What is a Data Warehouse?

Think of yourself as a data analyst working for a company that has the following three departments: Marketing, Sales and Finance. Now, let’s assume that each department maintains a separate database.

This could lead to a situation wherein each department has its own version of the facts. For a question such as ‘What is the total revenue of the last quarter?’, every department might have a different answer. This is because each department draws information from a different database.

This is where a data warehouse can prove to be useful. It can help with creating a single version of the truth and the facts. A data warehouse would thus be the central repository of data of the entire enterprise.

Now, in the upcoming video, you will learn what a data warehouse is and how it is useful for companies in carrying out data analytics. You will also learn about OLAP, which stands for Online Analytical Processing systems. OLAP is used to extract business-relevant information and perform analysis on the data stored in data warehouses. In the next video, you will understand the data warehouse.

So, a data warehouse is a collection of data. It has the following properties:

  • Subject-oriented: A data warehouse should contain information about a few well-defined subjects rather than the enterprise.
  • Integrated: A data warehouse is an integrated repository of data. It contains information from various systems within an organisation.
  • Non-volatile: The data values in a database cannot be changed without a valid reason.
  • Time-variant: A data warehouse contains historical data for analysis.

In the next segment, you will learn about the structure of the data warehouse.

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