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Dimensions of study OLAP

What is a Dimension?
A Dimension is a structural attribute of a Cube that is a list of related names–
known as Members–all of which belong to a similar category in the user’s
perception of a data. For example, months and quarters may make up a Months
dimension; likewise all cities, regions and countries may make up a Region
dimension. A Dimension acts an index for identifying values within a
multidimensional array and offers a very concise, intuitive way of organizing and
selecting data for retrieval, exploration and analysis. Dimensions are the business
parameters normally seen in the rows and columns of a report.
How many dimensions can an OLAP cube have?
three dimensions
Although they are called cubes, OLAP databases can have more than three
dimensions. In fact, most cubes have three to eight dimensions. To understand
the concept of OLAP cubes, start with a simple data analysis model and then
expand it.
The key concept of online analytical processing (OLAP) is that of a cube. In this
document, we use the term cube to refer to any analytic data store. An OLAP cube
is a collection of related data—a database—that has multiple dimensions. The
term cube dimensions roughly describes the equivalent of fields in a relational
database. In terms of data analysis, dimensions can be thought of as criteria—such
as time, account, and salesperson—that can pinpoint a particular piece of data.
These pieces of data are usually transactions from an online transaction processing
(OLTP) system.

Although they are called cubes, OLAP databases can have more than three
dimensions. In fact, most cubes have three to eight dimensions. To understand the
concept of OLAP cubes, start with a simple data analysis model and then expand
it.

Suppose you want to analyze unit sales of your company. You can examine the
total units that were sold in a particular year, but that number might not help you
understand much about your business. Instead, you might want to see unit sales
broken down by time and by product. The matrix that you use to analyze this data
might look like the following table, which represents a cube with two dimensions
(time and product).

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