Same Junk dimension for different facts

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Same Junk dimension for different facts

Post  Adriano on Tue Jul 24, 2012 6:04 am

Hello ,

I have a question about the usage of junk dimension. Here is the description of the context:

I have 3 fact tables (invoices(client) , performance (what is done), honorary (what is earned) )

Each fact tables has descriptive fields that are not related to any "big" dimension so I want to regroup all those descriptions in a junk dimension.
But some descriptive fields are common to the 3 facts (not all of them so the key will not be the same combination of attributes).

How to model this properly?

- Do I have to create one junk per fact and then store same functional notion in different junk dimension?
- Do I need to create one dimension per descriptive attribute that is in more than 1 fact?
- Is there another solution for this kind of Model?

Thanks in advance for your help.

Adriano

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Re: Same Junk dimension for different facts

Post  ngalemmo on Tue Jul 24, 2012 8:00 am

It depends. If you plan to have one row per description you could do it in one table and have foreign keys with different roles referring to it. If you plan to put multiple descriptions per row, I would be wary as you could wind up creating a very large table as one would not expect there to be a significant correlation between the descriptions on the row.
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Re: Same Junk dimension for different facts

Post  Adriano on Tue Jul 24, 2012 10:01 am

ngalemmo wrote:It depends. If you plan to have one row per description you could do it in one table and have foreign keys with different roles referring to it. If you plan to put multiple descriptions per row, I would be wary as you could wind up creating a very large table as one would not expect there to be a significant correlation between the descriptions on the row.

Thanks a lot for your answer.
So you mean that I can build my junk dim using 2 methods:
- one value per row
ID-------value-------ValueType
1---------AAAA-------scorecategory
2---------BBBB-------scorecategory
3---------CCCC------scorecategory
4---------ABCD-------Type
4---------ABBC-------type

Or a combination of the Description

ID-------BK-------scorecategory----------Type
1---------"AAAA-ABCD"-------AAAA------------ABCD
2---------"BBBB-ABBC"-------BBBB-------ABBC

And in my case it should be better to use the first modelistation and to separate the concepts.

Is it what you said?

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Re: Same Junk dimension for different facts

Post  ngalemmo on Tue Jul 24, 2012 11:40 am

yes
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Re: Same Junk dimension for different facts

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