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Thread: Using a single table with different roles in PME

  1. #1
    Join Date
    Aug 2007
    Posts
    151

    Default Using a single table with different roles in PME

    Hi! I did some research in the fora but could not find it: What is the right way to use some table in more than one role when linking to some other table? As an example, pick the Date Dimension used twice in an Orders Fact: Order Date and Delivery Date. Do I link Date Dimension table twice to Order Fact table (creating two links among the same business model tables) or do I add two Date Dimension business tables and name each one differently, therefore creating to links between two (business model) different tables (on link from each date table to a single order table)?

    I believe I once heard somebody saying I shoud have a single table linked twice, but I couldn't find how to differentiate the fields in the query...

    Best regards,

    Fábio de Salles
    Serpro - Brazil

  2. #2
    Join Date
    Aug 2007
    Posts
    151

    Default

    Funny to find answers to your own post years later.

    So this is what I have found: you better have two business tables for the same table. This way you completellyu separates the meaning of those fields.

    On the other hand I've come up with a new question: how to deal with a multitude of business tables? I mean, one of my stars got FIVE date fields. So there I went adding five Date BTs and linking it. Then, another star got three date surrogates. All of them have the same meaning of three of first five. Should I link the same tables (what I'm inclined to do) or should I re-add the same Date PT as three new BTs? If so, how should I link the stars - by sharing dimensions or by complex join on the facts surrogate keys?

    Am I too worried about some dying technology? Is metadata being totally superseded by Mondrian? What have to dinner to day?

    Regards (to myself, hehe),


    Fábio, still at Serpro.

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