TY - JOUR
T1 - A comprehensive approach to 'now' in temporal relational databases
T2 - Semantics and representation
AU - Anselma, Luca
AU - Piovesan, Luca
AU - Sattar, Abdul
AU - Stantic, Bela
AU - Terenziani, Paolo
N1 - Publisher Copyright:
© 1989-2012 IEEE.
PY - 2016/10
Y1 - 2016/10
N2 - Now-related temporal data play an important role in many applications. Clifford et al.'s approach is a milestone to model the semantics of 'now' in temporal relational databases. Several relational representation models for now-related data have been presented; however, the semantics of such representations has not been explicitly studied. Additionally, the definition of a relational algebra to query now-related data is an open problem. We propose the first integrated approach that provides both a neat semantics for now-related data and a compact 1NF representation (data model and relational algebra) for them. Additionally, our approach also extends current approaches to consider (i) domains where it is not always possible to know when changes in the world are recorded in the database and (ii) now-related data with a bound on their persistency in the future. To do so, we explicitly model the notion of temporal indeterminacy in the future for now-related data. The properties of our approach are also analyzed both from a theoretical (semantic correctness and reducibility of the algebra) and from an experimental point of view. Experiments show that, despite the fact that our approach is a major extension to current temporal relational approaches, no significant overhead is added to deal with 'now'.
AB - Now-related temporal data play an important role in many applications. Clifford et al.'s approach is a milestone to model the semantics of 'now' in temporal relational databases. Several relational representation models for now-related data have been presented; however, the semantics of such representations has not been explicitly studied. Additionally, the definition of a relational algebra to query now-related data is an open problem. We propose the first integrated approach that provides both a neat semantics for now-related data and a compact 1NF representation (data model and relational algebra) for them. Additionally, our approach also extends current approaches to consider (i) domains where it is not always possible to know when changes in the world are recorded in the database and (ii) now-related data with a bound on their persistency in the future. To do so, we explicitly model the notion of temporal indeterminacy in the future for now-related data. The properties of our approach are also analyzed both from a theoretical (semantic correctness and reducibility of the algebra) and from an experimental point of view. Experiments show that, despite the fact that our approach is a major extension to current temporal relational approaches, no significant overhead is added to deal with 'now'.
KW - Temporal databases
KW - database design
KW - modeling and management
UR - http://www.scopus.com/inward/record.url?scp=84990978727&partnerID=8YFLogxK
U2 - 10.1109/TKDE.2016.2588490
DO - 10.1109/TKDE.2016.2588490
M3 - Article
SN - 1041-4347
VL - 28
SP - 2538
EP - 2551
JO - IEEE Transactions on Knowledge and Data Engineering
JF - IEEE Transactions on Knowledge and Data Engineering
IS - 10
M1 - 7506328
ER -