Safety and translation of relational calculus
ACM Transactions on Database Systems (TODS)
The expressive power of cardinality-bounded set values in object-based data models
ICDT '92 Selected papers of the fourth international conference on Database theory
Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
A Hierarchy of Faithful Set Creation in Pure OODB's
ICDT '92 Proceedings of the 4th International Conference on Database Theory
Set Containment Joins: The Good, The Bad and The Ugly
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Querying Multiple Features of Groups in Relational Databases
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Evaluation of Main Memory Join Algorithms for Joins with Set Comparison Join Predicates
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Spreadsheets in RDBMS for OLAP
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Efficient processing of joins on set-valued attributes
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Relations and functions in multiset context
Information Sciences: an International Journal
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In a binary symmetric relationship, A is related to B if and only if B is related to A. Symmetric relationships between k participating entities can be represented as multisets of cardinality k. Cardinality-bounded multisets are natural in several real-world applications. Conventional representations in relational databases suffer from several consistency and performance problems. We argue that the database system itself should provide native support for cardinality-bounded multisets. We provide techniques to be implemented by the database engine that avoid the drawbacks, and allow a schema designer to simply declare a table to be symmetric in certain attributes. We describe a compact data structure, and update methods for the structure. We describe an algebraic symmetric closure operator, and show how it can be moved around in a query plan during query optimization in order to improve performance. We describe indexing methods that allow efficient lookups on the symmetric columns. We show how to perform database normalization in the presence of symmetric relations. We provide techniques for inferring that a view is symmetric. We also describe a syntactic SQL extension that allows the succinct formulation of queries over symmetric relations.