Declustering techniques for parallelizing temporal access structures

This paper addresses the issues of declustering temporal index and access structures for a single processor multiple independent disk architecture. The temporal index is the Monotonic B⁺-Tree which uses the time index temporal access structure. We devise a new algorithm, called multi-level round robin, for assigning tree nodes to multiple disks. The multi-level round robin declustering technique takes advantage of the append-only nature of temporal databases to achieve uniform load distribution, decrease response time, and increase the fanout of the tree by eliminating the need to store disk numbers within the tree nodes. We propose two declustering techniques for the time index access structures; one considers only time proximity while declustering, whereas the other considers both time proximity and data size. We investigate their performance over different types of temporal queries and show that various temporal queries have conflicting allocation criteria for the time index buckets. In addition, we devise two disk partition techniques for the time index buckets. The mutually exclusive technique partitions the disks into disjoint groups, whereas the shared disk technique allows the different types of buckets to share all disks