Showing papers on "Data access published in 1977"

The determination of efficient record segmentations and blocking factors for shared data files

Abstract: It is generally believed that 80 percent of all retrieval from a commercial database is directed at only 20 percent of the stored data items. By partitioning data items into primary and secondary record segments, storing them in physically separate files, and judiciously allocating available buffer space to the two files, it is possible to significantly reduce the average cost of information retrieval from a shared database. An analytic model, based upon knowledge of data item lengths, data access costs, and user retrieval patterns, is developed to assist an analyst with this assignment problem. A computationally tractable design algorithm is presented and results of its application are described.

Read request selection system for redundant storage

Abstract: There is provided, in accordance with the present invention, apparatus comprising a shared random access memory in which is stored requests for access to data in a bulk memory unit. The data being stored in redundant storage areas and the requests stored in the RAM include the address of the redundant data. Means are provided for determining if that data request is already in progress through one of the redundant addresses. The first of the addresses accessed causes the others to be blocked to prevent multiple accessing of the same data. The checking and selection is accomplished by high speed logic circuitry.

A Queueing Analysis of an Integrated Telecommunications system with Priorities

Abstract: In an integrated telecommunications system both voice and data compete for use of the same group of channels. Such a system allows for better use of the channels and more efficient use of the system facilities. Numerous operating rules for allowing voice and data access to the channels can be considered. In this paper, we give a steady state queueing analysis for two priority rules, voice pre-empting data and data pre-empting voice, when the mean service times of voice and data are different.

Managing Network Access to a Distributed Database

Abstract: : This paper describes a program, FAM--for File Access Manager--, used to access to data distributed over a computer network. FAM is part of a system which allows a casual user to express queries in a restricted subset of English, about a database of fourteen files stored redundantly on several Datacomputers. FAM is responsible for the data distribution aspects of the whole system: it establishes the network connections, decides which files in redundant groups to use, opens and closes them as needed. This paper presents some of the techniques which are used and discusses the limitations of this particular approach.

Concurrent access to data

Abstract: Problems caused by concurrent access to data can be solved by locking. This, however, diminishes efficiency and may cause deadlocks among the accessing processes. In this paper the structuring of data sets is deduced from assertions about accesses which may be performed simultaneously. This structuring supports the development of operations which synchronize concurrent access to these data. Thus the provisions for locking are transferred from programs to data structures where the requests for locking actually arise. The synchronization operations will exclude all undesired interferences and will maximize the number of possible simultaneous accesses in accordance with the original assertions.

Dispersion type data processing system

Abstract: PURPOSE:To increase speed and flexibility of data communication in the system in which a plural number of data processing units are linked with communicating lines, by making the data access directly not from the intelligence unit of opposing system.

A data-base system as a decision-taking aid in a cardiologic environment

Abstract: A software package is presented for the set up and management of archives of the definite population for clinical use. The archives accept both numeric data and free text. The package runs on a minicomputer system to allow the access to Data Base technology by small clinical groups. Besides the read/write facilities the system is oriented toward the extraction of user suggested and defined subsets of the population and their analysis.The Data structure has been defined so as to:—discharge the data-entry operator from non-relevant procedures and to maximize his performance.—leave the Data Base manager free to modify easily the previously defined data base and to up-grade with new not previously accepted variables.—accept data from direct recordings from the patient via automatic instrumentation.The system has been applied to a few different populations with related cardiovascular problems such as:(a) data from coronary arteriography, ventriculography, and other special cardiac examinations.(b) data from pa...