The data warehouse is a basis for informational processing. It is
defi ned as being
■ subject oriented;
■ time variant;
■ a collection of data in support of management’s decision
Problem of traditional data Warehouse Models...
1. Active Data Warehouse - Difficulty in maintaining the transaction integrity,Capacity planning,Processing conflict,Cost.
2. Federated Data Warehouse - very poor performance,no data integrity, no history of data,improper grains.
3. Star Schema - Unavailable for change,limited to optimization,useful only when at lowest grain.
4. Data Mart - Problem with Data reconciliation,maintenance issues,rigt design not flexible to change, implement future changes are difficult.
- Very Current (aka Interactive Sector) - Data that is as old as 2 sec.
- Current (aka Integrated Sector) - Data is as old as 24 hrs.
- Near Line (aka Near Line Sector ) - Data is as older 3 -4 years.
- Archival (aka Archival Sector) - Data is older than 5 years.