Incremental Maintenance of Data Warehouses Based on Past Temporal Logic Operators
Дата
Авторы
De Amo,Sandra
Alves,Mírian Halfeld Ferrari
Journal Title
Journal ISSN
Volume Title
Издатель
Journal of Universal Computer Science
Аннотация
Описание
We see a temporal data warehouse as a set of temporal views defined in the past fragment of the temporal relational algebra extended with set-valued attributes and aggregation. This paper proposes an incremental maintenance method for temporal views that allows improvements over the re-computation from scratch. We introduce a formalism for temporal data warehouse specification that summarizes information needed for its incremental maintenance. According to this formalism, a temporal data warehouse W is a pair of two sets of views : the materialized component and the virtual component. The materialized component of W represents the set of views physically stored in the warehouse. The virtual component of W is a set of non-temporal expressions involving only relations kept in the materialized component. Several features of our approach make it especially attractive as a maintenance method for warehouses: (a) there is no need for storing the entire history of source databases, (b) maintenance of the temporal data warehouse is reduced to maintaining the (non-temporal) materialized component, and (c) the materialized component is self-maintainable. We build a uniform algorithm by combining two previously unrelated techniques based on auxiliary views. Our method is sufficiently general so that it can be easily adapted to treating databases with complex-valued attributes.
Ключевые слова
temporal data warehouse , temporal databases , temporal relational algebra , temporal logic , self-maintenance