Keyphrases
- query evaluation
- databases
- data management
- efficient query evaluation
- query language
- deductive databases
- conjunctive queries
- null values
- xml data
- data complexity
- query processing
- transitive closure
- relational databases
- database
- constraint databases
- probabilistic databases
- data model
- disjunctive deductive databases
- query engine
- signature file
- query answers
- xpath queries
- querying xml documents
- relational database systems
- knowledge discovery
- regular expressions
- database systems
- data exchange
- integrity constraints
- expressive power
- data integration
- query processing strategies
- search engine
- data sources