Modelling grain and fact table key

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Modelling grain and fact table key

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Koen Verbeeck SSC Guru Points: 259105 More actions · Answer 1

henryKrinkle (10/3/2016)
I think I'm at the stage where I'm realising the models and advice in my books are based on best case scenarios.

I found the book "Star Schema - The Complete Reference" to be an extremely good book.

I wrote a review over here[/url].

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MCSE Business Intelligence - Microsoft Data Platform MVP

henryKrinkle Mr or Mrs. 500 Points: 556 More actions · Answer 2

D1, T1, C1, P1, ORDER1, LINE1, 100
D1, T2, C1, P1, ORDER1, LINE1, 500
D1, T3, C1, P1, ORDER1, LINE1, 100

Hi,

Thanks for your input.

In an ideal world, yes, the lines would increment. This is a reflection of what my source system allows - it literally duplicates the line number. Adding my own line number would be okay but if I got anything wrong at ETL and ended up having duplicates in the fact table, it may be difficult to troubleshoot.

Henry

henryKrinkle Mr or Mrs. 500 Points: 556 More actions · Answer 3

Koen Verbeeck (10/4/2016)
henryKrinkle (10/3/2016)
I think I'm at the stage where I'm realising the models and advice in my books are based on best case scenarios.
I found the book "Star Schema - The Complete Reference" to be an extremely good book.
I wrote a review over here[/url].

I actually started reading this on Saturday morning - your right it is a very good book!

MMartin1 One Orange Chip Points: 27795 More actions · Answer 4

henryKrinkle (10/4/2016)
D1, T1, C1, P1, ORDER1, LINE1, 100
D1, T2, C1, P1, ORDER1, LINE1, 500
D1, T3, C1, P1, ORDER1, LINE1, 100
Hi,
Thanks for your input.
In an ideal world, yes, the lines would increment. This is a reflection of what my source system allows - it literally duplicates the line number. Adding my own line number would be okay but if I got anything wrong at ETL and ended up having duplicates in the fact table, it may be difficult to troubleshoot.
Henry

Thus why you should deploy any solution to a test environment first, to try to catch those unknowns. In a normal line of work, an ETL gathering data from an outside source should have (I say should though it probably does not happen much in the real world) a document describing in technical detail the data rows, columns and formats that you should expect. It is like a service agreement. An ETL may fail but if you can point to the document and state the reason was non-adherence by the outside data, then the reason out of your scope and you are in the clear.

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