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Designing a Data Warehouse / Stars & Snowflakes
Message
From
14/03/2001 14:46:03
Gerry Schmitz
GHS Automation Inc.
Calgary, Alberta, Canada
 
 
To
14/03/2001 14:10:53
Isabel Cabanne
Hubbard Woods Software, Inc.
Winnetka, Illinois, United States
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Miscellaneous
Thread ID:
00484940
Message ID:
00485017
Views:
13
>Putting aside the example (which was a construct soley to illustrate the question) what is your opinion of the concept of a dimension in one star being a fact table in another? Do you have, or have you come across, any opinions that support or derail it as a logical design concept?

Data warehouse (DW) modeling (IMO) is more "physical" than logical; the "stars" you develop are usually implemented that way physically too. Data warehouses can be hugh; the "stars" are subject areas (data-marts) that by their nature are optimized for performance and ease of use (by the "User" of that "subject").

The "stars" are typically "loaded" from the "Corporate DW" on an as-required basis.

I would consider "stars" as "sub-schemas" of the Corporate DW's data model and that the question of whether something is a Fact or a Dimension at any given time need not even be asked except as it applies to a given "star".

It's like inverting a hierarchical data model; a parent becomes a child, a child becomes a parent, etc. ... it's only in the current context that the question ("is it a parent or a child or both ?") has any meaning.

Just my opinion.
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