1. A method of managing a directory for a database system having an in-memory database, comprising: receiving a user request to access a database object stored in a permanent memory-based database; in response to receiving the user request, searching an in-memory database to determine if the requested database object is also stored in the in-memory database; in response to receiving the user request, searching a directory comprising a plurality of directory entries to determine if a directory entry exists for the requested database object, wherein each directory entry corresponds to one of a plurality of stored database objects and indicates if the stored database object is to be accessed in the permanent memory-based database or in the in-memory database; in response to determining that the requested database object is also stored in the in-memory database and that a directory entry exists for the requested database object, determining if the directory entry indicates if the requested database object is to be accessed in the in-memory database, and if not, updating the directory entry to indicate that the requested database object is to be accessed in the in-memory database.