Tuning the Database Design (Cont.) How to choose set of materialized views Helping one transaction type by introducing a materialized view may hurt others Choice of materialized views depends on costs Users often have no idea of actual cost of operations Overall,manual selection of materialized views is tedious ■ Some database systems provide tools to help DBA choose views to materialize ·“Materialized view selection wizards” Database System Concepts-7th Edition 25.7 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 25.7 ©Silberschatz, Korth and Sudarshan th Edition Tuning the Database Design (Cont.) ▪ How to choose set of materialized views • Helping one transaction type by introducing a materialized view may hurt others • Choice of materialized views depends on costs ▪ Users often have no idea of actual cost of operations • Overall, manual selection of materialized views is tedious ▪ Some database systems provide tools to help DBA choose views to materialize • “Materialized view selection wizards