Extending ATSQL to support temporally dependent information

Abstract

In temporal databases some attribute values depend on the associated timestamps while other attribute values are independent of them. An attribute is temporally independent if it has a value for a given time period and if this value also holds for periods contained in the original period. In contrast, the value of a temporally dependent attribute holds for the given time period only. Different values hold for its sub-periods. The completed database provides information for each sub-period of a database fact. In this paper we extend ATSQL to support temporally dependent information and report experiences from a prototype implementation.