[SQL]allow to use aggregate

src/gausskernel/process/tcop/utility.cpp

@@ -3795,12 +3795,12 @@ void standard_ProcessUtility(Node* parse_tree, const char* query_string, ParamLi
 
             switch (stmt->kind) {
                 case OBJECT_AGGREGATE:
-#ifdef PGXC
+#ifdef  ENABLE_MULTIPLE_NODES
                     if (!u_sess->attr.attr_common.IsInplaceUpgrade && !u_sess->exec_cxt.extension_is_valid)
                         ereport(ERROR,
                             (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("user defined aggregate is not yet supported.")));
-#endif /* PGXC */
+#endif /*  ENABLE_MULTIPLE_NODES */
                     DefineAggregate(stmt->defnames, stmt->args, stmt->oldstyle, stmt->definition);
                     break;
                 case OBJECT_OPERATOR:
@@ -8547,9 +8547,11 @@ void CheckObjectInBlackList(ObjectType obj_type, const char* query_string)
                 return;
             else
                 break;
+#ifdef ENABLE_MULTIPLE_NODES
         case OBJECT_AGGREGATE:
             tag = "AGGREGATE";
             break;
+#endif
         case OBJECT_OPERATOR:
             tag = "OPERATOR";
             break;

src/test/regress/expected/errors.out

@@ -126,12 +126,12 @@ create aggregate newavg2 (sfunc = int4pl,
 			  stype = int4,
 			  finalfunc = int2um,
 			  initcond = '0');
-ERROR:  user defined aggregate is not yet supported.
+ERROR:  function int2um(smallint) requires run-time type coercion
 -- left out basetype
 create aggregate newcnt1 (sfunc = int4inc,
 			  stype = int4,
 			  initcond = '0');
-ERROR:  user defined aggregate is not yet supported.
+ERROR:  aggregate input type must be specified
 --
 -- DROP INDEX
 -- missing index name

src/test/regress/expected/single_node_errors.out

@@ -127,12 +127,12 @@ create aggregate newavg2 (sfunc = int4pl,
 			  stype = int4,
 			  finalfunc = int2um,
 			  initcond = '0');
-ERROR:  user defined aggregate is not yet supported.
+ERROR:  function int2um(smallint) requires run-time type coercion
 -- left out basetype
 create aggregate newcnt1 (sfunc = int4inc,
 			  stype = int4,
 			  initcond = '0');
-ERROR:  user defined aggregate is not yet supported.
+ERROR:  aggregate input type must be specified
 --
 -- DROP INDEX
 -- missing index name