Cube Updates; Automatic Creation Of Multifile Cubes - IBM Cognos User Manual

The placeholder categories are: Early Dates, Late Dates, or Invalid Dates. To lock
a dimension, preventing Cognos Transformer from adding unwanted categories,
we recommend that, in the Dimension property sheet, you prohibit the automatic
creation of new categories.
When you are making changes to your model, you should periodically clean up
fragments that can cause generation errors by saving your model as an .mdl file
rather than a .py? file. If your model has categories that are not used, we
recommend that you delete them by running the Clean House command. For
more information, see "Delete Inactive Categories" on page 178.
The Clean House feature should be used with caution, as it may cause problems
with consumers' reports in IBM Cognos. If you intend to delete inactive categories,
we recommend that you advise your consumers so that they can remove those
categories, or members, from their reports when they are directly referenced.
Otherwise, they may receive an error the next time they run their reports.
Note: If your model contains incrementally updated cubes, you must retain all of
their categories for the cubes to remain valid.

Cube Updates

You should alert your report users whenever you change a cube object, because the
change may not be obvious when they look at the report.
When you enable the incremental update feature for a cube, Cognos Transformer
appends the new data to the existing cube. When you disable incremental update,
Cognos Transformer overwrites the existing cube. For more information, see
"Setting up Placeholder Categories for Cube Groups" on page 186.
To rebuild an incrementally updated cube, you must delete the old .mdc file and
recreate the entire cube.
For information about updating published cubes, see "Updating Published
PowerCubes and PowerCube Connections" on page 186.

Automatic Creation of Multifile Cubes

Each PowerCube, or .mdc file, cannot currently be larger than 2 GB. If you plan to
build a cube that would result in an .mdc file larger than 2 GB, enable creation of
multifile PowerCubes. This process is controlled by the MultiFileCubeThreshold
setting in the cogtr.xml file. The default value of this setting is 0, which means that
multifile cube generation is disabled.
For more information on cogtr.xml file settings, see "cogtr.xml File Settings" on
page 326.
The multifile cube contains one file with the .mdc extension, and one or more files
with the .mdp (multidimensional partition) extension. To PowerCube users,
multifile cubes appear as a single, large cube.
Note: Multifile cubes must be partitioned so that the contents of the partitions can
be distributed across the required number of .mdp files.
When building a multifile PowerCube, Cognos Transformer determines the number
of output .mdp files that are needed by dividing the number of data records in the
cube by the MultiFileCubeThreshold value, and rounding up the result. Cube
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IBM Cognos Transformer Version 10.1.1: User Guide