gistfile1.txt

diff --git a/mysql_pool/base.py b/mysql_pool/base.py
index b8be24f..5548602 100644
--- a/mysql_pool/base.py
+++ b/mysql_pool/base.py
@@ -27,7 +27,10 @@ Database = manage(Database, **getattr(settings, 'DATABASE_POOL_ARGS', {}))
 def serialize(**kwargs):
     # We need to figure out what database connection goes where
     # so we'll hash the args.
-    return hashlib.md5(str(kwargs)).hexdigest()
+    keys = sorted(kwargs.keys())
+    out = [repr(k) + repr(kwargs[k])
+           for k in keys if isinstance(kwargs[k], (str, int, bool))]
+    return hashlib.md5(''.join(out)).hexdigest()
 
 
 class DatabaseWrapper(DatabaseWrapper):
@@ -61,15 +64,12 @@ class DatabaseWrapper(DatabaseWrapper):
         # SQL Alchemy can't serialize the dict that's in OPTIONS, so
         # we'll do some serialization ourselves. You can avoid this
         # step specifying sa_pool_key in the DB settings.
-        if 'sa_pool_key' not in kwargs:
-            kwargs['sa_pool_key'] = serialize(**kwargs)
-        self._settings_dict = kwargs
+        kwargs['sa_pool_key'] = serialize(**kwargs)
+        return kwargs
 
     def _cursor(self):
-        if not getattr(self, '_settings_dict', None):
-            self._set_settings()
-
-        self.connection = Database.connect(**self._settings_dict)
+        settings = self._set_settings()
+        self.connection = Database.connect(**settings)
         self.connection.encoders[SafeUnicode] = self.connection.encoders[unicode]
         self.connection.encoders[SafeString] = self.connection.encoders[str]
         connection_created.send(sender=self.__class__, connection=self)