Today let me take a moment and explain my testing fraternity about one of the much in demand and upcoming skills for my tester friends i.e. ETL testing (Extract, Transform, and Load). This article will present you with a complete idea about ETL testing and what we do to test ETL process.
It has been observed that Independent Verification and Validation is gaining huge market potential and many companies are now seeing this as prospective business gain. Customers have been offered different range of products in terms of service offerings, distributed in many areas based on technology, process and solutions. ETL or data warehouse is one of the offerings which are developing rapidly and successfully.
Why do organizations need Data Warehouse?
Most of the companies are taking a step forward for constructing their data warehouse to store and monitor real time data as well as historical data. Crafting an efficient data warehouse is not an easy job. Many organizations have distributed departments with different applications running on distributed technology. ETL tool is employed in order to make a flawless integration between different data sources from different departments. ETL tool will work as an integrator, extracting data from different sources; transforming it in preferred format based on the business transformation rules and loading it in cohesive DB known are Data Warehouse.
Well planned, well defined and effective testing scope guarantees smooth conversion of the project to the production. A business gains the real buoyancy once the ETL processes are verified and validated by independent group of experts to make sure that data warehouse is concrete and robust.
ETL or Data warehouse testing is categorized into four different engagements irrespective of technology or ETL tools used:
ETL Testing Techniques:
1) Verify that data is transformed correctly according to various business requirements and rules.
Apart from these 4 main ETL testing methods other testing methods like integration testing and user acceptance testing is also carried out to make sure everything is smooth and reliable.
ETL Testing Process:
Similar to any other testing that lies under Independent Verification and Validation, ETL also go through the same phase.
It is necessary to define test strategy which should be mutually accepted by stakeholders before starting actual testing. A well defined test strategy will make sure that correct approach has been followed meeting the testing aspiration. ETL testing might require writing SQL statements extensively by testing team or may be tailoring the SQL provided by development team. In any case testing team must be aware of the results they are trying to get using those SQL statements.
Difference between Database and Data Warehouse Testing
There are number of universal verifications that have to be carried out for any kind of data warehouse testing. Below is the list of objects that are treated as essential for validation in ETL testing:
ETL Testing Challenges:
ETL testing is quite different from conventional testing. There are many challenges we faced while performing data warehouse testing. Here is the list of few ETL testing challenges I experienced on my project:
Data is important for businesses to make the critical business decisions. ETL testing plays a significant role validating and ensuring that the business information is exact, consistent and reliable. Also, it minimizes hazard of data loss in production.
Hope these tips will help ensure your ETL process is accurate and the data warehouse build by this is a competitive advantage for your business.
This is a guest post by Vishal Chhaperia who is working in a MNC on a test management role. He is having extensive experience in managing multi technology QA projects, Processes and teams.
Have you worked on ETL testing? Please share your ETL/DW testing tips and challenges below.