An Access Path Specification Language for Restructuring Network Databases.

摘要

Current approaches to restructuring are based on the hierarchical data model and use specific operations to achieve the required transformations. The writer's approach to restructuring the class of network data bases has three principal characteristics: data model - the Relational Interface Model permits the data base to be viewed simultaneously as a network data base and a relational data base in first normal form; Restructuring System, which can perform the operations of the relational algebra but is not restricted to any data model dependent operations, and which can perform in a simple, efficient manner, user-required network transformations such as link record processing; and Access Path Specification Language - APSL - is a verifiably powerful, structurally simple, and descriptive language. The access path approach permits the specification of complex restructuring transformations in terms of application-oriented concepts such as access strategies and selection criteria. A high-level Access Path Restructuring Language (APSL) based on this approach is presented, and an example of its use in restructuring is given.