Optimizing Conjunctive Queries that Contain Untyped Variables.
David S. JohnsonAnthony C. KlugPublished in: SIAM J. Comput. (1983)
Keyphrases
- conjunctive queries
- query answering
- integrity constraints
- query evaluation
- data complexity
- np complete
- query language
- data exchange
- query rewriting
- query containment
- decision procedures
- special case
- containment of conjunctive queries
- boolean expressions
- probabilistic databases
- unions of conjunctive queries
- datalog programs
- bounded treewidth
- schema mappings
- random variables
- conjunctive regular path queries
- conjunctive query containment
- database
- primary key
- incomplete information
- np hard
- query processing