Supporting historical references is an important problem in several areas of computer science and engineering. The significance of the database versioning problem (i.e., keeping and accessing old versions) has been particularly mentioned in recent advances in the database community. In the rapidly growing area of object oriented programming, historical references enable programmers to create new objects based on previous object versions. Traditional approaches to supporting historical references require either large space or long reconstruction times, making the extensive use of such references prohibitive. This project provides efficient support of historical references, i.e., fast reconstruction to any past state without sacrificing a large amount of storage space. New, optimal ways are investigated to compress temporal data, while still providing practically random access to any past reference on these data. Moreover, the problems of distributing the history, keeping the history of a system that evolves like a graph, keeping histories in limited space and other general historical queries (not indexed by time but instead using historical correlation) are analyzed. The results of this project will greatly impact the use of the recorded past history for different programmers or database users. Other applications of these results to be considered, include network management tools, animation storing and archiving the UNIX directory system.
