Abstract Index Interfaces

An index in a database system interacts with many of the software modules in the system. For systems supporting a wide range of index structures, interfacing the index code with the rest of the system poses a great problem. The problems are an order of magnitude more for adding new access methods to the system. These problems could be reduced manifold if common interfaces could be specified for different access methods. It would be even better, if these interfaces could be made database-system independent. This thesis addresses the problem of defining generic index interfaces for access methods in database systems. It concentrates on two specific issues: First, specification of a complete set of abstract interfaces that would work for all access methods and for all database systems. Second, optimized query processing for all data types including userdefined data types. An access method in a database system can be considered to be made up of three specific parts: Upper interfaces, lower interfaces, and type interfaces. An access method interacts with a database system through its upper interfaces, lower interfaces and type interfaces. Upper interfaces consist of the functions an index provides to a database system. Lower interfaces are the database-system dependent software modules an index has to interact with, to accomplish any system related functions. Type interfaces consist of the set of functions an index uses, which interpret the data type. These three parts together characterize an access method in a database system. This splitting of an access method makes it possible to define generic interfaces. In this thesis, we will discuss each of these three different interfaces in detail, identify functionalities and design clear interfaces. The design of these interfaces promote development of type-independent and database-system independent access methods