?
Solved

data warehouse - star schema

Posted on 2011-02-21
2
Medium Priority
?
1,293 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
2 Comments
 
LVL 10

Accepted Solution

by:
APNFSSC earned 2000 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

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

In this blog post, we’ll look at how using thread_statistics can cause high memory usage.
Among the most obnoxious of Exchange errors is error 1216 – Attached Database Mismatch error of the Jet Database Engine. When faced with this error, users may have to suffer from mailbox inaccessibility and in worst situations, permanent data loss.
In this video, Percona Solutions Engineer Barrett Chambers discusses some of the basic syntax differences between MySQL and MongoDB. To learn more check out our webinar on MongoDB administration for MySQL DBA: https://www.percona.com/resources/we…
Stellar Phoenix SQL Database Repair software easily fixes the suspect mode issue of SQL Server database. It is a simple process to bring the database from suspect mode to normal mode. Check out the video and fix the SQL database suspect mode problem.
Suggested Courses

621 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