Evaluation of relational algebras incorporating the time dimension in databases
ACM Computing Surveys (CSUR)
Temporal databases: theory, design, and implementation
Temporal databases: theory, design, and implementation
Semantics of time-varying information
Information Systems
On the semantics of “now” in databases
ACM Transactions on Database Systems (TODS)
On the analysis of indexing schemes
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
SQL:1999: understanding relational language components
SQL:1999: understanding relational language components
The TSQL2 Temporal Query Language
The TSQL2 Temporal Query Language
Temporal and Real-Time Databases: A Survey
IEEE Transactions on Knowledge and Data Engineering
IEEE Transactions on Knowledge and Data Engineering
A Split Operator for Now-Relative Bitemporal Databases
Proceedings of the 17th International Conference on Data Engineering
Managing Intervals Efficiently in Object-Relational Databases
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Transaction Timestamping in (Temporal) Databases
Proceedings of the 27th International Conference on Very Large Data Bases
Coalescing in Temporal Databases
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Interval Processing with the UB-Tree
IDEAS '02 Proceedings of the 2002 International Symposium on Database Engineering & Applications
Layered Temporal DBMS: Concepts and Techniques
Proceedings of the Fifth International Conference on Database Systems for Advanced Applications (DASFAA)
Effective timestamping in databases
The VLDB Journal — The International Journal on Very Large Data Bases
Indexing of now-relative spatio-bitemporal data
The VLDB Journal — The International Journal on Very Large Data Bases
Temporal coalescing with now granularity, and incomplete information
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Modification semantics in now-relative databases
Information Systems
An algorithm for the difference between set covers
Discrete Applied Mathematics
Transaction time indexing with version compression
Proceedings of the VLDB Endowment
The POINT approach to represent now in bitemporal databases
Journal of Intelligent Information Systems
Encyclopedia of Database Systems
Encyclopedia of Database Systems
Indexing temporal data with virtual structure
ADBIS'10 Proceedings of the 14th east European conference on Advances in databases and information systems
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Now-relative temporal data play an important role in most temporal applications, and their management has been proved to impact in a crucial way the efficiency of temporal databases. Though several temporal relational approaches have been developed to deal with now-relative data, none of them has provided a whole temporal algebra to query them. In this paper we overcome such a limitation, by proposing a general algebra which is parametrically adapted to cope with the relational approaches to now-relative data in the literature, i.e., MIN, MAX, NULL and POINT approaches. Besides being general enough to provide a query language for several approaches in the literature, our algebra has been designed in such a way to satisfy several theoretical and practical desiderata: closure with respect to representation languages, correctness with respect to the "consensus" BCDM semantics, reducibility to the standard non-temporal algebra (which involves interoperability with non-temporal relational databases), implementability and efficiency. Indeed, the experimental evaluation we have drawn on our implementation has shown that only a slight overhead is added by our treatment of now-relative data (with respect to an approach in which such data are not present).