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Issue No. 02 - April (1992 vol. 4)
ISSN: 1041-4347
pp: 192-200
<p>A data model that allows for the storage of detailed change history in so-called backlog relations is described. Its extended relational algebra, in conjunction with the extended data structures, provides a powerful tool for the retrieval of patterns and exceptions in change history. An operator, Sigma , based on the notion of compact active domain is introduced. It groups data not in predefined groups but in groups that fit the data. This operator further expands the retrieval capabilities of the algebra. The expressive power of the algebra is demonstrated by examples, some of which show how patterns and exceptions in change history can be detected. Sample applications of this work are statistical and scientific databases, monitoring (of databases, manufacturing plants, power plants, etc.), CAD, and CASE.</p>
statistical databases; extended relational model; detailed change history; backlog relations; relational algebra; data structures; patterns; exceptions; compact active domain; scientific databases; CAD; CASE; data structures; error handling; relational databases

L. Mark and C. Jensen, "Queries on Change in an Extended Relational Model," in IEEE Transactions on Knowledge & Data Engineering, vol. 4, no. , pp. 192-200, 1992.
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