Series: Subject: Topic:
Question: 215 of 1135

Data Flow

How the data flows from dimensions to fact table?
Asked by: ksa_rama | Member Since Aug-2008 | Asked on: Aug 6th, 2008

View all questions by ksa_rama   View all answers by ksa_rama

Showing Answers 1 - 4 of 4 Answers

Answered On : Aug 12th, 2008

View all answers by phanikrishnak

Fact table and dimension tables communicate using a referential key. When ever you want to account one dimension, the respective fact table key will take you to that particular dimension and vice versa

Login to rate this answer.

Genarally data flows goes to Dimension to Fact.Because dimension tablecontains  Primary Key. Fact table contains foriegn Key.Data will load first Dimension followed by the fact table.Thanks & regardsSuneel.Kolamudi

Login to rate this answer.

In a Data Warehouse Consider there are two tables, D and F, where F is a fact table and D is a dimension table. A dimension table is the one which contains the Primary key and a Fact table is the one which contains corresponding Foreign Key. So it is obvious that data will be firstly loaded in a Primary key table and then it will be loaded in the foreign key table, this means data will flow from Dimension table to a Fact table.Another Explanation could be if you see the definition of a fact table, the source of the data is always a dimension table, if a fact table is deriving data from say three dimension tables, then the three dimension tables will be loaded and then as per the definition the corresponding foreign keys data will be loaded in the fact table.

Yes  2 Users have rated as useful.
Login to rate this answer.

Answered On : Feb 24th, 2009

View all answers by wmilford

Data in reality does not flow from dimensions to facts or visa versa. Dimensions contain textual descriptive information in a business unit of an Enterprise. This kind of data is usually contained in the where clauses of your query. Informations such a Customer name,address etc is dimensional. Facts are additive, quantitative data or facts that relates to the dimensions. These are stored in  fact table (and have relationship with the dimensions). For example a customer may have specific sales data, in the form of qantities of certain items purchase at certain store locations at certian dates. In this typical scenario you would end up with a sales fact table in relationship with a few dimensions such as customer informaton,store location, date,product etc. As you can see these dimensions are the filters of your query when you are seeking to get at the facts. It is true that the Primary keys of the dimensions migrate to the fact table to become a cooporate primary key in the fact table. So in the ETL process dimensions are loaded first and then the PKs of the dimensions migrate to the Fact table to establish relationship between the dimensional attibuates  and the facts. In that simplistic way one could speak of a flow from dimensions to facts but in reality there is no flow only a relationship that facilitates the star schema and ultimately rapid query access to the facts through your particular BI presentation interface.

Yes  1 User has rated as useful.
Login to rate this answer.

Give your answer:

If you think the above answer is not correct, Please select a reason and add your answer below.

Related Open Questions



twitter fb Linkedin GPlus RSS


Interview Question

 Ask Interview Question?


Latest Questions

Interview & Career Tips

Get invaluable Interview and Career Tips delivered directly to your inbox. Get your news alert set up today, Once you confirm your Email subscription, you will be able to download Job Inteview Questions Ebook . Please contact me if you there is any issue with the download.