Bridging the Gap between OLAP and SQL
Jens-Peter Dittrich, Donald Kossmann, Alexander Kreutz, Er Kreutz · 2005
In the last ten years, database vendors have invested heavily in order to extend their prod-ucts with new features for decision support. Examples of functionality that has been added are top N [2], ranking [13, 7], spreadsheet computations [19], grouping sets [14], data cube [9], and moving sums [15] in order to name just a few. Unfortunately, many mod-ern OLAP systems do not use that functional-ity or replicate a great deal of it in addition to other database-related functionality. In fact, the gap between the functionality provided by an OLAP system and the functionality used from the underlying database systems has widened in the past, rather than narrowed. The reasons for this trend are that SQL as a data definition and query language, the re-lational model, and the client/server archi-tecture of the current generation of database products have fundamental shortcomings for OLAP. This paper lists these deficiencies and presents the BTell OLAP engine as an exam-ple on how to bridge these shortcomings. In addition, we discuss how to extend current DBMS to better support OLAP in the future. 1