2991	 Improving the Access Time for Random Access Files	 Clustering in the key set is decreased by smoothing the key-to-address transformation and by adding shadow buckets to an open chaining file. The keys are pre-hashed before the address division to remove the effect of sequential properties in the key set. Shadow buckets in the key search sequence reduce the effect of nonuniformity in file loading and decrease the number of maximum probes needed to locate a record. The combined effects of these techniques lead to improved file performance for secondary storage devices as shown by empirical studies. hashing hashing techniques hashing methods hash coding keys key transformation key-to-address transformation direct addressing direct access direct access method randomizing random access file addressing file organizations file structures scatter storage search method collisions synonyms clustering information retrieval open addressing open chaining buckets bucket size shadow buckets combinatorics
