The nested-inherited index has been recently proposed a san access structure providing an integrated support for querce in object-oriented databases along both aggregation and inheritance hierarchies. It is very efficient for retrieval operations. However, its high update costs make this structure suitable only for hierarchies with a small number of classes. In this paper we propose an enhanced nested-inherited index, able to support update operations more efficiently, whereas supporting nested predicates as efficiently as the nested-inherited index. The new organization supports the construction of several index allocation strategies, from which the most efficient with respect to a given workload can be selected. The new and old indices are compared using an analytical cost model. Results of the analysis show that the enhanced nested-inherited index provides superior performance than the inherited-multiindex and nested-inherited index.
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