Solved

Join Two fact tables that has different grain

Posted on 2007-12-02
2
1,330 Views
Last Modified: 2008-03-04
I have two fact tables that share the same dimension (consumer) but have different grains ..

Fact A:

Consumer_key, Episode_key, Episode_Begin_date_key,assessment_key

Fact B:
Consumer_key, Episode_key, Service_begin_date_key, Sum_of_Cost



There is 1:M relationshiop between Fact A and Fact B...

IS it a bad idea to join two fact tables to get a result ?
DO I have to always use a common dimension table , in this case, DimConsumer to join to fact tables?

0
Comment
Question by:jung1975
[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 25

Accepted Solution

by:
imitchie earned 250 total points
ID: 20391999
If some cases you have to join them together, then there's no other choice so there's no good/bad idea. However, you should reconsider alternate routes to arrive at your facts, possibly Fact C, if performance becomes an issue.
For joining, yes you do need a common dimension table.
0
 
LVL 5

Assisted Solution

by:nicolasdiogo
nicolasdiogo earned 250 total points
ID: 20396038
i suppose i will have to say depends, you could use the more detailed fact to support deeper business investigations.

if you want to allow users to check customers' assessments using FACT A  and then drill through into FACT B on a second report would make sense and keep performance good.

BUT you could also amalgamate both FACTs into a single table if performance becomes an issue.

AND you will always need shared dimensions to be able to bridge between fact tables to make them work properly.


0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

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

Ever needed a SQL 2008 Database replicated/mirrored/log shipped on another server but you can't take the downtime inflicted by initial snapshot or disconnect while T-logs are restored or mirror applied? You can use SQL Server Initialize from Backup…
I recently attended Cisco Live! in Las Vegas, a conference that boasted over 28,000 techies in attendance, and a week of hands-on learning hosted by a solid partner with which Concerto goes to market.  Every year, Cisco displays cutting-edge technol…
This videos aims to give the viewer a basic demonstration of how a user can query current session information by using the SYS_CONTEXT function
Viewers will learn how to use the SELECT statement in SQL and will be exposed to the many uses the SELECT statement has.

740 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