diff --git a/colddb.lua b/colddb.lua
index 593a93e..29e657c 100644
--- a/colddb.lua
+++ b/colddb.lua
@@ -264,6 +264,12 @@ function colddb.Colddb(dir)
 			delete_file(name)
 		end
 	end
+
+	self.sub_database = function(path)
+		local db = colddb.Colddb(dir .. "/" .. path)
+		db.set_async(async)
+		return db
+	end
 	
 	return self
 end