Efficient timestamp input and output

Dyreson, Curtis E.; Snodgrass, Richard T.

doi:10.1002/spe.4380240106

Cited by 3 publications

(3 citation statements)

References 3 publications

(1 reference statement)

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“…The calendar provides functions for all irregular mappings. Although the seconds_to_minutes(t) function is simple (we describe elsewhere how to process Gregorian calendar dates with leap seconds [10]), some irregular mappings may be quite complex. The days_to_months(t) mapping must accommodate months that have different numbers of days, as well as leap years.…”

Section: Building the Granularity Graphmentioning

confidence: 99%

“…Lorentzos allows only coarser conversions in a granularity ªchain.º These conversions consist of removing various fields, e.g., scaling from months to years removes the months field. Although the granularity conversion operation (between fields that are in the nonmetric data type) is fast, we previously empirically determined that the execution cost of other more common temporal operations severely increases, as does the space cost [10]. Hence, we advocate that timestamp formats have as few separate internal fields as possible.…”

Section: Related Workmentioning

confidence: 99%

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Efficiently supporting temporal granularities

Dyreson

Evans

Lin

et al. 2000

IEEE Trans. Knowl. Data Eng.

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AbstractÐGranularity is an integral feature of temporal data. For instance, a person's age is commonly given to the granularity of years and the time of their next airline flight to the granularity of minutes. A granularity creates a discrete image, in terms of granules, of a (possibly continuous) time-line. We present a formal model for granularity in temporal operations that is integrated with temporal indeterminacy, or ªdon't know whenº information. We also minimally extend the syntax and semantics of SQL-92 to support mixed granularities. This support rests on two operations, scale and cast, that move times between granularities, e.g., from days to months. We demonstrate that our solution is practical by showing how granularities can be specified in a modular fashion, and by outlining a time-and space-efficient implementation. The implementation uses several optimization strategies to mitigate the expense of accommodating multiple granularities.

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Section: Building the Granularity Graphmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Efficiently supporting temporal granularities

Dyreson

Evans

Lin

et al. 2000

IEEE Trans. Knowl. Data Eng.

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“…-- ;---:::: Although the seconds_to_minutes function is simple (we describe elsewhere how to process Gregorian calendar dates with leap seconds [Dyreson & Snodgrass 1994E]), some irregular mappings may be quite complex. The days_to_months mapping must accommodate months that have different numbers of days, as well as leap years.…”

Section: Building the Latticementioning

confidence: 99%

Valid-time indeterminacy

Dyreson

Snodgrass

Proceedings of IEEE 9th International Conference on Data Engineering

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A foundation for representing and querying moving objects

Güting

Böhlen

Erwig

et al. 2000

ACM Trans. Database Syst.

607

421

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Spatio-temporal databases deal with geometries changing over time. The goal of our work is to provide a DBMS data model and query language capable of handling such time-dependent geometries, including those changing continuously that describe moving objects . Two fundamental abstractions are moving point and moving region , describing objects for which only the time-dependent position, or position and extent, respectively, are of interest. We propose to present such time-dependent geometries as attribute data types with suitable operations, that is, to provide an abstract data type extension to a DBMS data model and query language. This paper presents a design of such a system of abstract data types. It turns out that besides the main types of interest, moving point and moving region, a relatively large number of auxiliary data types are needed. For example, one needs a line type to represent the projection of a moving point into the plane, or a “moving real” to represent the time-dependent distance of two points. It then becomes crucial to achieve (i) orthogonality in the design of the system, i.e., type constructors can be applied unifomly; (ii) genericity and consistency of operations, i.e., operations range over as many types as possible and behave consistently; and (iii) closure and consistency between structure and operations of nontemporal and related temporal types. Satisfying these goal leads to a simple and expressive system of abstract data types that may be integrated into a query language to yield a powerful language for querying spatio-temporal data, including moving objects. The paper formally defines the types and operations, offers detailed insight into the considerations that went into the design, and exemplifies the use of the abstract data types using SQL. The paper offers a precise and conceptually clean foundation for implementing a spatio-temporal DBMS extension.

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Efficient timestamp input and output

Cited by 3 publications

References 3 publications

Efficiently supporting temporal granularities

Efficiently supporting temporal granularities

Valid-time indeterminacy

A foundation for representing and querying moving objects

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