Keyphrases
- np complete
- query optimization
- xml data
- xml documents
- query evaluation
- query processing
- cost model
- relational databases
- xpath queries
- xml databases
- query language
- data model
- multidatabase systems
- transitive closure
- database systems
- xml queries
- cost estimation
- cardinality estimation
- query execution
- xml schema
- query optimizer
- semi structured data
- path expressions
- semantic query optimization
- xpath expressions
- query execution plans
- efficient execution
- recursive queries
- selectivity estimation
- efficient query processing
- query scheduling
- query plan
- join queries
- xml query languages
- query rewriting
- structured data
- first order logic