5.9.5  Transformations and Faults

When a particular data view component (Chart, Table, etc.) is materialized, the materialization process caches the data in the underlying Worksheet Data Block to which the component is bound. This allows the component to rapidly query the cached dataset rather than the database.

In order for the underlying Data Block to be materialized, any Viewsheet selections (e.g., Selection Lists) that filter the Data Block must be applied directly to the Data Block itself, rather than to any precursor data blocks. For example, consider the following Worksheet:

 

This Worksheet is used by a Viewsheet that has the following component bindings:

Chart (data view component) bound to the resultant 'Query1' Data Block

Range Slider bound to the 'NJ Orders1' Data Block

Selection List bound to the 'NY Orders1' Data Block

To materialize the 'Query1' Data Block for use by the Chart, the materialization process must first transform the Viewsheet by “moving up” the selection components to operate on the resultant Data Block, as shown below:

 

The automatic trans­formation is internal, and does not alter the actual Viewsheet.

This transformation process is done internally and automatically during the materialization process. The result of the transformation is a new representation that preserves the same data as the original Data Block but is more appropriate for querying. However, when the transformation cannot be accomplished in a way that preserves the data intact, Enterprise Manager displays a “fault” in the 'Optimize Plan' dialog box. The fault means that the Data Block in question cannot be materialized.

In many of these instances, you may be able to facilitate materialization by “moving the selection up.” To do this, evaluate the placement of your selection components, and try to relocate them (i.e., move them up) to filter the resultant Data Block rather than the precursor Data Blocks. By doing this you may enable Enterprise Manager to materialize the problem Data Block.

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