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File definition and logical data independence

Published: 11 November 1971 Publication History

Abstract

This paper presents an architecture for a data base system which is capable of providing data independence at two levels, viz physical and logical. The architecture employs a schema, which gives an abstract picture of the physical data base, and a subschema, which contains the definitions of an application program's logical files. The language for writing these logical file definitions is then discussed, and a number of features which should be provided in such a language are identified, and descrioed. In particular it is shown that the language should include the quantifiers of the predicate calculus, and should be capable of defining files which span several files in the schema. The use of the subschema in providing logical data independence is then demonstrated, and an appropriate application program discipline discussed.
This is the first of two associated papers, the second of which deals with the complementary problems of storage structure and physical data independence.

References

[1]
C J Date, P Hopewell 'Storage Structures and Physical Data Independence' (companion paper submitted to the SIGFIDET workshop 1971).
[2]
H S Meltzer 'Data Base Concepts and an Architecture for a Data Base System' (section 4) IBM San Jose Programming Centre 20 August 1969.
[3]
Data Base Task Group Report to the CODASYL Programming Language Committee April 1971.
[4]
E F Codd 'A Relational Model of Data for Large Shared Data Banks' CACM Vol 13 No 6 June 1970.
[5]
E F Codd 'Further Normalization of the Relational Model' Courant Computer Science Symposia 6 'Data Base Systems' New York City, 24--25 May 1971. To be published by Prentice-Hall.
[6]
E F Codd 'A Data Base Sublanguage Founed on Relational Calculus' Proc 1971 ACM-SIGFIDET Workshop on Data Description, Access and Control, to be available from ACM HQ 1972.
[7]
'Information Management System/360' Application Description Manual IBM Form No. H20-0524 July 1968.
[8]
I J Heath 'Unacceptable File Operations in a Relational Data Base' Proc 1971 ACM-SIGFIDET Workshop on Data Description, Access and Control, to be available from ACM HQ 1972.

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cover image ACM Conferences
SIGFIDET '71: Proceedings of the 1971 ACM SIGFIDET (now SIGMOD) Workshop on Data Description, Access and Control
November 1971
368 pages
ISBN:9781450373005
DOI:10.1145/1734714
Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from [email protected]

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Association for Computing Machinery

New York, NY, United States

Publication History

Published: 11 November 1971

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