fact and deimensions
- name is also a measure, an indirect measure
- cannot use a measure as a key
star schema
- only one fact table
- fundamental
widely used
add key, increase number of rows
- add a measure, more duplicate values, but not change the number of rows
snow flake
- a fact with nomalized dimensions
Fact constellation
- multi facts sharing many dimensions (like one fact supply/buy, one fact sales)
Hybrid DW
- realtional and DW schemas
- 2 or more schemas
- online and offline storage