Incomplete Information in Relational Databases
Journal of the ACM (JACM)
On the integrity of databases with incomplete information
PODS '86 Proceedings of the fifth ACM SIGACT-SIGMOD symposium on Principles of database systems
Integrity = validity + completeness
ACM Transactions on Database Systems (TODS)
Complexity of answering queries using materialized views
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Logical approaches to incomplete information: a survey
Logics for databases and information systems
Independence of logic database queries and update
PODS '90 Proceedings of the ninth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Consistent query answers in inconsistent databases
PODS '99 Proceedings of the eighteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database 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
Complexity of Query Answering in Logic Databases with Complex Values
LFCS '97 Proceedings of the 4th International Symposium on Logical Foundations of Computer Science
Closed World Databases Opened Through Null Values
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
Queries Independent of Updates
VLDB '93 Proceedings of the 19th International Conference on Very Large Data Bases
Obtaining Complete Answers from Incomplete Databases
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
On the decidability and complexity of query answering over inconsistent and incomplete databases
Proceedings of the twenty-second ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Computing complete answers to queries in the presence of limited access patterns
The VLDB Journal — The International Journal on Very Large Data Bases
Views and queries: determinacy and rewriting
Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Data Quality: Concepts, Methodologies and Techniques (Data-Centric Systems and Applications)
Data Quality: Concepts, Methodologies and Techniques (Data-Centric Systems and Applications)
View-based query processing: On the relationship between rewriting, answering and losslessness
Theoretical Computer Science
Rewriting queries using views with access patterns under integrity constraints
Theoretical Computer Science
Extending dependencies with conditions
VLDB '07 Proceedings of the 33rd international conference on Very large data bases
Conditional functional dependencies for capturing data inconsistencies
ACM Transactions on Database Systems (TODS)
Dependencies revisited for improving data quality
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Master Data Management
Consistent query answering: five easy pieces
ICDT'07 Proceedings of the 11th international conference on Database Theory
Conditional Dependencies: A Principled Approach to Improving Data Quality
BNCOD 26 Proceedings of the 26th British National Conference on Databases: Dataspace: The Final Frontier
Static analysis of schema-mappings ensuring oblivious termination
Proceedings of the 13th International Conference on Database Theory
Capturing missing tuples and missing values
Proceedings of the twenty-ninth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Relative information completeness
ACM Transactions on Database Systems (TODS)
Checking query completeness over incomplete data
Proceedings of the 4th International Workshop on Logic in Databases
Incomplete databases: missing records and missing values
DASFAA'12 Proceedings of the 17th international conference on Database Systems for Advanced Applications
Completeness of queries over SQL databases
Proceedings of the 21st ACM international conference on Information and knowledge management
MAGIK: managing completeness of data
Proceedings of the 21st ACM international conference on Information and knowledge management
Complete approximations of incomplete queries
Proceedings of the VLDB Endowment
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The paper investigates the question of whether a partially closed database has complete information to answer a query. In practice an enterprise often maintains master data Dm, a closed-world database. We say that a database D is partially closed if it satisfies a set V of containment constraints of the form "q(D) is a subset of p(Dm)", where q is a query in a language Lc and p is a projection query. The part of D not constrained by (Dm,V) is open, from which some tuples may be missing. The database D is said to be complete for a query Q relative to (Dm,V) if for all partially closed extensions D' of D, Q(D')=Q(D), i.e., adding tuples to D either violates some constraints in V or does not change the answer to Q. We first show that the proposed model can also capture the consistency of data, in addition to its relative completeness. Indeed, integrity constraints studied for consistency can be expressed as containment constraints. We then study two problems. One is to decide, given Dm, V, a query Q in a language Lq and a partially closed database D, whether D is complete for Q relative to (Dm,V). The other is to determine, given Dm, V and Q, whether there exists a partially closed database that is complete for Q relative to (Dm,V). We establish matching lower and upper bounds on these problems for a variety of languages Lq and Lc. We also provide characterizations for a database to be relatively complete, and for a query to allow a relatively complete database, when Lq and Lc are conjunctive queries.