On Analyses of the Modified Versions of the Consecutive Retrieval File Organization

In information retrieval systems, the consecutive retrieval (CR) property enables the design of the system with a minimal search time and no redundant storage. However, the CR property cannot exist between every arbitrary query set and every record set unless we relax these restrictions. We use the variable-buffer quasi-CR (V-QCR) property scheme which tolerates variable buffer size in the main storage and several secondary storages. In secondary file organization, we propose two subschemes: 1) the relaxed CR (RCR) property subscheme which tolerates the duplication of records and multiple access, and 2) the CR property with dummy records (CR-D property) subscheme which tolerates the dummy records and the variable buffer size. For each proposed subscheme, we evaluate the trade-offs between the system redundancy and the loss of search time by rate-distortion theoretic approach. The result indicates that it is worthwhile to search for algorithms that will generate the secondary storage locations satisfying RCR and CR-D property subschemes, when the system size becomes sufficiently large.