What does the value -1 represent in the PRIVILEGEMASK field ?
The PRIVILEGES System table contains information about privileges for users and tables in your database. One of the fields, PRIVILEGEMASK, is described here. When PRIVILEGEMASK field is "-1", it means all privileges are enabled / granted (existing and future ones).
It is used to indicate that the holder object is the owner of the other object. If a new privilege is added in a future NuoDB version on the object type of the owned object, its owner gets it automatically.