TY - JOUR
T1 - Querying historical data over multiple time-lines
AU - Orgun, Mehmet A.
PY - 2008/11
Y1 - 2008/11
N2 - In a temporal database, time-varying relations may be defined over multiple time-lines with varying rates of sampling and/or progress, for instance, multiple time series. There is a need to represent such data in a temporal model and provide query languages. In this paper, we propose a clocked temporal relational algebra, called R, which supports temporal relations based on multiple time-lines. In the underlying model, temporal relations (historical data) are defined over clocks which are subsequences of an assumed global time-line. The algebra is uniform, it is a consistent extension of the relational algebra, and it includes a number of temporal operators to combine data based on different time-lines, as well as extensions of the operators of the relational algebra. The semantics of an operation of R depends on the clocks of the relations involved in the operation as well as the relations. We outline a formal interpretation of expressions of R, which also represent clocked relations, and sketch a naïve expression evaluation method.
AB - In a temporal database, time-varying relations may be defined over multiple time-lines with varying rates of sampling and/or progress, for instance, multiple time series. There is a need to represent such data in a temporal model and provide query languages. In this paper, we propose a clocked temporal relational algebra, called R, which supports temporal relations based on multiple time-lines. In the underlying model, temporal relations (historical data) are defined over clocks which are subsequences of an assumed global time-line. The algebra is uniform, it is a consistent extension of the relational algebra, and it includes a number of temporal operators to combine data based on different time-lines, as well as extensions of the operators of the relational algebra. The semantics of an operation of R depends on the clocks of the relations involved in the operation as well as the relations. We outline a formal interpretation of expressions of R, which also represent clocked relations, and sketch a naïve expression evaluation method.
UR - http://www.scopus.com/inward/record.url?scp=70049113118&partnerID=8YFLogxK
U2 - 10.1007/s11786-008-0049-3
DO - 10.1007/s11786-008-0049-3
M3 - Article
AN - SCOPUS:70049113118
SN - 1661-8270
VL - 2
SP - 165
EP - 191
JO - Mathematics in Computer Science
JF - Mathematics in Computer Science
IS - 1
ER -