Oracle Tips  by Burleson Consulting

The Data Warehouse Development Life Cycle

Online Analytical Processing and Oracle

Data Warehouses And Multidimensional Databases
There is also a difference between the presentation style of OLAP systems and multidimensional databases. OLAP engines generally have an SQL-like interface that allows ad hoc queries to be processed against the warehouse data, using SQL select operations, and producing output lists of query results. Multidimensional databases use a spreadsheet metaphor as the front end, and the end user models the dimensions and views the resulting summary as a cross-tabulation in the spreadsheet. Table 5.3 shows the differences between the presentation and display styles for OLAP and MDDB servers.

Feature                                           OLAP                       MDDB
Presentation display                   List                      Crosstab
Extraction                                Select                  Compare
Series variable dimensions           Columns                User-defined

Table 5.3 Differences between OLAP and MDDB presentations.

The base rule is simple: If the data looks like it will fit well into a spreadsheet, it is probably well-suited to an MDDB--or at least an MDDB representation. However, it is not always best to apply this general rule to data warehouse architectures. Many techniques exist for allowing Oracle databases to appear to be OLAP servers or multidimensional databases.

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This is an excerpt from "High Performance Data Warehousing".

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