Research and Advances

Analysis and performance of inverted data base structures

The need to envision and architecture data base systems in a hierarchical level by level framework is stressed. The inverted data base (file) organization is then analyzed, considering implementation oriented aspects. The inverted directory is viewed realistically as another large data base which itself is subjected to inversion. Formulations are derived to estimate average access time (read only) and storage requirements, formalizing the interaction of data base content characteristics, logical complexity of queries, and machine timing and blocking specifications identified as having a first-order effect on performance. The formulations presented are necessary to be used in conjunction with any index selection criteria to determine the optimum set of index keys.

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Research and Advances

Evaluation and selection of file organization—a model and system

This work first discusses the factors that affect file (data base) organization performance, an elusive subject, and then presents a methodology, a model and a programmed system to estimate primarily total storage costs and average access time of several file organizations, given a specific data base, query characterization and device-related specifications. Based on these estimates, an appropriate file structure may be selected for the specific situation. The system is a convenient tool to study file structures and to facilitate as much as possible the process of data base structure design and evaluation.
Research and Advances

PDEL—a language for partial differential equations

Conventional computer methods available to solve continuous system problems characterized by partial differential equations are very time-consuming and cumbersome. A convenient, easy to learn and to use, high level problem oriented language to solve and study partial differential equation problems has been designed; a practical translator for the language has also been designed, and a working version of it has been constructed for a significant portion of the language. This Partial Differential Equation Language, PDEL, is outlined, and the highlights of the translator are briefly summarized.

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