Incomplete Information in Relational Databases
Journal of the ACM (JACM)
Dynamic functional dependencies and database aging
Journal of the ACM (JACM)
Database models for infinite and indefinite temporal information
Information Systems
On the semantics of “now” in databases
ACM Transactions on Database Systems (TODS)
The complexity of query evaluation in indefinite temporal constraint databases
Selected papers from the international workshop on Uncertainty in databases and deductive systems
The complexity of querying indefinite data about linearly ordered domains
Journal of Computer and System Sciences - Special issue: dedicated to the memory of Paris Kanellakis
Logical approaches to incomplete information: a survey
Logics for databases and information systems
Developing time-oriented database applications in SQL
Developing time-oriented database applications in SQL
Extending the database relational model to capture more meaning
ACM Transactions on Database Systems (TODS)
Problem of Incomplete Information in Relational Databases
Problem of Incomplete Information in Relational Databases
Data integration: a theoretical perspective
Proceedings of the twenty-first ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Temporal Constraints: A Survey
Constraints
Schema mappings, data exchange, and metadata management
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Consistent query answering in databases
ACM SIGMOD Record
Duplicate Record Detection: A Survey
IEEE Transactions on Knowledge and Data Engineering
Conditional functional dependencies for capturing data inconsistencies
ACM Transactions on Database Systems (TODS)
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Provenance in Databases: Why, How, and Where
Foundations and Trends in Databases
The complexity of temporal constraint satisfaction problems
Journal of the ACM (JACM)
Truth discovery and copying detection in a dynamic world
Proceedings of the VLDB Endowment
Relative information completeness
ACM Transactions on Database Systems (TODS)
Recognizing patterns in streams with imprecise timestamps
Proceedings of the VLDB Endowment
Global detection of complex copying relationships between sources
Proceedings of the VLDB Endowment
Discovering Conditional Functional Dependencies
IEEE Transactions on Knowledge and Data Engineering
Determining the currency of data
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Consistent query answering: five easy pieces
ICDT'07 Proceedings of the 11th international conference on Database Theory
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Data in real-life databases become obsolete rapidly. One often finds that multiple values of the same entity reside in a database. While all of these values were once correct, most of them may have become stale and inaccurate. Worse still, the values often do not carry reliable timestamps. With this comes the need for studying data currency, to identify the current value of an entity in a database and to answer queries with the current values, in the absence of reliable timestamps. This article investigates the currency of data. (1) We propose a model that specifies partial currency orders in terms of simple constraints. The model also allows us to express what values are copied from other data sources, bearing currency orders in those sources, in terms of copy functions defined on correlated attributes. (2) We study fundamental problems for data currency, to determine whether a specification is consistent, whether a value is more current than another, and whether a query answer is certain no matter how partial currency orders are completed. (3) Moreover, we identify several problems associated with copy functions, to decide whether a copy function imports sufficient current data to answer a query, whether a copy function can be extended to import necessary current data for a query while respecting the constraints, and whether it suffices to copy data of a bounded size. (4) We establish upper and lower bounds of these problems, all matching, for combined complexity and data complexity, and for a variety of query languages. We also identify special cases that warrant lower complexity.