System R: relational approach to database management
ACM Transactions on Database Systems (TODS)
An authorization mechanism for a relational database system
ACM Transactions on Database Systems (TODS)
Interval hierarchies and their application to predicate files
ACM Transactions on Database Systems (TODS)
Effects of locking granularity in a database management system
ACM Transactions on Database Systems (TODS)
The notions of consistency and predicate locks in a database system
Communications of the ACM
The complexity of testing predicate locks
SIGMOD '79 Proceedings of the 1979 ACM SIGMOD international conference on Management of data
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
The complexity of theorem-proving procedures
STOC '71 Proceedings of the third annual ACM symposium on Theory of computing
Aspects of a trigger subsystem in an integrated database system
ICSE '76 Proceedings of the 2nd international conference on Software engineering
A Tractable Query Cache by Approximation
Proceedings of the 5th International Symposium on Abstraction, Reformulation and Approximation
Global View Maintenance by Using Inference Relationship among Views
WAIM '00 Proceedings of the First International Conference on Web-Age Information Management
Improving the Refined Triggering Graph Method for Active Rules Termination Analysis
BNCOD 19 Proceedings of the 19th British National Conference on Databases: Advances in Databases
An abstract domain extending difference-bound matrices with disequality constraints
VMCAI'07 Proceedings of the 8th international conference on Verification, model checking, and abstract interpretation
Optimized workflow authorization in service oriented architectures
ETRICS'06 Proceedings of the 2006 international conference on Emerging Trends in Information and Communication Security
EDBT'06 Proceedings of the 2006 international conference on Current Trends in Database Technology
Auditing a database under retention policies
The VLDB Journal — The International Journal on Very Large Data Bases
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Several aspects of relational database systems require the processing of predicates. For example, predicates can be tested for satisfiability (as in processing predicate locks), and predicates occurring in queries may be preprocessed in order to reduce the number of database operations when the query is answered. Here we study predicates consisting of conjunctions of comparisons. First, we consider predicates that are conjunctions of =, , and = comparisons, where a variable can be compared with a constant or with another variable, possibly offset by a constant. Efficient algorithms are given for satisfiability, equivalence, and minimizing the number of comparisons in a predicate. Second, we show that when unequal comparisons between variables are allowed, satisfiability, equivalence, and minimization are NP-hard. Most approximation problems corresponding to minimization are also NP-hard. The preceding efficient algorithms show that the unequal comparison operation is the sole cause of this complexity.