->allowedModes & SFRM_Materialize) == 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("set-valued function called in context that cannot accept a set")));
+		randomAccess = rsi->allowedModes & SFRM_Materialize_Random;
+		lazyEvalOK = !(rsi->allowedModes & SFRM_Materialize_Preferred);
+	}
+	else
+	{
+		randomAccess = false;
+		lazyEvalOK = true;
+	}
+
+	/*
+	 * Initialize fcache (build plans) if first time through; or re-initialize
+	 * if the cache is stale.
+	 */
+	fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
+
+	if (fcache != NULL)
+	{
+		if (fcache->lxid != MyProc->lxid ||
+			!SubTransactionIsActive(fcache->subxid))
+		{
+			/* It's stale; unlink and delete */
+			fcinfo->flinfo->fn_extra = NULL;
+			MemoryContextDelete(fcache->fcontext);
+			fcache = NULL;
+		}
+	}
+
+	if (fcache == NULL)
+	{
+		init_sql_fcache(fcinfo, PG_GET_COLLATION(), lazyEvalOK);
+		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
+	}
+
+	/*
+	 * Switch to context in which the fcache lives.  This ensures that our
+	 * tuplestore etc will have sufficient lifetime.  The sub-executor is
+	 * responsible for deleting per-tuple information.  (XXX in the case of a
+	 * long-lived FmgrInfo, this policy represents more memory leakage, but
+	 * it's not entirely clear where to keep stuff instead.)
+	 */
+	oldcontext = MemoryContextSwitchTo(fcache->fcontext);
+
+	/*
+	 * Find first unfinished query in function, and note whether it's the
+	 * first query.
+	 */
+	eslist = fcache->func_state;
+	es = NULL;
+	is_first = true;
+	foreach(eslc, eslist)
+	{
+		es = (execution_state *) lfirst(eslc);
+
+		while (es && es->status == F_EXEC_DONE)
+		{
+			is_first = false;
+			es = es->next;
+		}
+
+		if (es)
+			break;
+	}
+
+	/*
+	 * Convert params to appropriate format if starting a fresh execution. (If
+	 * continuing execution, we can re-use prior params.)
+	 */
+	if (is_first && es && es->status == F_EXEC_START)
+		postquel_sub_params(fcache, fcinfo);
+
+	/*
+	 * Build tuplestore to hold results, if we don't have one already. Note
+	 * it's in the query-lifespan context.
+	 */
+	if (!fcache->tstore)
+		fcache->tstore = tuplestore_begin_heap(randomAccess, false, work_mem);
+
+	/*
+	 * Execute each command in the function one after another until we either
+	 * run out of commands or get a result row from a lazily-evaluated SELECT.
+	 *
+	 * Notes about snapshot management:
+	 *
+	 * In a read-only function, we just use the surrounding query's snapshot.
+	 *
+	 * In a non-read-only function, we rely on the fact that we'll never
+	 * suspend execution between queries of the function: the only reason to
+	 * suspend execution before completion is if we are returning a row from a
+	 * lazily-evaluated SELECT.  So, when first entering this loop, we'll
+	 * either start a new query (and push a fresh snapshot) or re-establish
+	 * the active snapshot from the existing query descriptor.  If we need to
+	 * start a new query in a subsequent execution of the loop, either we need
+	 * a fresh snapshot (and pushed_snapshot is false) or the existing
+	 * snapshot is on the active stack and we can just bump its command ID.
+	 */
+	pushed_snapshot = false;
+	while (es)
+	{
+		bool		completed;
+
+		if (es->status == F_EXEC_START)
+		{
+			/*
+			 * If not read-only, be sure to advance the command counter for
+			 * each command, so that all work to date in this transaction is
+			 * visible.  Take a new snapshot if we don't have one yet,
+			 * otherwise just bump the command ID in the existing snapshot.
+			 */
+			if (!fcache->readonly_func)
+			{
+				CommandCounterIncrement();
+				if (!pushed_snapshot)
+				{
+					PushActiveSnapshot(GetTransactionSnapshot());
+					pushed_snapshot = true;
+				}
+				else
+					UpdateActiveSnapshotCommandId();
+			}
+
+			postquel_start(es, fcache);
+		}
+		else if (!fcache->readonly_func && !pushed_snapshot)
+		{
+			/* Re-establish active snapshot when re-entering function */
+			PushActiveSnapshot(es->qd->snapshot);
+			pushed_snapshot = true;
+		}
+
+		completed = postquel_getnext(es, fcache);
+
+		/*
+		 * If we ran the command to completion, we can shut it down now. Any
+		 * row(s) we need to return are safely stashed in the tuplestore, and
+		 * we want to be sure that, for example, AFTER triggers get fired
+		 * before we return anything.  Also, if the function doesn't return
+		 * set, we can shut it down anyway because it must be a SELECT and we
+		 * don't care about fetching any more result rows.
+		 */
+		if (completed || !fcache->returnsSet)
+			postquel_end(es);
+
+		/*
+		 * Break from loop if we didn't shut down (implying we got a
+		 * lazily-evaluated row).  Otherwise we'll press on till the whole
+		 * function is done, relying on the tuplestore to keep hold of the
+		 * data to eventually be returned.  This is necessary since an
+		 * INSERT/UPDATE/DELETE RETURNING that sets the result might be
+		 * followed by additional rule-inserted commands, and we want to
+		 * finish doing all those commands before we return anything.
+		 */
+		if (es->status != F_EXEC_DONE)
+			break;
+
+		/*
+		 * Advance to next execution_state, which might be in the next list.
+		 */
+		es = es->next;
+		while (!es)
+		{
+			eslc = lnext(eslist, eslc);
+			if (!eslc)
+				break;			/* end of function */
+
+			es = (execution_state *) lfirst(eslc);
+
+			/*
+			 * Flush the current snapshot so that we will take a new one for
+			 * the new query list.  This ensures that new snaps are taken at
+			 * original-query boundaries, matching the behavior of interactive
+			 * execution.
+			 */
+			if (pushed_snapshot)
+			{
+				PopActiveSnapshot();
+				pushed_snapshot = false;
+			}
+		}
+	}
+
+	/*
+	 * The tuplestore now contains whatever row(s) we are supposed to return.
+	 */
+	if (fcache->returnsSet)
+	{
+		ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
+
+		if (es)
+		{
+			/*
+			 * If we stopped short of being done, we must have a lazy-eval
+			 * row.
+			 */
+			Assert(es->lazyEval);
+			/* Re-use the junkfilter's output slot to fetch back the tuple */
+			Assert(fcache->junkFilter);
+			slot = fcache->junkFilter->jf_resultSlot;
+			if (!tuplestore_gettupleslot(fcache->tstore, true, false, slot))
+				elog(ERROR, "failed to fetch lazy-eval tuple");
+			/* Extract the result as a datum, and copy out from the slot */
+			result = postquel_get_single_result(slot, fcinfo,
+												fcache, oldcontext);
+			/* Clear the tuplestore, but keep it for next time */
+			/* NB: this might delete the slot's content, but we don't care */
+			tuplestore_clear(fcache->tstore);
+
+			/*
+			 * Let caller know we're not finished.
+			 */
+			rsi->isDone = ExprMultipleResult;
+
+			/*
+			 * Ensure we will get shut down cleanly if the exprcontext is not
+			 * run to completion.
+			 */
+			if (!fcache->shutdown_reg)
+			{
+				RegisterExprContextCallback(rsi->econtext,
+											ShutdownSQLFunction,
+											PointerGetDatum(fcache));
+				fcache->shutdown_reg = true;
+			}
+		}
+		else if (fcache->lazyEval)
+		{
+			/*
+			 * We are done with a lazy evaluation.  Clean up.
+			 */
+			tuplestore_clear(fcache->tstore);
+
+			/*
+			 * Let caller know we're finished.
+			 */
+			rsi->isDone = ExprEndResult;
+
+			fcinfo->isnull = true;
+			result = (Datum) 0;
+
+			/* Deregister shutdown callback, if we made one */
+			if (fcache->shutdown_reg)
+			{
+				UnregisterExprContextCallback(rsi->econtext,
+											  ShutdownSQLFunction,
+											  PointerGetDatum(fcache));
+				fcache->shutdown_reg = false;
+			}
+		}
+		else
+		{
+			/*
+			 * We are done with a non-lazy evaluation.  Return whatever is in
+			 * the tuplestore.  (It is now caller's responsibility to free the
+			 * tuplestore when done.)
+			 */
+			rsi->returnMode = SFRM_Materialize;
+			rsi->setResult = fcache->tstore;
+			fcache->tstore = NULL;
+			/* must copy desc because execSRF.c will free it */
+			if (fcache->junkFilter)
+				rsi->setDesc = CreateTupleDescCopy(fcache->junkFilter->jf_cleanTupType);
+
+			fcinfo->isnull = true;
+			result = (Datum) 0;
+
+			/* Deregister shutdown callback, if we made one */
+			if (fcache->shutdown_reg)
+			{
+				UnregisterExprContextCallback(rsi->econtext,
+											  ShutdownSQLFunction,
+											  PointerGetDatum(fcache));
+				fcache->shutdown_reg = false;
+			}
+		}
+	}
+	else
+	{
+		/*
+		 * Non-set function.  If we got a row, return it; else return NULL.
+		 */
+		if (fcache->junkFilter)
+		{
+			/* Re-use the junkfilter's output slot to fetch back the tuple */
+			slot = fcache->junkFilter->jf_resultSlot;
+			if (tuplestore_gettupleslot(fcache->tstore, true, false, slot))
+				result = postquel_get_single_result(slot, fcinfo,
+													fcache, oldcontext);
+			else
+			{
+				fcinfo->isnull = true;
+				result = (Datum) 0;
+			}
+		}
+		else
+		{
+			/* Should only get here for VOID functions and procedures */
+			Assert(fcache->rettype == VOIDOID);
+			fcinfo->isnull = true;
+			result = (Datum) 0;
+		}
+
+		/* Clear the tuplestore, but keep it for next time */
+		tuplestore_clear(fcache->tstore);
+	}
+
+	/* Pop snapshot if we have pushed one */
+	if (pushed_snapshot)
+		PopActiveSnapshot();
+
+	/*
+	 * If we've gone through every command in the function, we are done. Reset
+	 * the execution states to start over again on next call.
+	 */
+	if (es == NULL)
+	{
+		foreach(eslc, fcache->func_state)
+		{
+			es = (execution_state *) lfirst(eslc);
+			while (es)
+			{
+				es->status = F_EXEC_START;
+				es = es->next;
+			}
+		}
+	}
+
+	error_context_stack = sqlerrcontext.previous;
+
+	MemoryContextSwitchTo(oldcontext);
+
+	return result;
+}
+
+
+/*
+ * error context callback to let us supply a call-stack traceback
+ */
+static void
+sql_exec_error_callback(void *arg)
+{
+	FmgrInfo   *flinfo = (FmgrInfo *) arg;
+	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) flinfo->fn_extra;
+	int			syntaxerrposition;
+
+	/*
+	 * We can do nothing useful if init_sql_fcache() didn't get as far as
+	 * saving the function name
+	 */
+	if (fcache == NULL || fcache->fname == NULL)
+		return;
+
+	/*
+	 * If there is a syntax error position, convert to internal syntax error
+	 */
+	syntaxerrposition = geterrposition();
+	if (syntaxerrposition > 0 && fcache->src != NULL)
+	{
+		errposition(0);
+		internalerrposition(syntaxerrposition);
+		internalerrquery(fcache->src);
+	}
+
+	/*
+	 * Try to determine where in the function we failed.  If there is a query
+	 * with non-null QueryDesc, finger it.  (We check this rather than looking
+	 * for F_EXEC_RUN state, so that errors during ExecutorStart or
+	 * ExecutorEnd are blamed on the appropriate query; see postquel_start and
+	 * postquel_end.)
+	 */
+	if (fcache->func_state)
+	{
+		execution_state *es;
+		int			query_num;
+		ListCell   *lc;
+
+		es = NULL;
+		query_num = 1;
+		foreach(lc, fcache->func_state)
+		{
+			es = (execution_state *) lfirst(lc);
+			while (es)
+			{
+				if (es->qd)
+				{
+					errcontext("SQL function \"%s\" statement %d",
+							   fcache->fname, query_num);
+					break;
+				}
+				es = es->next;
+			}
+			if (es)
+				break;
+			query_num++;
+		}
+		if (es == NULL)
+		{
+			/*
+			 * couldn't identify a running query; might be function entry,
+			 * function exit, or between queries.
+			 */
+			errcontext("SQL function \"%s\"", fcache->fname);
+		}
+	}
+	else
+	{
+		/*
+		 * Assume we failed during init_sql_fcache().  (It's possible that the
+		 * function actually has an empty body, but in that case we may as
+		 * well report all errors as being "during startup".)
+		 */
+		errcontext("SQL function \"%s\" during startup", fcache->fname);
+	}
+}
+
+
+/*
+ * callback function in case a function-returning-set needs to be shut down
+ * before it has been run to completion
+ */
+static void
+ShutdownSQLFunction(Datum arg)
+{
+	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
+	execution_state *es;
+	ListCell   *lc;
+
+	foreach(lc, fcache->func_state)
+	{
+		es = (execution_state *) lfirst(lc);
+		while (es)
+		{
+			/* Shut down anything still running */
+			if (es->status == F_EXEC_RUN)
+			{
+				/* Re-establish active snapshot for any called functions */
+				if (!fcache->readonly_func)
+					PushActiveSnapshot(es->qd->snapshot);
+
+				postquel_end(es);
+
+				if (!fcache->readonly_func)
+					PopActiveSnapshot();
+			}
+
+			/* Reset states to START in case we're called again */
+			es->status = F_EXEC_START;
+			es = es->next;
+		}
+	}
+
+	/* Release tuplestore if we have one */
+	if (fcache->tstore)
+		tuplestore_end(fcache->tstore);
+	fcache->tstore = NULL;
+
+	/* execUtils will deregister the callback... */
+	fcache->shutdown_reg = false;
+}
+
+/*
+ * check_sql_fn_statements
+ *
+ * Check statements in an SQL function.  Error out if there is anything that
+ * is not acceptable.
+ */
+void
+check_sql_fn_statements(List *queryTreeLists)
+{
+	ListCell   *lc;
+
+	/* We are given a list of sublists of Queries */
+	foreach(lc, queryTreeLists)
+	{
+		List	   *sublist = lfirst_node(List, lc);
+		ListCell   *lc2;
+
+		foreach(lc2, sublist)
+		{
+			Query	   *query = lfirst_node(Query, lc2);
+
+			/*
+			 * Disallow calling procedures with output arguments.  The current
+			 * implementation would just throw the output values away, unless
+			 * the statement is the last one.  Per SQL standard, we should
+			 * assign the output values by name.  By disallowing this here, we
+			 * preserve an opportunity for future improvement.
+			 */
+			if (query->commandType == CMD_UTILITY &&
+				IsA(query->utilityStmt, CallStmt))
+			{
+				CallStmt   *stmt = (CallStmt *) query->utilityStmt;
+
+				if (stmt->outargs != NIL)
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("calling procedures with output arguments is not supported in SQL functions")));
+			}
+		}
+	}
+}
+
+/*
+ * check_sql_fn_retval()
+ *		Check return value of a list of lists of sql parse trees.
+ *
+ * The return value of a sql function is the value returned by the last
+ * canSetTag query in the function.  We do some ad-hoc type checking and
+ * coercion here to ensure that the function returns what it's supposed to.
+ * Note that we may actually modify the last query to make it match!
+ *
+ * This function returns true if the sql function returns the entire tuple
+ * result of its final statement, or false if it returns just the first column
+ * result of that statement.  It throws an error if the final statement doesn't
+ * return the right type at all.
+ *
+ * Note that because we allow "SELECT rowtype_expression", the result can be
+ * false even when the declared function return type is a rowtype.
+ *
+ * For a polymorphic function the passed rettype must be the actual resolved
+ * output type of the function.  (This means we can't check the type during
+ * function definition of a polymorphic function.)  If we do see a polymorphic
+ * rettype we'll throw an error, saying it is not a supported rettype.
+ *
+ * If the function returns composite, the passed rettupdesc should describe
+ * the expected output.  If rettupdesc is NULL, we can't verify that the
+ * output matches; that should only happen in fmgr_sql_validator(), or when
+ * the function returns RECORD and the caller doesn't actually care which
+ * composite type it is.
+ *
+ * (Typically, rettype and rettupdesc are computed by get_call_result_type
+ * or a sibling function.)
+ *
+ * In addition to coercing individual output columns, we can modify the
+ * output to include dummy NULL columns for any dropped columns appearing
+ * in rettupdesc.  This is done only if the caller asks for it.
+ *
+ * If resultTargetList isn't NULL, then *resultTargetList is set to the
+ * targetlist that defines the final statement's result.  Exception: if the
+ * function is defined to return VOID then *resultTargetList is set to NIL.
+ */
+bool
+check_sql_fn_retval(List *queryTreeLists,
+					Oid rettype, TupleDesc rettupdesc,
+					bool insertDroppedCols,
+					List **resultTargetList)
+{
+	bool		is_tuple_result = false;
+	Query	   *parse;
+	ListCell   *parse_cell;
+	List	   *tlist;
+	int			tlistlen;
+	bool		tlist_is_modifiable;
+	char		fn_typtype;
+	List	   *upper_tlist = NIL;
+	bool		upper_tlist_nontrivial = false;
+	ListCell   *lc;
+
+	if (resultTargetList)
+		*resultTargetList = NIL;	/* initialize in case of VOID result */
+
+	/*
+	 * If it's declared to return VOID, we don't care what's in the function.
+	 * (This takes care of the procedure case, as well.)
+	 */
+	if (rettype == VOIDOID)
+		return false;
+
+	/*
+	 * Find the last canSetTag query in the function body (which is presented
+	 * to us as a list of sublists of Query nodes).  This isn't necessarily
+	 * the last parsetree, because rule rewriting can insert queries after
+	 * what the user wrote.  Note that it might not even be in the last
+	 * sublist, for example if the last query rewrites to DO INSTEAD NOTHING.
+	 * (It might not be unreasonable to throw an error in such a case, but
+	 * this is the historical behavior and it doesn't seem worth changing.)
+	 */
+	parse = NULL;
+	parse_cell = NULL;
+	foreach(lc, queryTreeLists)
+	{
+		List	   *sublist = lfirst_node(List, lc);
+		ListCell   *lc2;
+
+		foreach(lc2, sublist)
+		{
+			Query	   *q = lfirst_node(Query, lc2);
+
+			if (q->canSetTag)
+			{
+				parse = q;
+				parse_cell = lc2;
+			}
+		}
+	}
+
+	/*
+	 * If it's a plain SELECT, it returns whatever the targetlist says.
+	 * Otherwise, if it's INSERT/UPDATE/DELETE with RETURNING, it returns
+	 * that. Otherwise, the function return type must be VOID.
+	 *
+	 * Note: eventually replace this test with QueryReturnsTuples?	We'd need
+	 * a more general method of determining the output type, though.  Also, it
+	 * seems too dangerous to consider FETCH or EXECUTE as returning a
+	 * determinable rowtype, since they depend on relatively short-lived
+	 * entities.
+	 */
+	if (parse &&
+		parse->commandType == CMD_SELECT)
+	{
+		tlist = parse->targetList;
+		/* tlist is modifiable unless it's a dummy in a setop query */
+		tlist_is_modifiable = (parse->setOperations == NULL);
+	}
+	else if (parse &&
+			 (parse->commandType == CMD_INSERT ||
+			  parse->commandType == CMD_UPDATE ||
+			  parse->commandType == CMD_DELETE) &&
+			 parse->returningList)
+	{
+		tlist = parse->returningList;
+		/* returningList can always be modified */
+		tlist_is_modifiable = true;
+	}
+	else
+	{
+		/* Empty function body, or last statement is a utility command */
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("return type mismatch in function declared to return %s",
+						format_type_be(rettype)),
+				 errdetail("Function's final statement must be SELECT or INSERT/UPDATE/DELETE RETURNING.")));
+		return false;			/* keep compiler quiet */
+	}
+
+	/*
+	 * OK, check that the targetlist returns something matching the declared
+	 * type, and modify it if necessary.  If possible, we insert any coercion
+	 * steps right into the final statement's targetlist.  However, that might
+	 * risk changes in the statement's semantics --- we can't safely change
+	 * the output type of a grouping column, for instance.  In such cases we
+	 * handle coercions by inserting an extra level of Query that effectively
+	 * just does a projection.
+	 */
+
+	/*
+	 * Count the non-junk entries in the result targetlist.
+	 */
+	tlistlen = ExecCleanTargetListLength(tlist);
+
+	fn_typtype = get_typtype(rettype);
+
+	if (fn_typtype == TYPTYPE_BASE ||
+		fn_typtype == TYPTYPE_DOMAIN ||
+		fn_typtype == TYPTYPE_ENUM ||
+		fn_typtype == TYPTYPE_RANGE ||
+		fn_typtype == TYPTYPE_MULTIRANGE)
+	{
+		/*
+		 * For scalar-type returns, the target list must have exactly one
+		 * non-junk entry, and its type must be coercible to rettype.
+		 */
+		TargetEntry *tle;
+
+		if (tlistlen != 1)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("return type mismatch in function declared to return %s",
+							format_type_be(rettype)),
+					 errdetail("Final statement must return exactly one column.")));
+
+		/* We assume here that non-junk TLEs must come first in tlists */
+		tle = (TargetEntry *) linitial(tlist);
+		Assert(!tle->resjunk);
+
+		if (!coerce_fn_result_column(tle, rettype, -1,
+									 tlist_is_modifiable,
+									 &upper_tlist,
+									 &upper_tlist_nontrivial))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+					 errmsg("return type mismatch in function declared to return %s",
+							format_type_be(rettype)),
+					 errdetail("Actual return type is %s.",
+							   format_type_be(exprType((Node *) tle->expr)))));
+	}
+	else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
+	{
+		/*
+		 * Returns a rowtype.
+		 *
+		 * Note that we will not consider a domain over composite to be a
+		 * "rowtype" return type; it goes through the scalar case above.  This
+		 * is because we only provide column-by-column implicit casting, and
+		 * will not cast the complete record result.  So the only way to
+		 * produce a domain-over-composite result is to compute it as an
+		 * explicit single-column result.  The single-composite-column code
+		 * path just below could handle such cases, but it won't be reached.
+		 */
+		int			tupnatts;	/* physical number of columns in tuple */
+		int			tuplogcols; /* # of nondeleted columns in tuple */
+		int			colindex;	/* physical column index */
+
+		/*
+		 * If the target list has one non-junk entry, and that expression has
+		 * or can be coerced to the declared return type, take it as the
+		 * result.  This allows, for example, 'SELECT func2()', where func2
+		 * has the same composite return type as the function that's calling
+		 * it.  This provision creates some ambiguity --- maybe the expression
+		 * was meant to be the lone field of the composite result --- but it
+		 * works well enough as long as we don't get too enthusiastic about
+		 * inventing coercions from scalar to composite types.
+		 *
+		 * XXX Note that if rettype is RECORD and the expression is of a named
+		 * composite type, or vice versa, this coercion will succeed, whether
+		 * or not the record type really matches.  For the moment we rely on
+		 * runtime type checking to catch any discrepancy, but it'd be nice to
+		 * do better at parse time.
+		 */
+		if (tlistlen == 1)
+		{
+			TargetEntry *tle = (TargetEntry *) linitial(tlist);
+
+			Assert(!tle->resjunk);
+			if (coerce_fn_result_column(tle, rettype, -1,
+										tlist_is_modifiable,
+										&upper_tlist,
+										&upper_tlist_nontrivial))
+			{
+				/* Note that we're NOT setting is_tuple_result */
+				goto tlist_coercion_finished;
+			}
+		}
+
+		/*
+		 * If the caller didn't provide an expected tupdesc, we can't do any
+		 * further checking.  Assume we're returning the whole tuple.
+		 */
+		if (rettupdesc == NULL)
+		{
+			/* Return tlist if requested */
+			if (resultTargetList)
+				*resultTargetList = tlist;
+			return true;
+		}
+
+		/*
+		 * Verify that the targetlist matches the return tuple type.  We scan
+		 * the non-resjunk columns, and coerce them if necessary to match the
+		 * datatypes of the non-deleted attributes.  For deleted attributes,
+		 * insert NULL result columns if the caller asked for that.
+		 */
+		tupnatts = rettupdesc->natts;
+		tuplogcols = 0;			/* we'll count nondeleted cols as we go */
+		colindex = 0;
+
+		foreach(lc, tlist)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(lc);
+			Form_pg_attribute attr;
+
+			/* resjunk columns can simply be ignored */
+			if (tle->resjunk)
+				continue;
+
+			do
+			{
+				colindex++;
+				if (colindex > tupnatts)
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+							 errmsg("return type mismatch in function declared to return %s",
+									format_type_be(rettype)),
+							 errdetail("Final statement returns too many columns.")));
+				attr = TupleDescAttr(rettupdesc, colindex - 1);
+				if (attr->attisdropped && insertDroppedCols)
+				{
+					Expr	   *null_expr;
+
+					/* The type of the null we insert isn't important */
+					null_expr = (Expr *) makeConst(INT4OID,
+												   -1,
+												   InvalidOid,
+												   sizeof(int32),
+												   (Datum) 0,
+												   true,	/* isnull */
+												   true /* byval */ );
+					upper_tlist = lappend(upper_tlist,
+										  makeTargetEntry(null_expr,
+														  list_length(upper_tlist) + 1,
+														  NULL,
+														  false));
+					upper_tlist_nontrivial = true;
+				}
+			} while (attr->attisdropped);
+			tuplogcols++;
+
+			if (!coerce_fn_result_column(tle,
+										 attr->atttypid, attr->atttypmod,
+										 tlist_is_modifiable,
+										 &upper_tlist,
+										 &upper_tlist_nontrivial))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("return type mismatch in function declared to return %s",
+								format_type_be(rettype)),
+						 errdetail("Final statement returns %s instead of %s at column %d.",
+								   format_type_be(exprType((Node *) tle->expr)),
+								   format_type_be(attr->atttypid),
+								   tuplogcols)));
+		}
+
+		/* remaining columns in rettupdesc had better all be dropped */
+		for (colindex++; colindex <= tupnatts; colindex++)
+		{
+			if (!TupleDescAttr(rettupdesc, colindex - 1)->attisdropped)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("return type mismatch in function declared to return %s",
+								format_type_be(rettype)),
+						 errdetail("Final statement returns too few columns.")));
+			if (insertDroppedCols)
+			{
+				Expr	   *null_expr;
+
+				/* The type of the null we insert isn't important */
+				null_expr = (Expr *) makeConst(INT4OID,
+											   -1,
+											   InvalidOid,
+											   sizeof(int32),
+											   (Datum) 0,
+											   true,	/* isnull */
+											   true /* byval */ );
+				upper_tlist = lappend(upper_tlist,
+									  makeTargetEntry(null_expr,
+													  list_length(upper_tlist) + 1,
+													  NULL,
+													  false));
+				upper_tlist_nontrivial = true;
+			}
+		}
+
+		/* Report that we are returning entire tuple result */
+		is_tuple_result = true;
+	}
+	else
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("return type %s is not supported for SQL functions",
+						format_type_be(rettype))));
+
+tlist_coercion_finished:
+
+	/*
+	 * If necessary, modify the final Query by injecting an extra Query level
+	 * that just performs a projection.  (It'd be dubious to do this to a
+	 * non-SELECT query, but we never have to; RETURNING lists can always be
+	 * modified in-place.)
+	 */
+	if (upper_tlist_nontrivial)
+	{
+		Query	   *newquery;
+		List	   *colnames;
+		RangeTblEntry *rte;
+		RangeTblRef *rtr;
+
+		Assert(parse->commandType == CMD_SELECT);
+
+		/* Most of the upper Query struct can be left as zeroes/nulls */
+		newquery = makeNode(Query);
+		newquery->commandType = CMD_SELECT;
+		newquery->querySource = parse->querySource;
+		newquery->canSetTag = true;
+		newquery->targetList = upper_tlist;
+
+		/* We need a moderately realistic colnames list for the subquery RTE */
+		colnames = NIL;
+		foreach(lc, parse->targetList)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(lc);
+
+			if (tle->resjunk)
+				continue;
+			colnames = lappend(colnames,
+							   makeString(tle->resname ? tle->resname : ""));
+		}
+
+		/* Build a suitable RTE for the subquery */
+		rte = makeNode(RangeTblEntry);
+		rte->rtekind = RTE_SUBQUERY;
+		rte->subquery = parse;
+		rte->eref = rte->alias = makeAlias("*SELECT*", colnames);
+		rte->lateral = false;
+		rte->inh = false;
+		rte->inFromCl = true;
+		newquery->rtable = list_make1(rte);
+
+		rtr = makeNode(RangeTblRef);
+		rtr->rtindex = 1;
+		newquery->jointree = makeFromExpr(list_make1(rtr), NULL);
+
+		/* Replace original query in the correct element of the query list */
+		lfirst(parse_cell) = newquery;
+	}
+
+	/* Return tlist (possibly modified) if requested */
+	if (resultTargetList)
+		*resultTargetList = upper_tlist;
+
+	return is_tuple_result;
+}
+
+/*
+ * Process one function result column for check_sql_fn_retval
+ *
+ * Coerce the output value to the required type/typmod, and add a column
+ * to *upper_tlist for it.  Set *upper_tlist_nontrivial to true if we
+ * add an upper tlist item that's not just a Var.
+ *
+ * Returns true if OK, false if could not coerce to required type
+ * (in which case, no changes have been made)
+ */
+static bool
+coerce_fn_result_column(TargetEntry *src_tle,
+						Oid res_type,
+						int32 res_typmod,
+						bool tlist_is_modifiable,
+						List **upper_tlist,
+						bool *upper_tlist_nontrivial)
+{
+	TargetEntry *new_tle;
+	Expr	   *new_tle_expr;
+	Node	   *cast_result;
+
+	/*
+	 * If the TLE has a sortgroupref marking, don't change it, as it probably
+	 * is referenced by ORDER BY, DISTINCT, etc, and changing its type would
+	 * break query semantics.  Otherwise, it's safe to modify in-place unless
+	 * the query as a whole has issues with that.
+	 */
+	if (tlist_is_modifiable && src_tle->ressortgroupref == 0)
+	{
+		/* OK to modify src_tle in place, if necessary */
+		cast_result = coerce_to_target_type(NULL,
+											(Node *) src_tle->expr,
+											exprType((Node *) src_tle->expr),
+											res_type, res_typmod,
+											COERCION_ASSIGNMENT,
+											COERCE_IMPLICIT_CAST,
+											-1);
+		if (cast_result == NULL)
+			return false;
+		assign_expr_collations(NULL, cast_result);
+		src_tle->expr = (Expr *) cast_result;
+		/* Make a Var referencing the possibly-modified TLE */
+		new_tle_expr = (Expr *) makeVarFromTargetEntry(1, src_tle);
+	}
+	else
+	{
+		/* Any casting must happen in the upper tlist */
+		Var		   *var = makeVarFromTargetEntry(1, src_tle);
+
+		cast_result = coerce_to_target_type(NULL,
+											(Node *) var,
+											var->vartype,
+											res_type, res_typmod,
+											COERCION_ASSIGNMENT,
+											COERCE_IMPLICIT_CAST,
+											-1);
+		if (cast_result == NULL)
+			return false;
+		assign_expr_collations(NULL, cast_result);
+		/* Did the coercion actually do anything? */
+		if (cast_result != (Node *) var)
+			*upper_tlist_nontrivial = true;
+		new_tle_expr = (Expr *) cast_result;
+	}
+	new_tle = makeTargetEntry(new_tle_expr,
+							  list_length(*upper_tlist) + 1,
+							  src_tle->resname, false);
+	*upper_tlist = lappend(*upper_tlist, new_tle);
+	return true;
+}
+
+
+/*
+ * CreateSQLFunctionDestReceiver -- create a suitable DestReceiver object
+ */
+DestReceiver *
+CreateSQLFunctionDestReceiver(void)
+{
+	DR_sqlfunction *self = (DR_sqlfunction *) palloc0(sizeof(DR_sqlfunction));
+
+	self->pub.receiveSlot = sqlfunction_receive;
+	self->pub.rStartup = sqlfunction_startup;
+	self->pub.rShutdown = sqlfunction_shutdown;
+	self->pub.rDestroy = sqlfunction_destroy;
+	self->pub.mydest = DestSQLFunction;
+
+	/* private fields will be set by postquel_start */
+
+	return (DestReceiver *) self;
+}
+
+/*
+ * sqlfunction_startup --- executor startup
+ */
+static void
+sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
+{
+	/* no-op */
+}
+
+/*
+ * sqlfunction_receive --- receive one tuple
+ */
+static bool
+sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self)
+{
+	DR_sqlfunction *myState = (DR_sqlfunction *) self;
+
+	/* Filter tuple as needed */
+	slot = ExecFilterJunk(myState->filter, slot);
+
+	/* Store the filtered tuple into the tuplestore */
+	tuplestore_puttupleslot(myState->tstore, slot);
+
+	return true;
+}
+
+/*
+ * sqlfunction_shutdown --- executor end
+ */
+static void
+sqlfunction_shutdown(DestReceiver *self)
+{
+	/* no-op */
+}
+
+/*
+ * sqlfunction_destroy --- release DestReceiver object
+ */
+static void
+sqlfunction_destroy(DestReceiver *self)
+{
+	pfree(self);
+}