OLAP cube

An OLAP cube is a special way to organize information, like a data cube. It helps people look at big amounts of data quickly. The data is arranged in many directions, making it easy to see patterns.

OLAP stands for online analytical processing. It is a computer method that helps people study data to find useful ideas. With an OLAP cube, businesses and researchers can ask hard questions and get answers faster than with normal databases. This tool is important for making good choices using data.

Terminology

A cube is a special way to organize information, like a spreadsheet but in more than two directions. Think of a company that wants to see its money details by what they sell, when they sell it, and where they sell it. These different views of the data are called dimensions.

Each spot in the cube has a number that shows something important about the business, like how much they sold or spent. This helps people see patterns and make better choices.

Hierarchy

The elements of a dimension can be organized in a hierarchy. This means they have parent-child relationships. Usually, a parent shows the total of its children. These parents can also be grouped together as children of another parent.

For example, May 2005 is part of the Second Quarter of 2005, which is part of the Year 2005. Cities belong to larger regions, products belong to product groups, and expenses belong to types of spending.

Operations

When we think of data as a cube with different parts, it becomes easier to analyze. Users can move around the cube by choosing what to look at, which is called "slice and dice." Common ways to work with the cube include slicing, dicing, drilling down/up, rolling up, and pivoting.

Slice means picking a part of the cube by choosing one value for a part of it, making a new, smaller cube.

Dice lets the user pick specific values from several parts of the cube to create a smaller cube.

Drill Down/Up lets the user move between general and detailed levels of data.

Roll-up means adding up data along a part of the cube, like finding totals.

Pivot lets the user turn the cube to see different sides of the data. For example, cities could be shown up and down, and products side to side, and after turning, products could be shown up and down and time side to side.

Mathematical definition

In database theory, an OLAP cube is a way to organize information from databases. Imagine it like a box where each side shows different details. For example, you might look at three main things—like the type of product, the store location, and the time of year. These three things act like the sides of the box.

Because we usually see things on paper or screens, which are flat, we often take "slices" of this box to see it better. This means we focus on just two of the three things at a time. The result looks like a table where one side lists the products and the other side lists the stores, and where they meet, you see numbers that tell you something important about that product in that store. This helps us understand big sets of data more easily.