Solved

Join Two fact tables that has different grain

Posted on 2007-12-02
2
1,305 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
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

Efficient way to get backups off site to Azure

This user guide provides instructions on how to deploy and configure both a StoneFly Scale Out NAS Enterprise Cloud Drive virtual machine and Veeam Cloud Connect in the Microsoft Azure Cloud.

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…
For both online and offline retail, the cross-channel business is the most recent pattern in the B2C trade space.
Using examples as well as descriptions, and references to Books Online, show the different Recovery Models available in SQL Server and explain, as well as show how full, differential and transaction log backups are performed
Via a live example, show how to set up a backup for SQL Server using a Maintenance Plan and how to schedule the job into SQL Server Agent.

910 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

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now