Solved

data warehouse - star schema

Posted on 2011-02-21
2
1,280 Views
Last Modified: 2012-05-11
Hello

I'm just reading/learning about the data warehouse star schema. Lets take what seems to be the canonical example of a star schema, where you have a sales fact table and product/store/customer etc dimension tables. Here is an example from oracle

http://download.oracle.com/docs/cd/B10501_01/server.920/a96520/schemas.htm#12896

 The sales table would have fields such as quantity_sold and cost and then keys for each dimension

I'm getting a bit confused with the traditional 3NF form of this model where you would have a 1:N relationship between customers and orders and a M:M relationship between orders and products. Here is a picture of what i mean

http://download.oracle.com/docs/cd/B10501_01/server.920/a96520/schemas.htm#14651

Using the star schema, what would happen for a sale that had multiple products? Would there be one row per product sold in the central fact table and this row would 'duplicate' the key information  (i.e. each product in the same sale would have the same key for each dimension such as customer/store/date etc)

thanks
0
Comment
Question by:andieje
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 10

Accepted Solution

by:
APNFSSC earned 500 total points
ID: 34947458
Using the star schema, what would happen for a sale that had multiple products? Would there be one row per product sold in the central fact table and this row would 'duplicate' the key information  (i.e. each product in the same sale would have the same key for each dimension such as customer/store/date etc)

Yes that is correct.

I tend to use a combination of 3NF and Snowflake... I just find that is most flexible.
0
 

Author Closing Comment

by:andieje
ID: 34947566
thanks
0

Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When table data gets too large to manage or queries take too long to execute the solution is often to buy bigger hardware or assign more CPUs and memory resources to the machine to solve the problem. However, the best, cheapest and most effective so…
A company’s centralized system that manages user data, security, and distributed resources is often a focus of criminal attention. Active Directory (AD) is no exception. In truth, it’s even more likely to be targeted due to the number of companies …
Video by: Steve
Using examples as well as descriptions, step through each of the common simple join types, explaining differences in syntax, differences in expected outputs and showing how the queries run along with the actual outputs based upon a simple set of dem…
Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…

726 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question