US Patent 10185726 Access control for nested data fields

Systems, computer program products and methods implementing access control for compound structures including subfields are described. A policy system receives a database schema and a data access policy. The database schema defines multiple subfields of a data column. The policy includes one or more rules limiting access to the subfields. A policy analyzer of the policy system creates an access control metadata that stores correspondence between the subfields and the rules. The policy analyzer represents the subfields in the access control metadata using relations between subfields and other components of the database. The policy analyzer provides the access control metadata to a policy enforcer for enforcing the policy on the subfields.