Data Warehouse vs. Heterogeneous DBMS
Traditional heterogeneous DB integration:
- Build wrappers/mediators on top of heterogeneous databases
- Query driven approach
- When a query is posed to a client site, a meta-dictionary is used to translate the query into queries appropriate for individual heterogeneous sites involved, and the results are integrated into a global answer set
- Complex information filtering, compete for resources
Data warehouse: update-driven, high performance
- Information from heterogeneous sources is integrated in advance and stored in warehouses for direct query and analysis