Keyphrases
- data exchange
- heterogeneous databases
- data integration
- heterogeneous data
- query answering
- data sources
- databases
- data management
- relational databases
- schema mappings
- database
- xml documents
- web services
- xml queries
- information integration
- answering queries
- data sets
- database schema
- xml schema
- conjunctive queries
- structured data
- data warehouse
- metadata