The original implementation of polymorphic aggregates didn't really get the

checking of argument compatibility right; although the problem is only exposed
with multiple-input aggregates in which some arguments are polymorphic and
some are not.  Per bug #3852 from Sokolov Yura.

src/backend/catalog/pg_aggregate.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/pg_aggregate.c,v 1.89 2008/01/01 19:45:48 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/pg_aggregate.c,v 1.90 2008/01/11 18:39:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -296,7 +296,6 @@ lookup_agg_function(List *fnName,
 	FuncDetailCode fdresult;
 	AclResult	aclresult;
 	int			i;
-	bool		allPolyArgs = true;
 
 	/*
 	 * func_get_detail looks up the function in the catalogs, does
@@ -322,25 +321,15 @@ lookup_agg_function(List *fnName,
 						func_signature_string(fnName, nargs, input_types))));
 
 	/*
-	 * If the given type(s) are all polymorphic, there's nothing we can check.
-	 * Otherwise, enforce consistency, and possibly refine the result type.
+	 * If there are any polymorphic types involved, enforce consistency, and
+	 * possibly refine the result type.  It's OK if the result is still
+	 * polymorphic at this point, though.
 	 */
-	for (i = 0; i < nargs; i++)
-	{
-		if (!IsPolymorphicType(input_types[i]))
-		{
-			allPolyArgs = false;
-			break;
-		}
-	}
-
-	if (!allPolyArgs)
-	{
-		*rettype = enforce_generic_type_consistency(input_types,
-													true_oid_array,
-													nargs,
-													*rettype);
-	}
+	*rettype = enforce_generic_type_consistency(input_types,
+												true_oid_array,
+												nargs,
+												*rettype,
+												true);
 
 	/*
 	 * func_get_detail will find functions requiring run-time argument type

src/backend/executor/nodeAgg.c

@@ -61,7 +61,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeAgg.c,v 1.155 2008/01/01 19:45:49 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeAgg.c,v 1.156 2008/01/11 18:39:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1433,7 +1433,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 			aggtranstype = enforce_generic_type_consistency(inputTypes,
 															declaredArgTypes,
 															agg_nargs,
-															aggtranstype);
+															aggtranstype,
+															false);
 			pfree(declaredArgTypes);
 		}
 

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.253 2008/01/01 19:45:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.254 2008/01/11 18:39:40 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -448,7 +448,8 @@ count_agg_clauses_walker(Node *node, AggClauseCounts *counts)
 			aggtranstype = enforce_generic_type_consistency(inputTypes,
 															declaredArgTypes,
 															agg_nargs,
-															aggtranstype);
+															aggtranstype,
+															false);
 			pfree(declaredArgTypes);
 		}
 

src/backend/parser/parse_coerce.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_coerce.c,v 2.160 2008/01/01 19:45:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_coerce.c,v 2.161 2008/01/11 18:39:40 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1255,12 +1255,20 @@ check_generic_type_consistency(Oid *actual_arg_types,
  *	  we add the extra condition that the ANYELEMENT type must not be an array.
  *	  (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
  *	  is an extra restriction if not.)
+ *
+ * When allow_poly is false, we are not expecting any of the actual_arg_types
+ * to be polymorphic, and we should not return a polymorphic result type
+ * either.  When allow_poly is true, it is okay to have polymorphic "actual"
+ * arg types, and we can return ANYARRAY or ANYELEMENT as the result.  (This
+ * case is currently used only to check compatibility of an aggregate's
+ * declaration with the underlying transfn.)
  */
 Oid
 enforce_generic_type_consistency(Oid *actual_arg_types,
 								 Oid *declared_arg_types,
 								 int nargs,
-								 Oid rettype)
+								 Oid rettype,
+								 bool allow_poly)
 {
 	int			j;
 	bool		have_generics = false;
@@ -1268,9 +1276,6 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 	Oid			elem_typeid = InvalidOid;
 	Oid			array_typeid = InvalidOid;
 	Oid			array_typelem;
-	bool		have_anyelement = (rettype == ANYELEMENTOID ||
-								   rettype == ANYNONARRAYOID ||
-								   rettype == ANYENUMOID);
 	bool		have_anynonarray = (rettype == ANYNONARRAYOID);
 	bool		have_anyenum = (rettype == ANYENUMOID);
 
@@ -1287,7 +1292,7 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 			decl_type == ANYNONARRAYOID ||
 			decl_type == ANYENUMOID)
 		{
-			have_generics = have_anyelement = true;
+			have_generics = true;
 			if (decl_type == ANYNONARRAYOID)
 				have_anynonarray = true;
 			else if (decl_type == ANYENUMOID)
@@ -1297,6 +1302,8 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 				have_unknowns = true;
 				continue;
 			}
+			if (allow_poly && decl_type == actual_type)
+				continue;		/* no new information here */
 			if (OidIsValid(elem_typeid) && actual_type != elem_typeid)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
@@ -1314,6 +1321,8 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 				have_unknowns = true;
 				continue;
 			}
+			if (allow_poly && decl_type == actual_type)
+				continue;		/* no new information here */
 			if (OidIsValid(array_typeid) && actual_type != array_typeid)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
@@ -1335,20 +1344,12 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 	/* Get the element type based on the array type, if we have one */
 	if (OidIsValid(array_typeid))
 	{
-		if (array_typeid == ANYARRAYOID && !have_anyelement)
-		{
-			/* Special case for ANYARRAY input: okay iff no ANYELEMENT */
-			array_typelem = InvalidOid;
-		}
-		else
-		{
-			array_typelem = get_element_type(array_typeid);
-			if (!OidIsValid(array_typelem))
-				ereport(ERROR,
-						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("argument declared \"anyarray\" is not an array but type %s",
-								format_type_be(array_typeid))));
-		}
+		array_typelem = get_element_type(array_typeid);
+		if (!OidIsValid(array_typelem))
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("argument declared \"anyarray\" is not an array but type %s",
+							format_type_be(array_typeid))));
 
 		if (!OidIsValid(elem_typeid))
 		{
@@ -1370,13 +1371,21 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 	}
 	else if (!OidIsValid(elem_typeid))
 	{
-		/* Only way to get here is if all the generic args are UNKNOWN */
-		ereport(ERROR,
-				(errcode(ERRCODE_DATATYPE_MISMATCH),
-				 errmsg("could not determine polymorphic type because input has type \"unknown\"")));
+		if (allow_poly)
+		{
+			array_typeid = ANYARRAYOID;
+			elem_typeid = ANYELEMENTOID;
+		}
+		else
+		{
+			/* Only way to get here is if all the generic args are UNKNOWN */
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("could not determine polymorphic type because input has type \"unknown\"")));
+		}
 	}
 
-	if (have_anynonarray)
+	if (have_anynonarray && elem_typeid != ANYELEMENTOID)
 	{
 		/* require the element type to not be an array */
 		if (type_is_array(elem_typeid))
@@ -1386,7 +1395,7 @@ enforce_generic_type_consistency(Oid *actual_arg_types,
 						  format_type_be(elem_typeid))));
 	}
 
-	if (have_anyenum)
+	if (have_anyenum && elem_typeid != ANYELEMENTOID)
 	{
 		/* require the element type to be an enum */
 		if (!type_is_enum(elem_typeid))

src/backend/parser/parse_func.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_func.c,v 1.200 2008/01/01 19:45:51 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_func.c,v 1.201 2008/01/11 18:39:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -235,7 +235,8 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 	rettype = enforce_generic_type_consistency(actual_arg_types,
 											   declared_arg_types,
 											   nargs,
-											   rettype);
+											   rettype,
+											   false);
 
 	/* perform the necessary typecasting of arguments */
 	make_fn_arguments(pstate, fargs, actual_arg_types, declared_arg_types);

src/backend/parser/parse_oper.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_oper.c,v 1.100 2008/01/01 19:45:51 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_oper.c,v 1.101 2008/01/11 18:39:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1006,7 +1006,8 @@ make_scalar_array_op(ParseState *pstate, List *opname,
 	rettype = enforce_generic_type_consistency(actual_arg_types,
 											   declared_arg_types,
 											   2,
-											   opform->oprresult);
+											   opform->oprresult,
+											   false);
 
 	/*
 	 * Check that operator result is boolean
@@ -1116,7 +1117,8 @@ make_op_expr(ParseState *pstate, Operator op,
 	rettype = enforce_generic_type_consistency(actual_arg_types,
 											   declared_arg_types,
 											   nargs,
-											   opform->oprresult);
+											   opform->oprresult,
+											   false);
 
 	/* perform the necessary typecasting of arguments */
 	make_fn_arguments(pstate, args, actual_arg_types, declared_arg_types);

src/include/parser/parse_coerce.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/parser/parse_coerce.h,v 1.74 2008/01/01 19:45:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/parser/parse_coerce.h,v 1.75 2008/01/11 18:39:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -81,7 +81,8 @@ extern bool check_generic_type_consistency(Oid *actual_arg_types,
 extern Oid enforce_generic_type_consistency(Oid *actual_arg_types,
 								 Oid *declared_arg_types,
 								 int nargs,
-								 Oid rettype);
+								 Oid rettype,
+								 bool allow_poly);
 extern Oid resolve_generic_type(Oid declared_type,
 					 Oid context_actual_type,
 					 Oid context_declared_type);

src/test/regress/expected/polymorphism.out

@@ -577,3 +577,39 @@ select q2, sql_if(q2 > 0, q2, q2 + 1) from int8_tbl;
  -4567890123456789 | -4567890123456788
 (5 rows)
 
+-- another kind of polymorphic aggregate
+create function add_group(grp anyarray, ad anyelement, size integer)
+  returns anyarray
+  as $$
+begin
+  if grp is null then
+    return array[ad];
+  end if;
+  if array_upper(grp, 1) < size then
+    return grp || ad;
+  end if;
+  return grp;
+end;
+$$
+  language plpgsql immutable;
+create aggregate build_group(anyelement, integer) (
+  SFUNC = add_group,
+  STYPE = anyarray
+);
+select build_group(q1,3) from int8_tbl;
+        build_group         
+----------------------------
+ {123,123,4567890123456789}
+(1 row)
+
+-- this should fail because stype isn't compatible with arg
+create aggregate build_group(int8, integer) (
+  SFUNC = add_group,
+  STYPE = int2[]
+);
+ERROR:  function add_group(smallint[], bigint, integer) does not exist
+-- but we can make a non-poly agg from a poly sfunc if types are OK
+create aggregate build_group(int8, integer) (
+  SFUNC = add_group,
+  STYPE = int8[]
+);

src/test/regress/sql/polymorphism.sql

@@ -390,3 +390,39 @@ select case when $1 then $2 else $3 end $$ language sql;
 select f1, sql_if(f1 > 0, bleat(f1), bleat(f1 + 1)) from int4_tbl;
 
 select q2, sql_if(q2 > 0, q2, q2 + 1) from int8_tbl;
+
+-- another kind of polymorphic aggregate
+
+create function add_group(grp anyarray, ad anyelement, size integer)
+  returns anyarray
+  as $$
+begin
+  if grp is null then
+    return array[ad];
+  end if;
+  if array_upper(grp, 1) < size then
+    return grp || ad;
+  end if;
+  return grp;
+end;
+$$
+  language plpgsql immutable;
+
+create aggregate build_group(anyelement, integer) (
+  SFUNC = add_group,
+  STYPE = anyarray
+);
+
+select build_group(q1,3) from int8_tbl;
+
+-- this should fail because stype isn't compatible with arg
+create aggregate build_group(int8, integer) (
+  SFUNC = add_group,
+  STYPE = int2[]
+);
+
+-- but we can make a non-poly agg from a poly sfunc if types are OK
+create aggregate build_group(int8, integer) (
+  SFUNC = add_group,
+  STYPE = int8[]
+);