A dynamic hash method with signature

Abstract

We present a dynamic external hash method that allows retrieval of a record by only one access to mass storage while maintaining a high load factor. The hash function is based on generalized spiral storage. Both primary and overflow records are allocated to the same file, and file expansion depends on being able to allocate every overflow chain to one bucket. An in-core index, built by means of a signature function, discriminates between primary and overflow records and assures one access to storage in the case of either successful or unsuccessful searching. Simulation results confirm the good expected performance.