A Heuristic Approach to Cost-Efficient Derived Horizontal Fragmentation of Complex Value Databases

Derived horizontal fragmentation is one of the main database distribution design techniques. Unlike primary horizontal fragmentation, the decision of derived horizontal fragmentation is not straightforward. In the literature, in the context of the relational model, derived horizontal fragmentation of a member relation is achieved by performing semijoins with fragments of one of its owner relations, which is chosen in an ad hoc manner without evaluating the system performance. Similar approaches are found in the literature for the object oriented data model. We note that fragmentation and allocation are often considered separately, disregarding that they are using the same input information to achieve the same objective, i.e. improve the overall system performance. This paper addresses derived horizontal fragmentation and allocation simultaneously in the context of complex data model. The core of the paper is a heuristic approach to derived horizontal fragmentation, which uses a cost model and is targeted at globally minimising costs.