XOLAP (extended online analytic processing) is a variation on the role of OLAP in business intelligence. Specifically, XOLAP is an Essbase multidimensional database that stores only the outline metadata and retrieves data from a relational database at query time. XOLAP thus integrates a source relational database with an Essbase database, leveraging the scalability of the relational database with the more sophisticated analytic capabilities of a multidimensional database. Your business needs determine whether OLAP or XOLAP is best suited to your environment.
OLAP and XOLAP store the metadata outline and the underlying data in different locations:
In OLAP, the metadata is located in the Essbase database, and the underlying data is also located in the Essbase database.
In XOLAP, the metadata is located in the Essbase database while the underlying data remains in your source relational database.
The differences in the locations of the metadata and data are key to understanding how XOLAP can be of benefit because these differences affect the functionality of OLAP and XOLAP.
OLAP lends itself to traditional relational data storage and data analysis. XOLAP lends itself to operations supported in mixed or “hybrid” environments such as Hybrid Analysis and Advanced Relational Access (familiar to users of Essbase and Integration Services). Many of the basic concepts of Hybrid Analysis and Advanced Relational Access have been folded into the functionality of XOLAP cubes in Essbase Studio.
For information on guidelines and restrictions in using XOLAP and how to designate models for XOLAP, see the Essbase Studio online help.