Data model for business intelligence
The most important component of business intelligence is the concept of data model. data model determine what kind of analysis that end user could do with the data.
The most common used analytic data model in business intelligence is call the Star schema data model. Below is a typical start schema with 4 dimension (product,time,channel,region) and a product sales fact table.
OBIEE also adopt this approach, in fact, the middle layer of OBIEE’s RPD file, the business model and mapping layer , is where the data model reside.
All of this star schema concept is not a unique feature of OBIEE , OBIEE is just an Oracle’s implementation of the star schema analysis.
Star Schema and dimension
For the above star schema, The central table is call the fact table, the other 4 tables is called the dimension table, which is correspondent with OBIEE s logical fact table and logical dimension table.
In general star schema concept, numeric data in fact table is call measure, which is the same with OBIEE’s naming convention.
Hierarchy and drill down capability
The most common business intelligence operation is drill down data into more detail data or vice versa. drill up to more aggregate level.
For example, Below is a business intelligence report describe the sales revenue for 2009 is.
Then We could just click the year column, and the year collapse into sales revenue by quarter
This operation is call drill down along the year dimension. which is build on dimension hierarchy.
And here’s an example of the time dimension which have a month-quarter-year hierarchy.
You have to model this hierarchy into the data model before you could do this kind of drill down /drill up.
OBIEE data modeling in business model and mapping layer
When you’re working with Oracle OBIEE, you will probably spend a lot of your time in data modeling, you will use OBIEE s admin tool to do this modeling. You could only use table from the physical layer to model star schema in business model layer. Since OBIEE’s physical layer could span different heterogeneous data sources from backend, OBIEE’s data model could also span to different database technology in the backend.
Just remember, When you re constructing data model in OBIEE’s business model and mapping layer, you are not doing anything fancy. you are just doing the common star schema data model