More and more Oracle customers are finding value in federating their EPM cubes with existing relational data stores such as data marts and data warehouses (for brevity, data warehouse will refer to all relational data stores). This post explains the concept of federation, explores the consequences of allowing hierarchical structures to get out of synchronization, and shares options to enable this synchronization.
In OBI, federation is the integration of distinct data sources to allow end users to perform analytical tasks without having to consider where the data is coming from. There are two types of federation to consider when using EPM and data warehouse sources: vertical and horizontal. Vertical federation allows users to drill down a hierarchy and switch data sources when moving from an aggregate data source to a more detailed one. Most often, this occurs in the Time dimension whereby the EPM cube stores data for year, quarter, and month, and the relational data sources have details on daily transactions. Horizontal federation allows users to combine different measures from the distinct data sources naturally in an OBI analysis, rather than extracting the data and building a unified report in another tool.
Federation makes it imperative that the common hierarchical structures are kept in sync. To demonstrate issues that can occur during vertical federation when the data sources are not synchronized, take the following hierarchies in an EMP application and a data warehouse:
Figure 1: Unsynchronized Hierarchies
Notice that Colorado falls under the Western region in the EPM application, but under the Southwestern region in the data warehouse. Also notice that the data warehouse contains an additional level (or granularity) in the form of cities for each region. Assume that both data sources contain revenue data. An OBI analysis such as this would route the query to the EPM cube and return these results:
Figure 2: EPM Analysis – Vertical Federation
However, if the user were to expand the state of Washington to see the results for each city, OBI would route the query to the data warehouse. When the results return, the user would be confronted with different revenue figures for the Southwest and West regions:
Figure 3: Data Warehouse – Vertical Federation
When the hierarchical structures are not aligned between the two data sources, irreconcilable differences can occur when switching between the sources. Many times, end users are not aware that they are switching between EPM and a data warehouse, and will simply experience a confusing reorganization in their analysis.
To demonstrate issues that occur in horizontal federation, assume the same hierarchies as in Figure 1 above, but the EPM application contains data on budget revenue while the data warehouse contains details on actual revenue. An analysis such as this could be created to query each source simultaneously and combine the budget and actual data along the common dimension:
Figure 4: Horizontal Federation
However, drilling into the West and Southwest regions will result in Colorado becoming an erroneously “shared” member:
Figure 5: Colorado as a “Shared” Member
In actuality, the mocked up analysis above would more than likely result in an error since OBI would not be able to match the hierarchical structures during query generation.
There are a number of options to enable the synchronization of hierarchical structures across EPM applications and data warehouses. Many organizations are manually maintaining their hierarchical structures in spreadsheets and text files, often located on an individual’s desktop. It is possible to continue this manual maintenance; however, these dispersed files should be centralized, a governance processes defined, and the EPM metadata management and data warehouse ETL process redesigned to pick up these centralized files. This method is still subject to errors and is inherently difficult to properly govern and audit. For organizations that are already using Enterprise Performance Management Architect (EPMA), a scripting process can be implemented that extracts the hierarchical structures in flat files. A follow on ETL process to move these hierarchies into the data warehouse will also have to be implemented.
The best practices solution is to use Hyperion Data Relationship Management (DRM) to manage these hierarchical structures. DRM boasts robust metadata management capabilities coupled with a system-agnostic approach to exporting this metadata. DRM’s most valuable export method allows pushing directly to a relational database. If a data warehouse is built in tandem with an EPM application, DRM can push directly to a dimensional table that can then be accessed by OBI. If there is a data warehouse already in place, existing ETL processes may have to be modified or a dimensional table devoted to the dimension hierarchy created. Ranzal has a DRM accelerator package to enable the synchronization of hierarchical structures between EPM and data warehouses that is designed to work with our existing EPM application DRM implementation accelerators. Using these accelerators, Ranzal can perform an implementation in as little as six weeks that provides metadata management for the EPM application, establishes a process for maintaining hierarchical structure synchronization between EPM and the data warehouse, and federation of the data source.
While the federation of EPM and data warehouse sources has been the primary focus, it is worth noting that two EPM cubes or two data warehouses could be federated in OBI. For many of the reasons discussed previously, data synchronization processes will have to be in place to enable this federation. The previous solutions for maintaining metadata synchronization may be able to be adapted to enable this federation.
The federation of EPM and data warehouse sources allows an enterprise to create a more tightly integrated analytical solution. This tight integration allows users to transverse the organization’s data, gain insight, and answer business essential questions at the speed of thought. As demonstrated, mismanaging hierarchical structures can result in an analytical solution that produces unexpected results that can harm user confidence. Enterprise solutions often need enterprise approaches to governance; therefore, it is often imperative to understand and address shortcomings in hierarchical structure management. Ranzal has a deep knowledge of EPM, DRM, and OBIEE, and how these systems can be implemented to tightly work together to address an organization’s analytical and reporting needs.