151. Temporal Extension of Relational Algebra
- Author
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Shu Li, Pan Shi, Yong Tang, and Dongning Liu
- Subjects
Relational calculus ,Theoretical computer science ,Relation (database) ,Computer science ,Codd's theorem ,Relational model ,Domain relational calculus ,Relational algebra ,Tuple ,Temporal database - Abstract
Temporal relational operations can be considered as temporal extensions of regular relational operations, which are the basic contents of temporal database technology. Like traditional relational operations, temporal relational operations can also be classified into two types: temporal relational algebra and temporal relational calculus. The former takes relation as a set of tuples, while the latter uses temporal predicates to select temporal tuples, which should meet not only the requirements in terms of attributes but also temporal predicates. In this chapter, first the regular relational operations are reviewed. Subsequently, temporal relational operations based on historical relational database model (HRDM) and bitemporal conceptual data model (BCDM) are discussed. Finally, three important properties—snapshot reducibility, temporal semi-completeness, and temporal completeness are introduced.
- Published
- 2010