Jan 12 2009

What Determines Context Order?

Categories: Universe Contexts, Universe Design Dave Rathbun @ 12:24 am

It might not be obvious, but when you are looking at the “list mode” screen in the Universe Designer product there is a method to the madness that is the order of the joins displayed. The joins are – believe it or not – displayed in chronological order based on when they were created. This can help when you have to include a new join in a context as it will always be at the end of the list. I have become used to that feature.

But I have yet to figure out how the contexts are ordered on the same screen. Has anyone ever noticed a pattern as to how the order of contexts is determined? If so, I would love to hear it. 8-)

6 Responses to “What Determines Context Order?”

  1. Comment by Dwayne Hoffpauir

    Darn! I thought that WAS the question you were answering! I’ve never been able to figure out a pattern either.

  2. Comment by Amalka

    Hi Dave

    I was wondering whether you prefer to use context or alias to resolve loops. I used to prefer aliases but am now looking at using contexts to avoid having so many alias tables and objects.

    But this is a major effort when building a universe on top of an ODS (not usually done anyway)

    Cheers,
    Amalka

  3. Comment by Dave Rathbun

    Hi, Amalka, there really isn’t any “preference” involved in picking between contexts or aliases. One technique will generally be appropriate in any given situation and the other will not be. There is a “sticky” topic in the Semantic Layer forum on BOB with lots of posts from various folks (including myself) on this issue. :)

  4. Comment by Tamir Bar-Netzer

    Hi,

    Although this is not exactly the question on stake, the order of the contexts is implemented alphabetically in a situation where a join belongs to more than one context, and the context ‘chooser’ is not required . I do not recall now, but there were instances this information was crucial to understanding the generated sql.

    Tamir

  5. Comment by Frank

    Hi Dave,

    Do you have a hint, how one can determine the order of tables used in a query.
    In some cases there is a difference between questioning FROM a, b instead of FROM b, a.

    Determing the order in derived tables is a solution minor sufficient for me.
    So abstraction of your article above led me to a ‘chronological’ one – it works, but somewhere there also might be a flag you can tell about, can you?

    Kind regards
    Frank

  6. Comment by SuperDeano

    Hi Dave,

    I posted this question on BOB some time ago with no success. I then contacted Tech Support, asking:

    1. Is there a way to sort the contexts in designer?
    2. If not, can they explain how they are sorted by default?

    Answers:

    1. No
    2. Don’t know

    Thanks,
    Ewan

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