Main{memory Linear Hashing { Some Enhancements of Larson's Algorithm

Linear Hashing has been proposed as a simple and eecient technique for storing and retrieving key sets whose cardinality is not known in advance. Its main advantage is that it allows tables to grow and shrink gracefully without major reorganizations. In this paper, several modiications of the basic scheme are presented, together with performance measurements. It is also shown that the seemingly{popular hashpjw hashing function presented in \the dragon book" can perform fairly poorly if the so{called randomizing mod operation is omitted. A simple and fast hashing function is presented that has performed well in this experiment. When combined, the algorithm changes presented here are shown to yield a performance improvement of roughly a factor of 4:5. The nal version is shown to be about 16% slower than a standard hash table using table doubling on overrow. A sample implementation is provided in the appendix.