Scott T. Leutenegger

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In this paper we present the results from an extensive comparison study of three R-tree packing Mgorithms, including a new easy to implement Mgorithm. The algorithms are evaluated using both synthetic and actual data from various application domains including VLSI design, GIS (tiger), and computational fluid dynamics. Our studies also consider the ilnpact(More)
Scheduling policies for general purpose multiprogrammed multiprocessors are not well understood. This paper examines various policies to determine which properties of a scheduling policy are the most significant determinants of performance. We compare a more comprehensive set of policies than previous work, including one important scheduling policy that has(More)
A new iterative algorithm, the <italic>multi-level</italic> algorithm, for the numerical solution of steady state Markov chains is presented. The method utilizes a set of recursively coarsened representations of the original system to achieve accelerated convergence. It is motivated by multigrid methods, which are widely used for fast solution of partial(More)
The TPC-C benchmark is a new benchmark approved by the TPC council intended for comparing database platforms running a medium complexity transaction processing workload. Some key aspects in which this new benchmark differs from the TPC-A benchmark are in having several transaction types, some of which are more complex than that in TPC-A, and in having data(More)
We present a new approach for approximate nearest neighbor queries for sets of high dimensional points under any L t-metric, t = 1; : : : ; 1. The proposed algorithm is eecient and simple to implement. The algorithm uses multiple shifted copies of the data points and stores them in up to (d + 1) B-trees where d is the dimensionality of the data, sorted(More)
The evaluation of parallel job schedulers hinges on the work-loads used. It is suggested that this be standardized, in terms of both format and content, so as to ease the evaluation and comparison of different systems. The question remains whether this can encompass both traditional parallel systems and metacomputing systems. This paper is based on a panel(More)
CM-line loading of R-trees is useful to improve node utilization and query performance. WTepresent an algorithm for bulk loading R-trees -r&id diifers horn previous ones in two aspects (a) it partitions input data into subtrees in a top-down fashion (based on the fact that splits close to the root are likely to have a greater impact on performance), (b) at(More)
ÐPast R-tree studies have focused on the number of nodes visited as a metric of query performance. Since database systems usually include a buffering mechanism, we propose that the number of disk accesses is a more realistic measure of performance. We develop a buffer model to analyze the number of disk accesses required for spatial queries using R-trees.(More)
In this paper we argue for using a "Game First" approach to teaching introductory programming. We believe that concerns over whether an OO approach or a procedural approach should be used first are secondary to the course assignment and example content. If examples are not compelling, student interest often lags thus making the OO versus procedural argument(More)