Abstract. A challenging question is how XML can be used to support distributed databases. This leads to the problem of how to obtain a suitable, cost-efficient distribution design for XML documents. In this paper we sketch a heuristic approach to minimise query costs for the case of horizontal fragmentation. The approach is based on a cost model that takes the complex structure of queries on XML documents into account. We show that the minimisation of transportation costs is decisive, and that this can be achieved locally by either accepting or rejecting a horizontal fragmentation with a simple predicate that arises from one of the most frequent queries. 1

{richard.chbeir, kokou.yetongnon} @ u-bourgogne.fr Abstract. Database fragmentation is a process for reducing irrelevant data accesses by grouping data frequently accessed together in dedicated segments. In this paper, we address multimedia database fragmentation by extending existing fragmentation algorithms to take into account key characteristics of multimedia objects. We particularly discuss multimedia primary horizontal fragmentation and provide a partitioning strategy based on low-level multimedia features. Our approach particularly emphasizes the importance of multimedia predicates implications in optimizing multimedia fragments. To validate our approach, we have implemented a prototype computing multimedia predicates implications. Experimental results are satisfactory.

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