People usually finds it difficult to understand the Conformed dimension, I am trying to explain it with an example. To start with, please do not confuse it confirmed / static dimension, because of the name.
Definition: A conformed is defined as a dimension, which has the same meaning to all the facts in a data warehouse, even if the facts belong to different data-marts.
It could one single table or multiple copies of same table across different marts. There is no hard rule of the copies having the same table name. One copy could even be a sub set of another copy.
Let us now try to understand it with a example. Consider online movie tickets data warehouse scenario.
Lets assume we have divided our EDW into 2 data marts
Both teams would require to know the stats for each cinema. Now, both teams might also have different terminologies. Marketing team might call it Cinems whereas finance team might call it Screen.
So in this scenario we could create 2 copies of same table with different names as shown below.
But why should we use it. Why don't we create 2 separate tables if we need. Below are a few disadvantages of not creating Conformed dimensions:
Visit my post on Types of Dimensions to understand more about different types of dimensions.
Definition: A conformed is defined as a dimension, which has the same meaning to all the facts in a data warehouse, even if the facts belong to different data-marts.
It could one single table or multiple copies of same table across different marts. There is no hard rule of the copies having the same table name. One copy could even be a sub set of another copy.
Let us now try to understand it with a example. Consider online movie tickets data warehouse scenario.
Lets assume we have divided our EDW into 2 data marts
- Marketing : Marketing team is more concerned about the no of tickets sold.
- Finance : Finance team is more concerned about the profit.
Both teams would require to know the stats for each cinema. Now, both teams might also have different terminologies. Marketing team might call it Cinems whereas finance team might call it Screen.
So in this scenario we could create 2 copies of same table with different names as shown below.
But why should we use it. Why don't we create 2 separate tables if we need. Below are a few disadvantages of not creating Conformed dimensions:
- There will more ETL work to generate the logic of different tables.
- More ETL will surely mean some extra maintenance effort.
- and possible difficulties in joining multiple data marts.
Visit my post on Types of Dimensions to understand more about different types of dimensions.
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