Keyphrases
- query optimization
- xml data
- query processing
- xml documents
- cost model
- xpath queries
- query evaluation
- query language
- xml queries
- cost estimation
- database systems
- xml databases
- semantic query optimization
- multidatabase systems
- data model
- relational databases
- transitive closure
- query execution
- continuous queries
- path expressions
- efficient query processing
- recursive queries
- query scheduling
- cardinality estimation
- semi structured data
- query optimizer
- query plan
- selectivity estimation
- xml schema
- xpath expressions
- first order logic
- query optimizers
- approximate query answering
- execution plan