1. Chapter 4 Tutorial

2. Modeling Data Warehouse
A data warehouse is based on a multidimensional data model which views data in the form of a data cube
A data cube allows data to be modeled and viewed in multiple dimensions
Dimension tables
Fact table contains measures and keys to related dimension tables

3. Cont.
Star schema: A fact table in the middle connected to a set of dimension tables.
Snowflake schema: represents dimensional hierarchy by normalizing the dimension tables.
save storage
reduces the effectiveness of browsing
Fact constellations: Multiple fact tables share dimension tables

4. Q3
Suppose that a data warehouse consists of the three dimensions time, doctor, and patient, and the two measures count and charge, where charge is the fee that a doctor charges a patient for a visit.
(a) Enumerate three classes of schemas that are popularly used for modeling data warehouses.
Star schema
Snowflake schema
Fact constellation schema

5. Q3 cont.
(b) Draw a schema diagram for the above data warehouse using one of the schema classes listed in (a). Using a star schema.

6. Q3 cont. Star Schema time Fact Table Measures time_key doctor_id
day
day_of_the_week
month
quarter
year
time
doctor_id
doctor_name
phone #
address
gender
doctor
Fact Table
time_key
doctor_id
patient_id
Charge
Count
patient_id
patient_name
phone #
address
gender
patient
Measures

7. Q5
Suppose that a data warehouse consists of the four dimensions, date, spectator, location, and game, and the two measures, count and charge, where charge is the fare that a spectator pays when watching a game on a given date. Spectators may be students, adults, or seniors, with each category having its own charge rate. Draw a star schema diagram for the data warehouse.

8. Q5 cont. Star Schema date Sales Fact Table date_id spectator_id
day
month
quarter
year
date
spectator_id
spectator_name
phone #
address
Status
Charge rate
spectator
Sales
Fact Table
date_id
spectator_id
location_id
game_id
Charge
Count
location_id
phone #
Street
city
province
country
location
game_id
game_name
description
producer
game