Add ALTER DOMAIN ... RENAME

You could already rename domains using ALTER TYPE, but with this new
command it is more consistent with how other commands treat domains as
a subcategory of types.

src/backend/commands/alter.c

@@ -134,8 +134,9 @@ ExecRenameStmt(RenameStmt *stmt)
 			RenameTSConfiguration(stmt->object, stmt->newname);
 			break;
 
+		case OBJECT_DOMAIN:
 		case OBJECT_TYPE:
-			RenameType(stmt->object, stmt->newname);
+			RenameType(stmt);
 			break;
 
 		default:

src/backend/commands/typecmds.c

@@ -3074,8 +3074,10 @@ GetDomainConstraints(Oid typeOid)
  * Execute ALTER TYPE RENAME
  */
 void
-RenameType(List *names, const char *newTypeName)
+RenameType(RenameStmt *stmt)
 {
+	List	   *names = stmt->object;
+	const char *newTypeName = stmt->newname;
 	TypeName   *typename;
 	Oid			typeOid;
 	Relation	rel;
@@ -3099,6 +3101,13 @@ RenameType(List *names, const char *newTypeName)
 		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_TYPE,
 					   format_type_be(typeOid));
 
+	/* ALTER DOMAIN used on a non-domain? */
+	if (stmt->renameType == OBJECT_DOMAIN && typTup->typtype != TYPTYPE_DOMAIN)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a domain",
+						format_type_be(typeOid))));
+
 	/*
 	 * If it's a composite type, we need to check that it really is a
 	 * free-standing composite type, and not a table's rowtype. We want people

src/backend/parser/gram.y

@@ -6451,6 +6451,14 @@ RenameStmt: ALTER AGGREGATE func_name aggr_args RENAME TO name
 					n->newname = $6;
 					$$ = (Node *)n;
 				}
+			| ALTER DOMAIN_P any_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_DOMAIN;
+					n->object = $3;
+					n->newname = $6;
+					$$ = (Node *)n;
+				}
 			| ALTER FOREIGN DATA_P WRAPPER name RENAME TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);

src/include/commands/typecmds.h

@@ -37,7 +37,7 @@ extern void AlterDomainDropConstraint(List *names, const char *constrName,
 
 extern List *GetDomainConstraints(Oid typeOid);
 
-extern void RenameType(List *names, const char *newTypeName);
+extern void RenameType(RenameStmt *stmt);
 extern void AlterTypeOwner(List *names, Oid newOwnerId);
 extern void AlterTypeOwnerInternal(Oid typeOid, Oid newOwnerId,
 					   bool hasDependEntry);

src/test/regress/expected/domain.out

@@ -648,3 +648,10 @@ select array_elem_check(-1);
 ERROR:  value for domain orderedpair violates check constraint "orderedpair_check"
 CONTEXT:  PL/pgSQL function "array_elem_check" line 5 at assignment
 drop function array_elem_check(int);
+--
+-- Renaming
+--
+create domain testdomain1 as int;
+alter domain testdomain1 rename to testdomain2;
+alter type testdomain2 rename to testdomain3;  -- alter type also works
+drop domain testdomain3;

src/test/regress/sql/domain.sql

@@ -483,3 +483,13 @@ select array_elem_check(3);
 select array_elem_check(-1);
 
 drop function array_elem_check(int);
+
+
+--
+-- Renaming
+--
+
+create domain testdomain1 as int;
+alter domain testdomain1 rename to testdomain2;
+alter type testdomain2 rename to testdomain3;  -- alter type also works
+drop domain testdomain3;