Control When the Source Data Is Read

In models with multiple data sources, you can control when a data source is read. For example, a data source can be read during category generation, during cube creation, or both. You can use this capability to avoid unnecessary processing, resulting in a more efficient model design.

Here are some typical scenarios:

  • After Cognos® Transformer reads your purely structural data sources and populates your model with data for the required category structure, you can change the timing so that these static categories are not regenerated every time you create the PowerCube.
  • For structural data sources that frequently change, you can set the timing to update the categories whenever you create the PowerCube.
  • For transactional data sources, where the measure values are constantly changing, you can select the Default method of PowerCube creation.

Procedure

  1. In the Data Sources list, right-click the data source for which you want to control the timing and click Properties.
  2. On the General tab of the Data Source property sheet, under the Timing box, select the Generate categories check box.

    This will cause the data source to be queried whenever categories are generated.

  3. Select the PowerCube creation check box and choose what will occur when cubes are created or updated:
    • Default

      Cognos Transformer reads all columns in the source that relate to levels in the model to see if they are associated with measures. If the source is purely structural, the cube is not created or updated, and an error message appears. Use this option in a production environment for transactional data sources and structural data sources that contain non-static data.

    • Generate categories only

      Cognos Transformer queries only for structural information when the Create Selected PowerCube and Update Selected PowerCube commands run. If there are measures in any of the source files, they are not retrieved.

    • Create the PowerCubes

      Cognos Transformer queries the source and creates or updates the cubes, even if the source lacks measures. In a design and development environment, use this option to override error messages and continue processing.

  4. Click OK.