Advanced Dimension Properties
In addition to basic properties such as name, data source, and description, MSAS supports numerous advanced dimension properties. Knowing which ones to change can help you customize your cube’s behavior as needed.
As you saw in the dimension security example, we could easily restrict a role from viewing ALL level within a dimension. In some cases, each cube user should only see her own data and not be permitted to see totals on the ALL level which is created by default. You can take care of this easily by turning off the ALL level within the Dimension Properties window: Simply click on the dimension, choose Edit, select the Advanced tab within the Properties pane, and change the All Level setting to NO.
The default member property is used when a particular member of the dimension isn’t specified. If you don’t specify the default member property and you don’t specify a dimension member within your query, MSAS shows you all levels within that dimension. For example, if we look at the default view of the sales cube, we see sales for all products by default. However, let’s see what happens if we change the default member to Drink (see Figure 12).
Figure 12 Product dimension shows DRINK instead of ALL Products.
Notice that the time dimension defaults to 1997, so unless you specify a certain member in your queries, you will always see measure values that apply to 1997.
You might have noticed that the Dimension wizard allows you to mark a dimension as Changing, and you can accomplish the same from Dimension Properties window. A Changing dimension allows more types of changes without the need to reprocess the dimension. One annoying nuance of MSAS 2000 is that it requires you to process a dimension if you change its structure or members. Dimension tables are usually small, and typical dimensions only take a few seconds (or minutes) to process; however, all cubes that contain the changed dimension will have to be processed as well and cube processing might take hours. Of course, none of the users can access the cube while it is processed, so marking a dimension as Changing could help you from interrupting your user queries less frequently. With changing dimensions, you can add, change, or delete levels of the dimension below the top level and above the bottom level without having to fully reprocess the dimension. For example, I could delete the brand name level within the Products dimension; when I save the dimension, MSAS will simply ask me to process the dimension incrementally—such processing does not require me to reprocess cubes so that my cubes will continue being accessible.