Multidatabase Systems: An Advanced Concept in Handling Distributed Data

Publisher Summary Multidatabases integrate the data from preexisting, heterogeneous local databases into a distributed environment, and present global users with transparent methods to use the total information in the system. This chapter describes the taxonomy of global information-sharing systems, multidatabase issues, multidatabse design choices, analysis of existing multidatabase systems, and the position of multidatabase systems in the taxonomy. Multidatabase language systems have no constraints on system size, but the tradeoff for achieving this is a multiple-data-source user paradigm and a more complex user interface. Multidatabase issues, such as site autonomy, differences in data representation, and concurrency control are also discussed in the chapter. Site autonomy is a major strength of multidatabases, yet it is also a major constraint on the global system design. Differences in data representation are many and varied, and resolving these differences is a major concern of the global system design. Global updates are a major current restriction in many systems, and the focus of much current research. To make multidatabase systems more useful and efficient, some deficiencies in existing prototypes must be resolved before they can evolve into commercial products, such as global concurrency control, global security, maintenance and administration, and error control and recovery. Multidatabase systems should begin to have a larger impact in the information-processing world as more powerful systems to become generally available in the near future.