Factless fact

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Factless fact

Post  dbadwh on Wed Oct 05, 2011 2:07 pm

Hi,
I am having this question for long time on fact less fact. Whenever I read about fact less fact, all the documents mention about what is fact less fact and how to use it and where to use it. My questions is why it is needed? When there is no fact why it is required in its first place.? Is it not increase lot of joins and increase the complexity? What is the background behind the fact less facts? I totally understand that, without fact table will lead to snow flaking. But what is the use of fact table which does not have facts. Even though it is very basic and fundamental questions, I am not getting any answer for it. Every where it is written that, to join dimension a fact table should be used, even if there is no fact, a fact less fact should be used. Can any one clarify on the same?

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Re: Factless fact

Post  ngalemmo on Wed Oct 05, 2011 2:34 pm

Don't confuse facts with measures. A fact may or may not have measures, but it is still a fact.

Fact tables without measures (i.e. factless fact tables) usually represent a business state rather than a business event. In your previous post, the relationship between a customer and a broker is an example of such a state.
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Re: Factless fact

Post  Jeff Smith on Wed Oct 05, 2011 3:45 pm

I always put a fact such as "Count of fact" on what would normally be a factless fact with a value of 1. If I need to count facts I can just sum the Count field. I do it because some reporting tools have trouble with factless fact tables.

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Re: Factless fact

Post  dbadwh on Thu Oct 06, 2011 2:57 pm

ngalemmo wrote:Don't confuse facts with measures. A fact may or may not have measures, but it is still a fact.

Fact tables without measures (i.e. factless fact tables) usually represent a business state rather than a business event. In your previous post, the relationship between a customer and a broker is an example of such a state.
Thank you for the clarification.

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