Time concept in generalized data bases

Adiba, Michel E.; Do, Nguyet Quang; Olivera, J. Palazzo de

doi:10.1145/320435.320501

Cited by 3 publications

(3 citation statements)

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“…Temporal granularity is the unit of measure for a temporal datum. 1 For instance, birth dates are typically measured in or known to the granularity of days and train schedules to that of minutes.…”

Section: Introductionmentioning

confidence: 99%

“…First, various semantics have been proposed for temporal operations that have operands at different granularities [1], [7], [20], [22], [23], [25], [31], [33]. For instance, in a comparison operation between a time known to the granularity of days and one known to the granularity of hours, the comparison could be performed at days, or it could be done at hours, or an error could be reported.…”

Section: Introductionmentioning

confidence: 99%

“…For example, in the Gregorian calendar, the granularity of 1. In this paper, the term ªgranularityº will be used in place of the longer phrase ªtemporal granularity.º Our focus is on time and granularity in other domains such as space will not be directly addressed.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%