An approach to model and query event-based temporal data

Temporal database systems support all functions related to the management of large amounts of constantly changing data. However, current temporal database systems support a flat view of the history of data changes, in that all the changes are considered equally relevant and are, therefore, all stored in the database. However, many applications, such as monitoring and planning applications, call for more flexibility. Monitoring applications, in particular, may require that the history of a data item is stored only whenever a certain event occurs. For other applications, the history of data changes may be less important than the event causing the changes. In this paper, we propose an event-based temporal object model which allows us to keep track of selected values within the history of a data object attribute. The portions within the history of a data object which are actually stored in the database are identified by relating them to events. In the paper, besides defining the data model, we investigate the problem of querying a database with incomplete temporal information.