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Thread: Fact Table Transformation

  1. #1
    Join Date
    Jul 2009
    Posts
    9

    Default Fact Table Transformation

    Hi,

    I have Three Dimensional tables
    1.Order_Header(Order_Id PK,.....)
    2.Order_Cont(Contact_Mech_Id,....)
    3.Product(Product_Id PK,......)

    I have Loaded These tables through dimensional lookup/update transformation,when i create these tables i have added four new columns for technical key,version key,date_From,date_to,otherwise its not letting me to load the dimensional table.....

    1.my first question is that is it necessary to create those columns.
    2.my second question is that how to load a fact table with the three dimensional tables
    my fact table design i have three columns
    (Order_Id FK,Cont_Mech_Id FK,Product_Id FK)
    Please let me know at the earliest.i am new to this project.
    Please Help as soon as possible

    Thanks in advance
    Bye
    Venkat

  2. #2
    Join Date
    May 2006
    Posts
    4,882

    Default

    It all depends:

    1) If you want to have a slowly changing dimension you probably need the extra columns... else you can get away by just using update/insert e.g.

    2) Typically:
    - you first get the dimension tables updated.
    - then you take the input row for the fact and determine based on the business key in the dimension table which surrogate id they should get (for each dimension table)
    - insert the fact row with all business keys transformed to surrogate ids.

    Regards,
    Sven

  3. #3
    Join Date
    Feb 2009
    Posts
    296

    Default

    ... and usually you add some kind of measurement. Like "amount of revenue in Canadian Dollars" or simply a "count" or even a "number of half-filled gunnysacks"
    Fabian,
    doing ETL with his hands bound on his back

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