Introduction to SQL Server 2000 Analysis Services: Exploring Virtual Cubes - Page 5

After we create a virtual cube, we must process it before client applications can browse it. The necessary internal links to the specified dimensions and measures in the underlying cubes are established through processing the virtual cube. While the linking operation that is involved in processing is typically quick in itself, we need to keep in mind that initialization of processing our virtual cube will automatically trigger the processing of any underlying cubes that themselves require processing. This can add significant time to the process, and needs to be included in planning when taking the virtual cube route. Ideally, the underlying cubes will be preprocessed, but this is certainly not a requirement, and may not be the best strategy in certain situations.

The Finish the Virtual Cube Wizard dialog appears.

18. Name the virtual cube Budget vs Actual by typing into the Virtual Cube Name box.

NOTE: Period characters ("."), among others, are restricted from use in the virtual cube name.

19. Ensure that the Process Now radio button is selected (the default).

This, the last step of the Virtual Cube Wizard, presents us with the option to process the virtual cube now or at a later time. As we have stated earlier, a virtual cube must be processed before its data can be viewed. Virtual cube processing is much faster if all the underlying cubes have already been processed. Depending upon the size of any unprocessed cubes, processing time for the virtual cube can become significant.

The Finish the Virtual Cube Wizard dialog, with our selections, appears as shown below.

Illustration 9: The Completed Finish the Virtual Cube Wizard Dialog

20. Click Finish.

After clicking Finish above, we see that the Process dialog appears, logging the significant processing events and then presenting a green Processing Completed Successfully message at the bottom of the dialog, as depicted in Illustration 10.

Illustration 10: The Process Dialog (Compressed View) Indicates Completion

We need to be aware that information consumers can only view data from a newly processed virtual cube after they reconnect to the server computer. We also need to note that we must process dependent virtual cubes after we make structural and nonstructural changes to the underlying source cube(s) so that end users continue to have access to them. (If the structures of the underlying cubes have not changed since they were last processed, the processing is faster than processing the component cubes individually.) The changes to which I refer include:

• Adding or changing a calculated member;
• Adding or changing a calculated measure;
• Changing security roles;
• Changing the Description property value.

Virtual cube users connected to the server computer are not affected, as long as they remain connected while we are making nonstructural changes. Until we process the dependent virtual cubes, however, end users who connect cannot see them.

21. Click Close.

The Process dialog closes and the new Virtual Cube Editor (a customized version of the Cube Editor) appears, as shown.

Illustration 11: The Virtual Cube Editor (Compressed View)

Note that the Virtual Cube Editor does not have a Schema tab, as does the standard Cube Editor.

22. Close the Virtual Cube Editor.

We are returned to the main Analysis Manager console window.

23. Expand the Cubes folder, if necessary, once again.

We see the Budget vs Actual Cube appear, as shown in the illustration below.

Illustration 12: The new Budget vs Actual Cube Appears (Compressed View)

Analysis Manager identifies virtual cubes with the "double" cube icon, as shown above (circled in red).