Database operating efficiency in fragmented databases in mainframe, mini, and micro system environments

摘要

Vertical fragmentation in database design is the process of assigning attributes to physical segments to improve the database performance. Experiments were conducted to measure the performances of four Fragmentation design methods in the three hardware environments with six transaction mixes, using simulation and quantitative modelling. Some hypotheses are laid down regarding database performance and are validated. The MRGB design method which considered the hardware characteristics produced highest fragmentation in micro (IBM AT), and lowest in mini (Prime), with mainframe (IBM) in between. MRGB design performed the best in the three systems. The Hammer & Niamir's design did its best in mini (61%), and better in mainframe (50%) than in mini (41%) in low update environment. While the fully fragmented design performed the best in micro and the worst in mainframe, the unfragmented design performed the best in mini and the worst in micro.