Twin grid files: A performance evaluation

Data structures for the physical organization of multidimensional points on secondary storage usually suffer from a fairly low average storage space utilization, even for independently and uniformly distributed points. We evaluate the performance of two types of space optimizing access schemes, the optimal static and the suboptimal dynamic twin grid files. It turns out that in comparison with the (standard) grid file, twin grid files achieve considerable savings in storage space, without losing efficiency in any other relevant aspect. This is shown to hold for typical operations in a variety of practical situations. To better grasp the inherent power of twin grid files, variations of crucial parameter settings are studied in detail.