ETL Testing Interview Questions And Answers

 Below you can find a few questions and answers which are more frequently asked in the ETL testing interviews:

Q #1) What is ETL?

Answer: ETL refers to Extracting, Transforming and Loading of Data from any outside system to the required place. These are the basic 3 steps in the Data Integration process. Extracting means locating the Data and removing from the source file, transforming is the process of transporting it to the required target file and Loading the file in the target system in the format applicable.

Q #2) Why ETL testing is required?

Answer: ETL testing is required

• To keep a check on the data which are being transferred from one system to the other.
• To keep track on the efficiency and speed of the process.
• To be well acquainted with the ETL process before it gets implemented into your business and production.

Q #3) What are ETL tester responsibilities?

Answer: Responsibilities include

• Requires in-depth knowledge of the ETL tools and processes.
• Needs to write the SQL queries for the various given scenarios during the testing phase.
• Should be able to carry our different types of tests such as Primary Key, defaults and keep a check on the other functionality of the ETL process.
• Quality Check

Q #4) What are Dimensions?

Answer: Dimensions are the groups or categories through which the summarized data are sorted.

Q #5)  What is the Staging area referring to?

Answer: The Staging Area is the place where the data is stored temporarily in the process of Data Integration. Here, the data s cleansed and checked for any duplication.

Q #6) Explain ETL Mapping Sheets.

Answer: ETL mapping sheets contain all the required information from the source file including all the rows and columns. This sheet helps the experts in writing the SQL queries for the ETL tools testing.

Q #7) Mention a few test cases and explain them.

Answer:

• Mapping Doc Validation – Verifying if the ETL information is provided in the Mapping Doc.
• Data Check – Every aspect regarding the Data such as Data check, Number Check, Null check are tested in this case
• Correctness Issues – Misspelled Data, Inaccurate data and null data are tested.

Q #8) List a few ETL bugs.

Answer: Calculation Bug, User Interface Bug, Source Bugs, Load condition bug, ECP related bug.

In addition to the above ETL testing questions, there may be other vital questions where you may be asked to mention the ETL tools which you have used earlier. Also, you might be asked about any debugging issues you have faced in your earlier experience or about any real-time experience.