Bug # 403 http://bugs.skysql.com/show_bug.cgi?id=403
Comparing the return value of atomic_add instead of buffer's reference count variable.
Support for mysql session variable commands, for example, SET AUTOCOMMIT=0
Session commands are identified by query clasisfier, and added to the session command property list in router client session object.
Session commands are then executed in existing backend servers but only one of them will reply to client.