138 IBM Cognos Dynamic Cubes
6.2.2 Manually merging source cube objects
It is possible to manually merge objects in a virtual cube that could not be merged
automatically. The following sections describe how to manually define these objects.
Defining a virtual dimension
Figure 6-4 on page 136 shows source cube gosldw_sales that has a dimension named Time,
and source cube gosldw_target has a dimension named Time-month-target. Because these
dimensions have different names, they were not merged automatically, so two virtual
dimensions Time and Time-month-target are added to the virtual cube. If both dimensions
contain the same structure and data, you could manually merge them into one virtual
dimension named Time.
Use the following steps to merge Time and Time-month-target dimensions.
1. In the Project Explorer, select the Time-month-target dimension.
2. Right-click and select Delete.
3. Select the Time dimension. In the column for the gosldw_target cube, click the
Dimension Editor button. Figure 6-6 shows its location.
Figure 6-6 Virtual Dimension Editor
4. In the Select Source Object window, select the Time-month-target dimension.
5. Click OK.
Defining a virtual hierarchy
Use the following steps to create a virtual hierarchy:
1. To open the Hierarchy Editor, in the Virtual Dimensions column, double-click the row that
has the Time dimension.
2. Because both Time and Time-month-target dimensions have a hierarchy named Time in
the source cubes, a virtual hierarchy named Time was automatically created, merging both
source hierarchies, as shown in Figure 6-7 on page 139. If these dimensions had
hierarchies with different names, two separate hierarchies would be created. Similar to the
Note: You cannot reference a source object more than once in a virtual cube.
Click here to
open dimension
Chapter 6. Virtual cubes 139
dimensions, you can manually merge two hierarchies that have the same structure and
data.
Figure 6-7 Virtual Hierarchy Editor
Viewing virtual levels
When you create a virtual cube, Cognos Cube Designer adds levels from the source cubes to
the virtual cube. Source cubes that contain identical levels in a hierarchy are merged as
virtual levels.
If levels in the source cubes are not identical, level names from the first source cube are used
as the names of the virtual levels. If one source cube contains more hierarchy levels than the
second source cube, the extra levels are added as the lowest levels of the virtual hierarchy.
To see the virtual levels, in Project Explorer, double-click the hierarchy for which you want to
see the levels. Figure 6-8 shows how levels in the Time hierarchy were merged.
Figure 6-8 Viewing virtual levels
Defining virtual members
Any members that do not have matching level keys are added to the virtual cube as new
virtual members.
If a virtual member is not merged correctly, or could not be automatically merged, you may
manually merge two source members. You may also delete redundant virtual members.
When you manually merge a member, it is removed from the list of members that are
automatically merged.

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