Basic Concepts and Terminology

Objectives
After completing this lesson, you will be able to:

After completing this lesson, you will be able to:

  • Understand modeling terminology of SAP HANA Cloud so that you are ready to begin modeling

Key Concepts of Data Modeling

Before introducing calculation views in SAP HANA Cloud, you should become familiar with some key modeling concepts and the terminology that is frequently used.

Measure and Attribute

A data model usually contains a selection of measures and attributes.

Measure Versus Attribute

 MeasureAttribute
What is it?A numeric value, such as a price or quantity, on which you can process arithmetic or statistics operations, such as sum, average, top N values, and calculations.A descriptive element such as 'country' that is used the provide context for a measure. For example 'Sales Revenue by France'.
Examples
  • Quantity

  • Sales Revenue

  • Product

  • Customer

  • Country

  • Year

Attributes are used to filter or aggregate the measures, in order to answer questions such as the following:

  • What are the total sales originating from Hamburg?

  • What is the sales revenue for Cars in 2022?

Dimension

A dimension is a group of related attributes. In the example below, we see a dimension called Product. This dimension includes various related attributes including product name, category, supplier.

Dimensions are re-useable objects. When they have been created they can are shared by developers and used to develop star schemas.

Star Schema

A star schema is a very powerful type of data model that we can create in SAP HANA Cloud. A star schema invokes a powerful OLAP engine to provide fast slice-and-dice across data.

Watch this video to learn about the Star Schema.

Note
A fact table can be one table but it is often defined from a combination of tables to produce a view of a transaction, such as a sales order. Dimensions are then connected to the fact table to provide additional, descriptive information about the transaction, such as, the country of the customer.

Hierarchy

A hierarchy is a structured representation of an organization, a list of products, the time dimension, and so on, using levels.

It is often used to provide easy navigation of a large data set in a drill-down. You can define one or more hierarchies in calculation views that provide the end user with a convenient and natural way to navigate their data.

Watch this video to learn about the hierarchy concept.

Semantics

The term semantics is used to describe the meaning of an attribute or a measure. For example:

  • A monetary value

    For example, the total amount sold would need to indicate the currency (for example USD, EUR, or GBP). Amount without a currency is meaningless.

  • A quantity, weight, volume, or distance

    For example, quantity would need to specify the unit of measurement in which the data is expressed. Again, a quantity without a unit of measurement is meaningless.

In SAP HANA Cloud we can add semantics to measures, attributes or an entire calculation view. Semantic information is essential in the final report to provide the business user with important information about the data. This information is often not available in the original source tables but can easily be added by the developer in the calculation view.

Calculation Views in SAP HANA

A calculation view is the key modeling object of SAP HANA Cloud.

The purpose of calculation views is to project data from the individual database tables, and to perform a variety of data calculations in order to generate a meaningful result set to answer a specific business question.

Benefits of Calculation Views

Design-Time Versus Runtime Calculation Views

Deploying Calculation Views

When you deploy a design-time file with the Business Application Studio, SAP HANA Cloud generates the corresponding runtime object in a database container. A container is where all related run-time objects are stored in the database. An SAP HANA Cloud database can have many containers. We will cover containers later.

Analytical Versus Transactional Requirements

In transactional applications, such as SAP ERP, the underlying data (stored in physical tables) is generally handled by the application server. This layer is necessary to handle the business process logic. The application usually reads and writes directly to the database tables. Calculation views are not usually needed, however it is technically possible for the application to read a calculation view if this benefits the application. For example, it is possible to consume a calculation view from ABAP.

Calculation views are read only, and cannot change data in the SAP HANA Cloud database.

Analytical applications that do not usually need to write to the database so they can bypass the application server and directly query the calculation views, where data is calculated on-the-fly, in the SAP HANA Cloud in-memory database.

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