IBM Cognos User Manual page 191

For time-based cubes, child cubes are always published with the time-based cube.
Disabling publishing for a child cube only restricts publishing of that cube
individually.
Enable Crosstab Caching
Use this option to store summaries for the initial crosstab in the cube. These
summaries help improve run-time access for your OLAP report users.
Block Totals for Parents with Excluded Children
This option controls whether values are displayed against categories that are the
rollup ancestors of categories that have been excluded in a custom view. When this
option is selected, an ancestor category displays denied instead of a value. To see
values, users must drill down to categories without excluded descendants.
Use Multiple Data Sources
By using multiple data sources for your model, you can reduce the total volume of
data processed and thereby shorten processing times in Cognos Transformer. If
used in combination with calculated columns, multiple data sources can minimize
or eliminate the need to create database table joins in an external data access tool.
Using multiple data sources also enables measure allocation.
For example, suppose your product, customer, and order data is stored in a set of
tables. If you were to use this data from a single source, you would need separate
tables for Product, Customer, CustomerSite, Order, and OrderDetail. This source
would contain many duplicate values, and the joins between the tables would be
relatively complex.
Instead, you create three separate sources for Products, Customer/Site, and
Order/Order Detail data. The volume of data contained in each is less than that in
the single source, and there are only simple joins between Customer and
CustomerSite tables, and Order and OrderDetail.
Remember that each source must contain sufficient data to establish context within
the dimension map. You cannot perform database table joins in Cognos
Transformer.
Procedure
1. Using a data access tool such as IBM Cognos Impromptu or Framework
Manager, create each of the data sources required for your model.
2. From the Welcome page, click Create a new model to use the New Model
wizard to add the largest structural data source to your model.
Tip: If you are already in Cognos Transformer, click New from the File menu.
3. From the Edit menu, click Insert Data Source and add the additional structural
data sources to the Data Sources list.
4. Repeat to add the transactional data sources to the Data Sources list.
Consolidate Data in PowerCubes
In Cognos Transformer, consolidation summarizes measure values during cube
creation, so that fewer summarizing calculations are required in the OLAP
reporting component. Consolidation reduces cube size and, if you enable
auto-partitioning, does not slow down cube creation.
Chapter 8. PowerCubes in Production Environments
177