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Best Tips & Tricks for ETL Testing

ETL (Extraction, Transforming, and Loading) is the process of taking all of the data from various sources, transforming them into a compatible and consistent format, and loading it into the data warehouse. This process is fraught with challenges, so testing is crucial to assure that the daily loading of critical business information is properly stored for later analysis and retrieval. Here are the challenges associated with ETL, along with some valuable tips for making your ETL testing an inevitable success.

The Common Challenges Encountered During ETL Testing

Good data transfer leads to great business intelligence, which leads to stellar profits.

Challenges come in many forms: sometimes the business’ policies and procedures hinder the ETL process or the data itself does. These challenges can be identified and overcome through thorough testing.

  • Testing should identify any incompatible data from different sources, as well as duplicate data that needs to be eliminated.
  • Testing should identify any data loss incurred during the ETL process.
  • Persons responsible for ETL testing need to have the privileges to execute ETL jobs.
  • Testing should verify that the process can handle the volume of data to be transferred, as well as the complexity of that data.
  • Testing should identify any problems within the business processes and procedures that lead to inadequate data production, duplication of data, or missing critical data.
  • Persons testing should be able to build or acquire enough test data to make the testing procedure thorough and accurate, as well as indicative of how the ETL procedure will progress with actual business data.

Knowing these challenges ahead of time should help you build an adequate testing session that will verify that real ETL processes will progress without a hitch.

How to Verify a Successful ETL Testing Session


Once the ETL process is perfected, you can transfer data with confidence, and the business can bank on decisions made with the data.

Each process of ETL has the potential for problems. Here is what you should verify during the testing session:

  • Did the transfer of data from the source to its destination (generally the data warehouse) go as planned?
  • Did the data you expect to end up in the target destination (data warehouse) get there?
  • Are all the database fields and field data loaded? Was there any truncation of the data?
  • Does the checksum data for the record count match up between the source and the destination?
  • Was any rejected data properly logged? Do the logs contain adequate details about the issues?
  • Have all of the NULL value fields been verified?
  • Have any duplicate data sets been loaded?
  • Can you verify the integrity of the transferred data?

The New Rules for Your Data Landscape

It’s critical to work all of the kinks out of the process during testing so that you can have confidence in the transferred data used to create valuable business intelligence. In other words, test until the test sessions run perfectly before attempting to proceed with the actual ETL process.

Make sure to download our eBook, “The New Rules for Your Data Landscape“, and take a look at the rules that are transforming the relationship between business and IT.

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