Performance comparison of extendible hashing and linear hashing techniques

Abstract

Based on seven assumptions, the following comparison factors are used to compare the performance of linear hashing with extendible hashing: 1. storage utilization; 2. average unsuccessful search cost; 3. average successful search cost; 4. split cost; 5. insertion cost; 6. number of overflow buckets. The simulation is conducted with the bucket sizes of 10, 20, and 50 for both hashing techniques. In order to observe their average behavior, the simulation uses 50,000 keys which have been generated randomly. According to our simulation results, extendible hashing has an advantage of 5% over linear hashing in terms of storage utilization. Successful search, unsuccessful search, and insertions are less costly in linear hashing. However, linear hashing requires a large overflow space to handle the overflow records. Simulation shows that approximately 10% of the space should be marked as overflow space in linear hashing. Directory size is a serious bottleneck in extendible hashing. Based on the simulation results, the authors recommend linear hashing when main memory is at a premium.