In this article, we will discuss the concept of Data Warehouse staging extracts in SQL Server. Staging extracts are an essential part of the Data Warehouse process, as they involve copying data from the source to the Data Warehouse staging area for further processing.

What are Data Warehouse Staging Extracts?

Data Warehouse staging extracts are processes that copy data from the source database to the Data Warehouse staging area. The staging area is a one-to-one mapping of data from the source to the destination, where data from multiple sources is stored to be processed further.

Benefits of Staging Area

The main benefit of the staging area is the independence it provides from the source once the data is extracted. This means that the Data Warehouse processing does not need to refer to the original source as long as its staging extract has been captured. This independence allows for more efficient and streamlined data processing in the Data Warehouse.

Importance of Staging Extract

The staging extract is a crucial part of the initial phase of Data Warehouse processing. It serves as the entrance to the Data Warehouse database and provides the necessary data for business intelligence needs. By ensuring the accuracy and reliability of the staging extract, we can ensure the overall quality of the Data Warehouse.

SQL Unit Testing Staging Extract

As staging extracts are a critical component of the Data Warehouse workflow, it is important to perform SQL unit testing on these extracts. SQL unit testing allows us to verify the functionality and correctness of the staging extract process.

When performing SQL unit testing on staging extracts, it is important to identify what needs to be unit tested and what can be excluded. We should focus on testing the source script, which is responsible for extracting data from the source database. By writing SQL unit tests against the source script, we can ensure that the staging extract process is working as expected.

Using tSQLt for SQL Unit Testing

tSQLt is a highly productive and acclaimed SQL unit testing framework that is well-suited for testing Data Warehouse staging extracts. It provides a purpose-built and feature-rich environment for writing and running SQL unit tests.

To perform SQL unit testing on staging extracts using tSQLt, we need to set up the framework and create the necessary test classes and procedures. By creating a test class specifically for staging extracts, we can focus on testing the functionality of the staging extract process.

Conclusion

Data Warehouse staging extracts play a crucial role in the overall Data Warehouse process. By performing SQL unit testing on these extracts using frameworks like tSQLt, we can ensure the accuracy and reliability of the staging extract process. This, in turn, contributes to the overall quality and effectiveness of the Data Warehouse.