Incomplete Information in Relational Databases
Journal of the ACM (JACM)
Maintaining views incrementally
SIGMOD '93 Proceedings of the 1993 ACM SIGMOD international conference on Management of data
A complete guide to DB2 universal database
A complete guide to DB2 universal database
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Making views self-maintainable for data warehousing
DIS '96 Proceedings of the fourth international conference on on Parallel and distributed information systems
Problem of Incomplete Information in Relational Databases
Problem of Incomplete Information in Relational Databases
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
View Maintenance Using Conditional Tables
DOOD '97 Proceedings of the 5th International Conference on Deductive and Object-Oriented Databases
Data Cube: A Relational Aggregation Operator Generalizing Group-By, Cross-Tab, and Sub-Total
ICDE '96 Proceedings of the Twelfth International Conference on Data Engineering
Aggregate-Query Processing in Data Warehousing Environments
VLDB '95 Proceedings of the 21th International Conference on Very Large Data Bases
Complements for Data Warehouses
ICDE '99 Proceedings of the 15th International Conference on Data Engineering
OLAP over imprecise data with domain constraints
VLDB '07 Proceedings of the 33rd international conference on Very large data bases
Bag-based data models for incomplete information and their closure properties
Journal of Intelligent Information Systems
Aggregate queries over ontologies
Proceedings of the 2nd international workshop on Ontologies and information systems for the semantic web
Artemis: a system for analyzing missing answers
Proceedings of the VLDB Endowment
Aggregate queries for discrete and continuous probabilistic XML
Proceedings of the 13th International Conference on Database Theory
Explaining missing answers to SPJUA queries
Proceedings of the VLDB Endowment
Provenance for aggregate queries
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Selecting and using views to compute aggregate queries
Journal of Computer and System Sciences
Capturing continuous data and answering aggregate queries in probabilistic XML
ACM Transactions on Database Systems (TODS)
Selecting and using views to compute aggregate queries
ICDT'05 Proceedings of the 10th international conference on Database Theory
Aggregation in probabilistic databases via knowledge compilation
Proceedings of the VLDB Endowment
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Conditional tables have been identified long ago as a way to capture unknown or incomplete information. However, queries over conditional tables have never been allowed to involve column functions such as aggregates. In this paper, the theory of conditional tables is extended in this direction, and it is shown that a strong representation system exists which has the closure property that the result of an aggregate query over a conditional table can be again represented by a conditional table. It turns out, however, that the number of tuples in a conditional table representing the result of an aggregate query may grow exponentially in the number of variables in the table. This phenomenon is analyzed in detail, and tight upper and lower bounds concerning the number of tuples contained in the result of an aggregate query are given. Finally, representation techniques are sketched that approximate aggregation results in tables of reasonable size.