SQL procedures

This adds a new object type "procedure" that is similar to a function
but does not have a return type and is invoked by the new CALL statement
instead of SELECT or similar.  This implementation is aligned with the
SQL standard and compatible with or similar to other SQL implementations.

This commit adds new commands CALL, CREATE/ALTER/DROP PROCEDURE, as well
as ALTER/DROP ROUTINE that can refer to either a function or a
procedure (or an aggregate function, as an extension to SQL).  There is
also support for procedures in various utility commands such as COMMENT
and GRANT, as well as support in pg_dump and psql.  Support for defining
procedures is available in all the languages supplied by the core
distribution.

While this commit is mainly syntax sugar around existing functionality,
future features will rely on having procedures as a separate object
type.

Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

1 files changed, 153 insertions, 11 deletions

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 7de844b2cad..2a9c90133d1 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -51,6 +51,8 @@
 #include "commands/alter.h"
 #include "commands/defrem.h"
 #include "commands/proclang.h"
+#include "executor/execdesc.h"
+#include "executor/executor.h"
 #include "miscadmin.h"
 #include "optimizer/var.h"
 #include "parser/parse_coerce.h"
@@ -179,7 +181,7 @@ void
 interpret_function_parameter_list(ParseState *pstate,
 								  List *parameters,
 								  Oid languageOid,
-								  bool is_aggregate,
+								  ObjectType objtype,
 								  oidvector **parameterTypes,
 								  ArrayType **allParameterTypes,
 								  ArrayType **parameterModes,
@@ -233,7 +235,7 @@ interpret_function_parameter_list(ParseState *pstate,
 							 errmsg("SQL function cannot accept shell type %s",
 									TypeNameToString(t))));
 				/* We don't allow creating aggregates on shell types either */
-				else if (is_aggregate)
+				else if (objtype == OBJECT_AGGREGATE)
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
 							 errmsg("aggregate cannot accept shell type %s",
@@ -262,16 +264,28 @@ interpret_function_parameter_list(ParseState *pstate,
 
 		if (t->setof)
 		{
-			if (is_aggregate)
+			if (objtype == OBJECT_AGGREGATE)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
 						 errmsg("aggregates cannot accept set arguments")));
+			else if (objtype == OBJECT_PROCEDURE)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("procedures cannot accept set arguments")));
 			else
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
 						 errmsg("functions cannot accept set arguments")));
 		}
 
+		if (objtype == OBJECT_PROCEDURE)
+		{
+			if (fp->mode == FUNC_PARAM_OUT || fp->mode == FUNC_PARAM_INOUT)
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 (errmsg("procedures cannot have OUT parameters"))));
+		}
+
 		/* handle input parameters */
 		if (fp->mode != FUNC_PARAM_OUT && fp->mode != FUNC_PARAM_TABLE)
 		{
@@ -451,6 +465,7 @@ interpret_function_parameter_list(ParseState *pstate,
  */
 static bool
 compute_common_attribute(ParseState *pstate,
+						 bool is_procedure,
 						 DefElem *defel,
 						 DefElem **volatility_item,
 						 DefElem **strict_item,
@@ -463,6 +478,8 @@ compute_common_attribute(ParseState *pstate,
 {
 	if (strcmp(defel->defname, "volatility") == 0)
 	{
+		if (is_procedure)
+			goto procedure_error;
 		if (*volatility_item)
 			goto duplicate_error;
 
@@ -470,6 +487,8 @@ compute_common_attribute(ParseState *pstate,
 	}
 	else if (strcmp(defel->defname, "strict") == 0)
 	{
+		if (is_procedure)
+			goto procedure_error;
 		if (*strict_item)
 			goto duplicate_error;
 
@@ -484,6 +503,8 @@ compute_common_attribute(ParseState *pstate,
 	}
 	else if (strcmp(defel->defname, "leakproof") == 0)
 	{
+		if (is_procedure)
+			goto procedure_error;
 		if (*leakproof_item)
 			goto duplicate_error;
 
@@ -495,6 +516,8 @@ compute_common_attribute(ParseState *pstate,
 	}
 	else if (strcmp(defel->defname, "cost") == 0)
 	{
+		if (is_procedure)
+			goto procedure_error;
 		if (*cost_item)
 			goto duplicate_error;
 
@@ -502,6 +525,8 @@ compute_common_attribute(ParseState *pstate,
 	}
 	else if (strcmp(defel->defname, "rows") == 0)
 	{
+		if (is_procedure)
+			goto procedure_error;
 		if (*rows_item)
 			goto duplicate_error;
 
@@ -509,6 +534,8 @@ compute_common_attribute(ParseState *pstate,
 	}
 	else if (strcmp(defel->defname, "parallel") == 0)
 	{
+		if (is_procedure)
+			goto procedure_error;
 		if (*parallel_item)
 			goto duplicate_error;
 
@@ -526,6 +553,13 @@ duplicate_error:
 			 errmsg("conflicting or redundant options"),
 			 parser_errposition(pstate, defel->location)));
 	return false;				/* keep compiler quiet */
+
+procedure_error:
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+			 errmsg("invalid attribute in procedure definition"),
+			 parser_errposition(pstate, defel->location)));
+	return false;
 }
 
 static char
@@ -603,6 +637,7 @@ update_proconfig_value(ArrayType *a, List *set_items)
  */
 static void
 compute_attributes_sql_style(ParseState *pstate,
+							 bool is_procedure,
 							 List *options,
 							 List **as,
 							 char **language,
@@ -669,9 +704,15 @@ compute_attributes_sql_style(ParseState *pstate,
 						(errcode(ERRCODE_SYNTAX_ERROR),
 						 errmsg("conflicting or redundant options"),
 						 parser_errposition(pstate, defel->location)));
+			if (is_procedure)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("invalid attribute in procedure definition"),
+						 parser_errposition(pstate, defel->location)));
 			windowfunc_item = defel;
 		}
 		else if (compute_common_attribute(pstate,
+										  is_procedure,
 										  defel,
 										  &volatility_item,
 										  &strict_item,
@@ -762,7 +803,7 @@ compute_attributes_sql_style(ParseState *pstate,
  *------------
  */
 static void
-compute_attributes_with_style(ParseState *pstate, List *parameters, bool *isStrict_p, char *volatility_p)
+compute_attributes_with_style(ParseState *pstate, bool is_procedure, List *parameters, bool *isStrict_p, char *volatility_p)
 {
 	ListCell   *pl;
 
@@ -771,10 +812,22 @@ compute_attributes_with_style(ParseState *pstate, List *parameters, bool *isStri
 		DefElem    *param = (DefElem *) lfirst(pl);
 
 		if (pg_strcasecmp(param->defname, "isstrict") == 0)
+		{
+			if (is_procedure)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("invalid attribute in procedure definition"),
+						 parser_errposition(pstate, param->location)));
 			*isStrict_p = defGetBoolean(param);
+		}
 		else if (pg_strcasecmp(param->defname, "iscachable") == 0)
 		{
 			/* obsolete spelling of isImmutable */
+			if (is_procedure)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("invalid attribute in procedure definition"),
+						 parser_errposition(pstate, param->location)));
 			if (defGetBoolean(param))
 				*volatility_p = PROVOLATILE_IMMUTABLE;
 		}
@@ -916,6 +969,7 @@ CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt)
 
 	/* override attributes from explicit list */
 	compute_attributes_sql_style(pstate,
+								 stmt->is_procedure,
 								 stmt->options,
 								 &as_clause, &language, &transformDefElem,
 								 &isWindowFunc, &volatility,
@@ -990,7 +1044,7 @@ CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt)
 	interpret_function_parameter_list(pstate,
 									  stmt->parameters,
 									  languageOid,
-									  false,	/* not an aggregate */
+									  stmt->is_procedure ? OBJECT_PROCEDURE : OBJECT_FUNCTION,
 									  &parameterTypes,
 									  &allParameterTypes,
 									  &parameterModes,
@@ -999,7 +1053,14 @@ CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt)
 									  &variadicArgType,
 									  &requiredResultType);
 
-	if (stmt->returnType)
+	if (stmt->is_procedure)
+	{
+		Assert(!stmt->returnType);
+
+		prorettype = InvalidOid;
+		returnsSet = false;
+	}
+	else if (stmt->returnType)
 	{
 		/* explicit RETURNS clause */
 		compute_return_type(stmt->returnType, languageOid,
@@ -1045,7 +1106,7 @@ CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt)
 		trftypes = NULL;
 	}
 
-	compute_attributes_with_style(pstate, stmt->withClause, &isStrict, &volatility);
+	compute_attributes_with_style(pstate, stmt->is_procedure, stmt->withClause, &isStrict, &volatility);
 
 	interpret_AS_clause(languageOid, language, funcname, as_clause,
 						&prosrc_str, &probin_str);
@@ -1168,6 +1229,7 @@ AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt)
 	HeapTuple	tup;
 	Oid			funcOid;
 	Form_pg_proc procForm;
+	bool		is_procedure;
 	Relation	rel;
 	ListCell   *l;
 	DefElem    *volatility_item = NULL;
@@ -1182,7 +1244,7 @@ AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt)
 
 	rel = heap_open(ProcedureRelationId, RowExclusiveLock);
 
-	funcOid = LookupFuncWithArgs(stmt->func, false);
+	funcOid = LookupFuncWithArgs(stmt->objtype, stmt->func, false);
 
 	tup = SearchSysCacheCopy1(PROCOID, ObjectIdGetDatum(funcOid));
 	if (!HeapTupleIsValid(tup)) /* should not happen */
@@ -1201,12 +1263,15 @@ AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt)
 				 errmsg("\"%s\" is an aggregate function",
 						NameListToString(stmt->func->objname))));
 
+	is_procedure = (procForm->prorettype == InvalidOid);
+
 	/* Examine requested actions. */
 	foreach(l, stmt->actions)
 	{
 		DefElem    *defel = (DefElem *) lfirst(l);
 
 		if (compute_common_attribute(pstate,
+									 is_procedure,
 									 defel,
 									 &volatility_item,
 									 &strict_item,
@@ -1472,7 +1537,7 @@ CreateCast(CreateCastStmt *stmt)
 	{
 		Form_pg_proc procstruct;
 
-		funcid = LookupFuncWithArgs(stmt->func, false);
+		funcid = LookupFuncWithArgs(OBJECT_FUNCTION, stmt->func, false);
 
 		tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
 		if (!HeapTupleIsValid(tuple))
@@ -1853,7 +1918,7 @@ CreateTransform(CreateTransformStmt *stmt)
 	 */
 	if (stmt->fromsql)
 	{
-		fromsqlfuncid = LookupFuncWithArgs(stmt->fromsql, false);
+		fromsqlfuncid = LookupFuncWithArgs(OBJECT_FUNCTION, stmt->fromsql, false);
 
 		if (!pg_proc_ownercheck(fromsqlfuncid, GetUserId()))
 			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC, NameListToString(stmt->fromsql->objname));
@@ -1879,7 +1944,7 @@ CreateTransform(CreateTransformStmt *stmt)
 
 	if (stmt->tosql)
 	{
-		tosqlfuncid = LookupFuncWithArgs(stmt->tosql, false);
+		tosqlfuncid = LookupFuncWithArgs(OBJECT_FUNCTION, stmt->tosql, false);
 
 		if (!pg_proc_ownercheck(tosqlfuncid, GetUserId()))
 			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_PROC, NameListToString(stmt->tosql->objname));
@@ -2168,3 +2233,80 @@ ExecuteDoStmt(DoStmt *stmt)
 	/* execute the inline handler */
 	OidFunctionCall1(laninline, PointerGetDatum(codeblock));
 }
+
+/*
+ * Execute CALL statement
+ */
+void
+ExecuteCallStmt(ParseState *pstate, CallStmt *stmt)
+{
+	List	   *targs;
+	ListCell   *lc;
+	Node	   *node;
+	FuncExpr   *fexpr;
+	int			nargs;
+	int			i;
+	AclResult   aclresult;
+	FmgrInfo	flinfo;
+	FunctionCallInfoData fcinfo;
+
+	targs = NIL;
+	foreach(lc, stmt->funccall->args)
+	{
+		targs = lappend(targs, transformExpr(pstate,
+											 (Node *) lfirst(lc),
+											 EXPR_KIND_CALL));
+	}
+
+	node = ParseFuncOrColumn(pstate,
+							 stmt->funccall->funcname,
+							 targs,
+							 pstate->p_last_srf,
+							 stmt->funccall,
+							 true,
+							 stmt->funccall->location);
+
+	fexpr = castNode(FuncExpr, node);
+
+	aclresult = pg_proc_aclcheck(fexpr->funcid, GetUserId(), ACL_EXECUTE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, ACL_KIND_PROC, get_func_name(fexpr->funcid));
+	InvokeFunctionExecuteHook(fexpr->funcid);
+
+	nargs = list_length(fexpr->args);
+
+	/* safety check; see ExecInitFunc() */
+	if (nargs > FUNC_MAX_ARGS)
+		ereport(ERROR,
+				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
+				 errmsg_plural("cannot pass more than %d argument to a procedure",
+							   "cannot pass more than %d arguments to a procedure",
+							   FUNC_MAX_ARGS,
+							   FUNC_MAX_ARGS)));
+
+	fmgr_info(fexpr->funcid, &flinfo);
+	InitFunctionCallInfoData(fcinfo, &flinfo, nargs, fexpr->inputcollid, NULL, NULL);
+
+	i = 0;
+	foreach (lc, fexpr->args)
+	{
+		EState	   *estate;
+		ExprState  *exprstate;
+		ExprContext *econtext;
+		Datum		val;
+		bool		isnull;
+
+		estate = CreateExecutorState();
+		exprstate = ExecPrepareExpr(lfirst(lc), estate);
+		econtext = CreateStandaloneExprContext();
+		val = ExecEvalExprSwitchContext(exprstate, econtext, &isnull);
+		FreeExecutorState(estate);
+
+		fcinfo.arg[i] = val;
+		fcinfo.argnull[i] = isnull;
+
+		i++;
+	}
+
+	FunctionCallInvoke(&fcinfo);
+}