A model of atomicity for multilevel transactions

Data management applications that use multilevel database management system (DBMS) capabilities have the requirement to read and write objects at multiple levels within the bounds of a multilevel transaction. The authors define a new notion of atomicity that is meaningful within the constraints of the multilevel environment. They offer a model of multilevel atomicity that defines varying degrees of atomicity and recognizes that lower security level operations within a transaction must be able to commit or abort independently of higher security level operations. Execution graphs are provided as a tool for analyzing atomicity requirements in conjunction with internal semantic interdependencies among the operations of a transaction and rules for determining the greatest degree of atomicity are proved that can be attained for a given multilevel transaction. Several alternative transaction management algorithms that can be used to preserve multilevel atomicity are presented