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| This paper addresses the problem of urgently needed data management techniques for eeciently retrieving requested subsets of large datasets from mass storage devices. This problem is especiallycritical for scientiic investigatorswho need ready access to the large volume of data generated by large-scale supercomputer simulations and physical experiments as(More)
This paper reviews recent literature on techniques for obtaining random samples from databases. We begin with a discussion of why one would want to include sampling facilities in database management systems. We then review basic sampling techniques used in construct-join are then described. We then describe sampling for estimation of aggregates (e.g., the(More)
In this paper we propose a new declustering method which is particularly suitable for image and cartographic databases used for visualization. Our declustering method is based on algebraic techniques using vectors. The algorithm which computes the disk assignment requires O(Kj log K) time where K is the number of parallel disks in the system. The resulting(More)
In this paper, we propose a new strategy for optimizing the placement of bin boundaries to minimize the cost of query evaluation using bitmap indices with binning. For attributes with a large number of distinct values, often the most efficient index scheme is a bitmap index with binning. However, this type of index may not be able to fully resolve some user(More)