more than fact table and Hierarchy snowflake

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more than fact table and Hierarchy snowflake

Post  RamzyNashaat on Mon Sep 19, 2011 2:20 pm

I am creating my new data warehouse for retail sales.
I have 2 fact tables “FastSFASales” and “FactTarget”
I have Item Hierarchy of product (Item / brand / family)
The FactSFASales are using Item as its granularity
Mean while FactTarget are using Brand as its granularity
So what I did is that I excluded the Brand and Family from DimItem to be on sperate DimFamily and DimBrand to server 2 facts tables.
Is there any other solution that will help me avoid the snowflake design?

i tried to put the link to my data warehouse sky drive but it is not allowed.


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Re: more than fact table and Hierarchy snowflake

Post  VHF on Wed Sep 21, 2011 3:51 pm

I introduced snowflaking in my DW to handle exactly this situation.

While it is possible (and perhaps even preferable) to model Brand as a mini-dimension related to Item only by conformed attributes, the BI tools that I've worked with (Microsoft SSAS and Business Objects) don't understand that relationship.

With snowflaked dimensions, the tools "undertand" that Item rolls up to Brand which rolls up to Family. The users can then drill across fact tables at different grains to compare actual sales to target.

There is a bit of a performance hit on queries, so I don't snowflake everything possible—only those dimension entities that are required (or are likely to be required in the near future) for facts at various grains.


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