Relational Dimensions

A relational dimension is a structure that organizes data. Examples of commonly used dimensions are Customers, Time, and Products.

Relational dimensions provide improved query performance because users often analyze data by drilling down on known hierarchies. An example of a hierarchy is the Time hierarchy of year, quarter, month, day. The Oracle Database uses these defined hierarchies by rewriting queries that retrieve data from materialized views rather than detail tables.

Typical relational dimension tables have the following characteristics:

• A single column primary key populated with values called warehouse keys.

  Warehouse keys that provide administrative control over the dimension, support techniques that preserve dimension history, and reduce the size of cubes.

• One or more hierarchies that are explicitly defined as dimension objects. Hierarchies maximize the number of query rewrites by the Oracle server.