Considerations for Modifying an EPM Warehouse
The prepackaged MDW data model is designed to facilitate the introduction of a new dimension, a new attribute on an existing dimension table, a new dimension and/or a new fact based on an existing fact table. Any modifications that you make to the overall solution, including data mart content, will affect the reporting results. Consider the following questions when modifying the data model and developing reports.
Before modifying the data model, determine:
What business intelligence reporting tool you will use— relational online analytic processing (ROLAP) or multidimensional online analytic processing (MOLAP).
Whether you must build aggregate fact tables (if using ROLAP).
If so, determine what aggregate levels of each dimension to use for this fact table.
The typical profile of your end-users.
Evaluate Dimension Requirements
To ensure that the dimensions meet the needs of your business, determine:
The dimensions in the delivered data mart that you want to keep and the ones that you can eliminate.
The dimensions that you must create that are not part of the delivered data mart.
The changes that you must make to delivered dimensions.
If you alter an existing dimension or add a new dimension, determine:
Whether this is a dimension or merely an attribute of an existing dimension.
The hierarchies in this dimension.
The hierarchy levels in each hierarchy of this dimension.
The attributes of this dimension.
Whether you are altering the lowest level of an existing dimension.
Whether you have facts at this level.
Whether your multidimensional analysis will still work.
Evaluate Measure Requirements
To ensure that the measures you use meet the needs of your business, determine:
The measures in the delivered data mart to keep and those to eliminate.
The measures that you must create that are not part of the delivered data mart.
What changes you must make to delivered measures, such as changing calculations or populating required fields.
If you alter an existing measure or add a new measure, determine:
Whether they are base measures that you can store on a row by row basis, or are runtime calculations that you must define in the reporting tool.
What dimensions qualify this measure.
Whether this measure is an addition to an existing fact table, or must be part of a new fact table.
Whether you will use this measure along with other measures on the same report.