Horizontal fragmentation may improve the performance of database systems. Defining primary and derived horizontal fragmentation along the classes in a database schema is an important and complex issue, yet not discussed in the literature, which must be considered when horizontally fragmenting a database. In this paper, we focus on an analysis to help the designer upon the decision for primary or derived horizontal fragmentation. This analysis considers performance results of distributed databases using horizontal fragmentation to evaluate the potential benefits and drawbacks of primary and derived techniques. Therefore, this work presents a horizontal fragmentation algorithm that chooses the most adequate strategy (primary or derived) based on class relationships, single class access and query access frequencies 1 Introduction Horizontal fragmentation is often used as a means to achieve better performance of database systems by reducing the disk access required to execute an applicat...

This work presents the application of theory revision to the design of distributed databases to automatically revise a heuristic-based algorithm (called analysis algorithm) through the use of the FORTE system. The analysis algorithm decides the fragmentation technique to be used in each class of the database and its Prolog implementation is provided as the initial domain theory. Fragmentation schemas...