GDC Class Notes

Class Notes of Graduate Diploma in Computing in Unitec

About design of data warehouse

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