Working with Online Analytical Processing (OLAP)

Updated: 17 July 2006

Online analytical processing (OLAP) allows you to access aggregated and organized data from business data sources, such as data warehouses, in a multidimensional structure called a cube. Microsoft SQL Server 2005 Analysis Services (SSAS) provides tools and features for OLAP that you can use to design, deploy, and maintain cubes and other supporting objects. Before you start integrating cubes and other OLAP functionality into your business intelligence solutions, make sure you are familiar with the following concepts and decisions.

You can define and instantiate OLAP objects directly in an Analysis Services database (called online mode or sometimes direct connect mode) or within an Analysis Services project (called project mode). Generally, you will develop your OLAP solution within an Analysis Services project. For more information, see Developing Analysis Services Solutions and Projects.

You generally define OLAP objects based on an existing data source, such as a data warehouse or production database. However, you can also define OLAP objects without a data source and then have the Schema Generation Wizard create the underlying relational schema based on the OLAP objects defined in an Analysis Services project. For more information about working with relational schemas, see Working with Relational Schemas.

Dimensions, attributes, and hierarchies are OLAP objects that you define and configure at the Analysis Services database level. These OLAP objects exist independent of any OLAP cubes and can be used in one or more cubes. To a limited extent, these objects can be customized within each cube. For more information about defining and configuring dimensions, attributes, and hierarchies, see Defining and Configuring Dimensions, Attributes, and Hierarchies. For conceptual information about dimensions, attributes, and hierarchies, see Dimensions (Analysis Services).

Cubes are OLAP objects consisting of related measures and dimensions that you configure within an Analysis Services database. You can define and configure multiple cubes within a single database and each cube can use some or all of the same dimensions. You can also define a single cube that contains multiple measure groups in the same database rather than defining separate cubes. When you define a cube with multiple measure groups, you need to define how dimensions relate to each measure group and customize, as appropriate, dimension objects within each cube and measure group. When defining a cube, you also define advance cube properties, including calculations, KPIs, actions, partitions and aggregations, perspectives and translations. For information about defining and configuring cubes and cube properties, see Defining and Configuring Cubes and Cube Properties. For conceptual information about cubes and cube properties, see Cubes (Analysis Services).

Release History

17 July 2006

Changed content:
  • Revised content, changing term direct connect mode to online mode.

14 April 2006

Changed content:
  • Updated conceptual material to improve clarity.
  • Removed content about traditional OLAP or Unified Dimensional Model.
New Content:
  • Added content about direct connect mode versus project mode.