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IgnoreUnrelatedDimensions in Analysis Services 2008

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    Once of the more common issues with working with data in a cube is that it does not always line up like we expect. This is usually a combination of our interpretation of how SSAS will handle our business and a lack of understanding of some feature, option, property or toggle switch we forgot to flip. None of these occurs more often than in working with a set of dimensions that intersect multiple fact tables or measure groups, but not both. This can cause some strange behavior along the dimensionalities that don’t intersect.

    The property IgnoreUnrelatedDimensions is set at the measure group level and allows the developer to control the way this will be handled. IT has two options

  1. True – DEFAULT – When the property is set to true, the measure group ignores the fact that the dimension are not related to it and displays the current amount, even though this is really not valid.

    For Example in AdventureWorks2008, the SalesReasons Dimension is Not Related to Reseller (See below)

    clip_image001

    Let’s Slice these by a related and unrelated dimension. Let’s take Sales Reasons and slice it by Reseller (Unrelated) and Internet Sales Order Details (related) and see what we come up with.

    You’ll notice when we drop an unrelated dimension onto the screen we immediately get the current value for that dimension for all measure rows

    clip_image002

    We do have another option, however:

  2. False – Obviously not Default – When this is set, the dimension ignores those other unrelated dimensions. Yes I know that false doesn’t make sense when the property is call "Ignore", but who ar ewe to judge. Oh wait, we ‘re the developer community:) . All kidding aside, it should default to false, but just keep this in mind. See the difference?

    clip_image003

    Any Unrelated Dimension is now Ignored.

    As Always – please post your questions to the BIDN forums. Thanks for reading!

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