What Gets Linked

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There are a few gotchas with linked universe, and the first one is that not everything is linked. Not linking everything is both a help and a headache. Universe parameters are not linked. Therefore, within the derived universe, you still need to set Controls for query execution time and result-set size as well as SQL settings that determine if users can create complex queries or create queries that involve multiple fact tables.

Classes and objects generally get linked. However, within the object properties, list of values names, and therefore, customizations do not get linked. For example, if you rename the list of values on Customer ID to CUSTID, the derived universe shows a nonsensical name of ~00T0001. When a user tries to use a customized list of values that has been exported to the repository, the user gets an error “No data to fetch.” For a list of values that has not been exported, the user can access the list of values. The physical query file (~00T0001.lov) is stored in UserDocs\Universe\DerivedUniverse. As a workaround, create new objects that need customized lists of values within the derived universe (although even this approach is still somewhat buggy).

Caution 

In a kernel universe, do not customize lists of values or use the Export with Universe setting.

Join definitions are linked to the derived universe, but not the contexts. The vendor argues that this is the correct procedure, as the derived universe may contain additional joins and contexts. This is true; however, the current approach builds an incorrect universe that contains loops. I would like to see the contexts brought into the derived universe. A universe designer could then add new joins to existing contexts or create new contexts altogether. With the current approach, all contexts must be re-created in the derived universe.

Aggregate navigation settings are linked. If you add a new aggregate table within the derived universe, you can define additional incompatibilities; all the original incompatibilities are still preserved.

Custom hierarchies are not linked. However, as you build new custom hierarchies in the derived universe, when an object name changes in the kernel universe, the new name is included in the derived universe’s custom hierarchy. The following table summarizes which components get linked or not:

Universe Component	Linked	Not Linked
Universe parameters		Ö
Classes and objects	Ö
List of values customizations		Ö
Joins	Ö
Contexts		Ö
Aggregate navigation	Ö
Custom hierarchies		Ö

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