How many dimensions in an OLAP cube?

For a typical measure there are 3 to 8 dimensions. In a simple case, you may have Market, Product, Time. Telling where it was sold, what was sold, when it was sold. Or, you could have Geography, Channel, Customer, Product, Time In financial applications, you may have a few measure dimensions to select the data you want: scenario, version, account and then add a time dimension, an entity dimension The issue of dimensionality is discussed in detail in The Multidimensional Data Modeling Toolkit, you may want to take a look at that.