Analysis of indexed sequential and direct access file organizations

Abstract

A computer systems designer is faced with a decision concerning the organization of data files.He often would like to design a file so that sequential and random processing can both be performed efficiently.Two file organizations often proposed for these processing requirements are indexed sequential and direct. Another technique called "batch random" has been proposed for the batch updating of direct access files.Discrete simulation models of these file organizations and access methods in both transaction and batch processing modes are developed and used to analyze the file organizations.A general guideline is derived to indicate whether batch or transaction processing should be performed based on the percentage of the file which is to be processed.Based on these results, a methodology for selecting the "best" file organization is developed for a given set of criteria.Not all the parameters for describing a file organization are incorporated into the methodology and therefore "best" does not necessarily mean optimal. 389

Analysis of index-sequential files with overflow chaining

“…(2) The stochastic process defined above is an instance of a more general birth and death process studied by W. Feller, D. G. Kendall, and several other authors in the forties and fifties [4,111. The general birth and death process has found applications in many different areas, including queuing theory, power supply, and telephone traffic.…”

“…Wong and Strauss [14] developed a fairly detailed analytical model of IBM's index-sequential access method (ISAM). Behymer, Ogilive, and Merten [2] compare the performance of index-sequential and hash files by simulation. The file evaluation system FOREM by Sex&o, Lum, and Owens [12] also included index-sequential files.…”