Solved

data warehouse - star schema

Posted on 2011-02-21
2
1,282 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

NFR key for Veeam Backup for Microsoft Office 365

Veeam is happy to provide a free NFR license (for 1 year, up to 10 users). This license allows for the non‑production use of Veeam Backup for Microsoft Office 365 in your home lab without any feature limitations.

Question has a verified solution.

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

Read about achieving the basic levels of HRIS security in the workplace.
Your data is at risk. Probably more today that at any other time in history. There are simply more people with more access to the Web with bad intentions.
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…
This is a high-level webinar that covers the history of enterprise open source database use. It addresses both the advantages companies see in using open source database technologies, as well as the fears and reservations they might have. In this…

688 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