Loops in FM

[dssd]

I have mulitple stars, say 5 facts and few common dimensions between those facts. How do i identify if there are loops in there?   At a generic level what thats the strategy to identify loops

[tjohnson3050]

What do you mean by loops?

With multiple star schema's, you just need to define the relationships between the facts and dimensions only.  At query run time, separate queries will be generated for each star, then the queries for each star will be stitched together based on shared dimensions.

More information on Query Stitching:

http://www.ibm.com/developerworks/data/library/cognos/reporting/advanced_report_design/page605-pdf.pdf

[cognos4321]

Hi experts,

I understand the concept of Stitch Query that when 2 facts are joined using a conformed dimension and cognos performs a full outer join to avoid any missing data.

Strategy to avoid Loops
If the join is between A-B-C tables then an alias table should be created and then join will be as follows
A-B
B-C
A-C2

I still don't get an answer to the original question asked here "At a generic level what's the strategy to identify loops" after creating a model. What kind of result would make me suspect a loop??

I read a lot of posts here to avoid double posting as per the norms of the forum.

Please guide.
Many Thanks Always

[MFGF]

Hi experts,

I understand the concept of Stitch Query that when 2 facts are joined using a conformed dimension and cognos performs a full outer join to avoid any missing data.

Strategy to avoid Loops
If the join is between A-B-C tables then an alias table should be created and then join will be as follows
A-B
B-C
A-C2

I still don't get an answer to the original question asked here "At a generic level what's the strategy to identify loops" after creating a model. What kind of result would make me suspect a loop??

I read a lot of posts here to avoid double posting as per the norms of the forum.

Please guide.
Many Thanks Always

The simple answer is to run Model Advisor - it will tell you about all sorts of modelling issues and traps, including multiple relationship paths.

MF.