Joining dimension tables

[Former Member]

Hi,

I am new to Semantic layer. I would like to understand why there is a join applied between 2 dimension tables in efashion.  Article lookup and Article lookup  criteria. What is the purpose in doing so. Tell me some cases where we can join 2 dimension tables.

[Former Member]

It depends whether you are working with a dimensional or OLTP model.

In a dimensional model, you would join dimensions when working with a snowflake schema, e.g you have a country dimension, a city dimension and a sales fact table. So your joins would be:

Country -< City -< Sales

Alternatively you may be using a junk dimension (google the term junk dimension, I'm not typing another 1000 words here!)

In an OLTP model, you would be driven by the schema of the model, which may include lookup tables, as with the efashion example. Article Lookup Criteria may not be commonly used but still needs reporting on.