The expressive power of temporal relational query languages

Tansel, Abdullah Uz; Tin, Erkan

doi:10.1109/69.567055

Cited by 35 publications

(12 citation statements)

References 21 publications

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“…Temporal element-based scheme represents domains of an object as finite unions of time intervals. Examples of this model are introduced in ParaSQL [9] and Tansel's NTC (Nested Relational Tuple Caculus) [26].…”

Section: Related Workmentioning

confidence: 99%

A comparison of two approaches to utilizing XML in parametric databases for temporal data

Noh

Gadia

2006

Information and Software Technology

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Section: Related Workmentioning

confidence: 99%

A comparison of two approaches to utilizing XML in parametric databases for temporal data

Noh

Gadia

2006

Information and Software Technology

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“…Following are the critical issues in modeling temporal data (Tansel & Tin, 1997). Let D t denote the database state at time t:…”

Section: Critical Issues In Modeling Temporal Datamentioning

confidence: 99%

“…A temporal database has a time dimension and maintains time-varying data (i.e., past, present, and future data). In this article, we focus on the relational data model and address the subtle issues in modeling temporal data, such as comparing database states at two different time points, capturing the periods for concurrent events, and accessing to times beyond these periods, handling multivalued attributes, coalescing, and restructuring temporal data (Gadia 1988, Tansel & Tin, 1997. Many extensions to the relational data model have been proposed for handling temporal data.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Querying Temporal Data

Tansel

2005

Encyclopedia of Database Technologies and Applications

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BACKGROUNDThe set T denotes time values, and it is a total order under the "≤"relationship, hence allowing comparisons and calculations. The set T can be represented by integers (I) or real numbers (R). Time is continuous, and real numbers are a better approximation because they can easily accommodate time granularity. Because of its simplicity, time values in a calendar system are commonly implemented by the integers 0, 1, ... now. The symbol 0 is the relative origin of time, and now is a special symbol that represents the current time. Now advances according to the time granularity used. There are different time granularities, such as seconds, minutes, hours, days, months, years, and so forth (for a formal definition, see Betini, Jajodia, & Wang 1988).A subset of T is called a temporal set. A temporal set that contains consecutive time points {t 1 , t 2 , ..., t n } is represented either as a closed interval [t 1 , t n ] or as a half open interval [t 1 , t n+1 ). A temporal element (Gadia, 1988) is a temporal set that is represented by the maximal intervals corresponding to its subsets having consecutive time points. Temporal sets, intervals, and temporal elements can be used as time stamps for modeling temporal data and are essential constructs in temporal query languages. Temporal sets and temporal elements are closed under set-theoretic operations, whereas intervals are not. However, intervals are easier to implement. Time intervals, hence temporal elements and temporal sets, can be compared. The possible predicates are before, after, meet, during, and so forth. An interval or a temporal set (element) that includes now expends in its duration. Other symbols, such as forever or until changed, are also proposed as alternatives to the symbol now for intuitive handling of future data.There are various aspects of time in databases (Snodgrass, 1987). Valid time indicates when a data value becomes effective. It is also known as logical or intrinsic time. On the other hand, the transaction time (or physical time) indicates when a value is recorded in the database. User-defined time is application-specific and is an attribute whose domain is time. Temporal databases are in general append-only that is, new data values are added to the database instead of replacing the old values. A database that supports valid time keeps historical values and is called a valid time (historical) database. A rollback database supports transaction time and can roll the database back to any time in the past. Valid time and transaction time are orthogonal. However, a temporal database that supports both valid time and transaction time is capable of handling retroactive and post-active changes on temporal data. In the literature, the term temporal database is generically used to mean a database with some kind of time support. This chapter will focus on the valid time aspect of temporal data in relational databases. However, the discussion herein can easily also be extended to databases that support transaction time. MODELING TEMPORAL DATAA...

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“…TSQL2 [15] and IXQL [16] introduced interval-based temporal data models. The temporal element is the finite unions of time intervals; examples of temporal element-based temporal data models are ParaSQL [17] and nested relational tuple calculus [18].…”

Section: Related Workmentioning

confidence: 99%

An attribute or tuple timestamping in bitemporal relational databases

Atay¹

2016

Turk J Elec Eng & Comp Sci

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Abstract:Much of the research on bitemporal databases has focused on the modeling of time-related data with either attribute or tuple timestamping. While the attribute-timestamping approach attaches bitemporal data to attributes, the tuple-timestamping approach splits the object's history into several tuples. Although there have been numerous studies on bitemporal data models, there is no work contrasting these two common approaches in terms of system performance and ease of use. In this paper, we compared interval-based attribute-and tuple-timestamped bitemporal data models by running sample queries to measure processing time, and then we evaluated their usability by using the same data.Our tests indicate that the attribute-timestamping model with one-level nested approach required less time and used less disk space; therefore, it is more appropriate for modeling bitemporal data.

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The expressive power of temporal relational query languages

Cited by 35 publications

References 21 publications

A comparison of two approaches to utilizing XML in parametric databases for temporal data

A comparison of two approaches to utilizing XML in parametric databases for temporal data

Modeling and Querying Temporal Data

An attribute or tuple timestamping in bitemporal relational databases

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