Bitemporal Databases

All mainstream database systems lack support for temporal metadata, and instead store only the most recent data. Consequently, they can only manage temporal data in an ad hoc manner -- oftentimes not effectively. Yet there are countless application domains that need temporal data. This book offers a much-needed solution: It includes a bitemporal relational data model, based on nested relations, as well as its algebra and calculus languages for expressing queries. The fundamental construct for representing temporal data is a bitemporal atom; a value, its validity period, and the time this data was recorded in the database. The concept of context defines different views of bitemporal data. BtSQL, a simple bitemporal variation of the SQL, is introduced. The book also provides a prototype implementation, which demonstrates the feasibility of the proposed approach in an object-relational database system. Researchers and practitioners in database development will find this book useful. It can be used as a textbook in advanced database courses -- particularly in application domains where temporal metadata can greatly leverage the value of the data as it is stored and utilized.