Touted by IBM as offering the power of Arbor Essbase OLAP Server 5 with the robustness of DB2, IBM's DB2 OLAP Server 1.0 integrates Essbase's online analytical processing (OLAP) server and APIs with IBM's DB2 family of relational databases. DB2 OLAP Server uses a star schema structure to store data in DB2. Typically, the Essbase engine calculates the data in the star schema. You can use Essbase clients or traditional SQL tools to access the data. DB2 OLAP Server manages the relational storage within the star schema and the relationship between Essbase and DB2.
Nigel Pendse, co-author of The OLAP Report (http://www.olapreport.com), jokingly refers to the DB2 OLAP Server as a "diesel Essbase" because it merges the two dissimilar technologies at high cost. "IBM did a fine job of implementing the DB2 layer," observes Pendse. "The problem is that IBM is converting a highly optimized, patented compressed cube structure into vanilla relational rows. These rows take about twice as much space to store and have less appropriate, bulkier indexing. Both factors combine to make access to the data much slower."
Nevertheless, the DB2 OLAP Server is an attractive option for DB2 shops that want an easy-to-implement OLAP solution. You install it with one CD-ROM. As with Essbase, you create a database outline, define dimensions and members, and specify dimensions as dense or sparse. However, in DB2 OLAP Server, you have to specify an Anchor tag, which is akin to Essbase's Accounts tag.
DB2 OLAP Server operates on Windows NT, OS/2, AIX, and Solaris. It maintains and analyzes data stored in IBM's DB2 family, including DB2 Universal Database (UDB), DB2 for OS/390, and DB2 for OS/400. Aside from the relational storage management function, DB2 OLAP Server offers the same functionality as Essbase. According to Arbor, 98 percent of the OLAP code in DB2 OLAP Server is the same as the OLAP code in Essbase. Queries perform similarly, although DB2 OLAP Server's load and calculation processes take longer because of the tight DB2-to-Essbase mapping.