TRANSACTION MANAGEMENT IN DESIGN DATABASES

Conventional data base systems are not suitable for handling advanced applications encountered in engineering, such as CAD/CAM, CASE, CAE, and VLSI design. The data bases in such environments, also called design data bases, are characterized by the presence of many complex data objects denoted by a large number of small tables, as opposed to a few large tables encountered in conventional data bases. The transaction model used in tracking data bases for banking, inventory control, and other such applications use view serializability as the correctness criterion. While view serializability is appropriate for tracking data bases, it is unnecessarily restrictive for engineering data bases. We propose a transaction model that is suitable for accessing shared design data based on coserializability. The transaction model supports long-duration transactions with intermediate commit points. In addition to the conventional nested transaction hierarchy, the model allows for cooperation between nested design transactions needed in a design environment.