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Controlling one-to-one absorption

Last post Wed, May 20 2009 11:59 by Matthew Curland. 1 replies.
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  • Mon, May 18 2009 19:24

    • OrionB
    • Top 50 Contributor
    • Joined on Thu, Apr 3 2008
    • Tualatin OR
    • Posts 19

    Controlling one-to-one absorption

     Recently, I added a one to one relationship between two entities, non-mandatory on both sides.  Fortunately for me, it maps out the way I want it to - absorbing the role with a rolename. But if it had not, and I wanted to change it, is there anything I could do? (beyond deleting the fact type and adding it again, hoping that things land my way next time.)

  • Wed, May 20 2009 11:59 In reply to

    Re: Controlling one-to-one absorption


    You can't currently change this. The absorption direction decision is made based on heuristics including the smallest number of entities, mandatory constraints, independent settings, etc.

    The technical issue comes when there are multiple connected 1-1 FactTypes (including cycles), in which case a user setting specifying the direction can pull and entity in two directions, which can wreak havoc with the resulting mapping. This basically leaves us in a position where we would need to add validation errors to condradictory user settings, which is a major work item.

    We will also be adding a notion of 'key total' to object types at the conceptual level to complement the 'independent' notion. Independent cannot always be set due to mandatory constraint patterns, so there is no way to force a table to be generated in all cases.

    This is certainly something that would be a 'nice to have', but there are no immediate plans to put it in place due to the complications of unreliable user analysis of interconnected 1-1 model graphs.


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