IBM Cognos User Manual page 195

Constraints
In developing your partitioning strategy, consider the following constraints:
v You cannot use auto-partitioning if Consolidate is disabled on the General tab
of the PowerCube property sheet, or if Optimization is set to any method other
than Auto-Partition or Default, such as Categories or Direct create.
v Auto-partitioning is disabled if your model has a custom view with a cloaked
primary-drill category. You can run Check Model to receive a warning message
about this condition, allowing you to uncloak the drill category or otherwise
redesign your model to allow auto-partitioning to proceed.
v Although auto-partitioning may occasionally partition categories from
dimensions that have alternate drill-down paths, you can only use manual
partitions on categories in the primary drill-down path.
v You cannot auto-partition cubes that use externally rolled-up or before-rollup
calculated measures. However, you can partition cubes that use calculated
columns.
v You should avoid partitioning dimensions that are frequently updated with new
categories, or that contain alternate drill-down structures, leaf-level
subdimensions, or special categories.
v You cannot specify partition numbers for leaf categories, drill categories, or the
main root category.
v You can add new categories to an existing partition level. For example, you can
add a new region, which will result in a new partition for that region. However,
you cannot add new partition levels to a model if any cube in that model uses
incremental update. Instead, you must repartition the model and rebuild the
cube, incorporating all the data from all increments.
Partitioning Checklist
When partitioning, confirm the following:
v Ensure that you set up clearly recognized, business-related groupings in your
source data, such as commodity types or customer sales channels, and import
them into your model as a new data source column.
v Because you cannot set different partition sizes for different parts of the cube,
consider reorganizing your data so that some cubes can be optimized for
high-level summary reports and others for low-level detail reports.
v Add calculated columns, such as product number ranges or alphabetically sorted
customer sets, to regroup your data.
v On the dimension map, manually create alternate drill downs with manual
levels and create categories representing subdivisions, such as geographic
regions, and use the category viewer to drag lower-level categories to associate
them with the appropriate parent categories.
If you do not need these manually added categories in every cube, create a
dimension view and use the Suppress command to remove the unnecessary
levels of detail. However, suppressed categories cannot be partitioned and
suppressing the manual levels in a custom view will reduce the effectiveness of
your overall partitioning strategy.
For more information about suppressing categories, see "Omit Categories Using
Suppress" on page 134.
Chapter 8. PowerCubes in Production Environments
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