Temporal Databases

A temporal database provides for management of time-varying data through the explicit support of one or more time dimensions. Time is a fundamental important aspect of several real world phenomena and the ability to capture the evolutionary nature of data and to model changes occurring in the real world is an essential requirement of advanced database applications. A temporal database enables the representation of time-stamped data, the maintenance of their history through non destructive updates and the subsequent possibility to access and query such histories. A substantial research effort has been done on temporal databases since the early 1980’s gathering through the decades a crop of proposals and results, as is witnessed by a quite large literature. Temporal extensions of data models and query languages have been defined but also extensions required to any other components of database technology have been studied in this field. Remarkable collective initiatives lead to the definition of a consensual glossary of temporal database concepts to be shared by the scientific community and to the design of an extension of the SQL query language by a committee of temporal database experts. Temporal database studies have also entered into practice, as mainstream commercial DBMSs currently include some support for time-stamped data and the latest SQL:2011 standard provides for temporal constructs.