Chapter 3 Visualization
Section 4 OLAP
Page 6 Pivoting & Aggregation

Objectives

The objectives of this section are:
to introduce tools used for multidimensional data analysis
to explain the basic concepts of OLAP

Outcomes

By the time you have completed this section you will be able to:
define OLAP,
and understand it’s capabilities.

Pivoting

Pivoting does as the name suggests and pivots the data based on the axes, it is also referred to as rotating the data. Some common pivoting procedures are swapping the rows and columns, moving one of the row dimensions into the column dimension or vice versa. Figure 7 below shows the swapping of the Time and Location dimensions.

Pivoting dimensions

Aggregation

In order to have a fast response time, OLAP systems must pre-compute some data because the more calculations that OLAP needs to perform in order to produce an expected piece of information by the user the longer the response time. In order to speed things up, OLAP systems pre calculate values and stores these values in a database, this process is known as pre-aggregation.