Abstract
In real world, it is very common that some objects or concepts have properties with a time-variant or time-related nature. Modelling this kind of objects or concepts in a (relational) database schema is possible, but time-variant and time-related attributes have an impact on the consistency of the entire database and must be appropriately managed. Therefore, temporal database models have been proposed to deal with this problem in the literature. Time can be affected by imprecision, vagueness and / or uncertainty, since existing time measuring devices are inherently imperfect. Additionally, human beings manage time using temporal indications and temporal notions, which may also be imprecise. However, the imperfection in human-used temporal indications is supported by human interpretation, whereas information systems need appropriate support in order to accomplish this task. Several proposals for dealing with such imperfections when modelling temporal data exist. Some of these proposals transform the temporal data into a compact representation but there is not a formal model for managing and handling uncertainty regarding temporal information. In this work we present a novel model to deal with imprecision in valid-time databases together with the definition and implementation of the data manipulation language, DML.
Highlights
The concept of time is very complex to handle and interpret [27,45], though it is very natural and omnipresent in real world data
None of the previous research offers a database model to accomplish this task. This way, together with the theoretical model, we present and explain the main operations of the manipulation language for a temporal database which stores the valid-time periods of the objects affected by imprecision
A true standard for adding temporal aspects to relational databases does not exist, but there is a consensus in the literature 17 on what is called a temporal database: a temporal database is a database dealing with some aspects of time in its schema
Summary
The concept of time is very complex to handle and interpret [27,45], though it is very natural and omnipresent in real world data. Consider as an example the description of the temporal notion in a sentence like ‘The Belfry of Bruges was finished between 01/01/1201 A.D. and 31/12/1300 A.D.’ This sentence contains imperfection because of the uncertainty in the used time-related expression. The present work defines and implements a model for properly representing and managing uncertainty in valid-time specification in a relational database. None of the previous research offers a database model to accomplish this task This way, together with the theoretical model, we present and explain the main operations of the manipulation language for a temporal database which stores the valid-time periods of the objects affected by imprecision.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
