ETL Testing Interview Questions and Answers
Extract/Transform/Load, shortly the ETL is a tool that extracts data from the source systems, transforms them into a consistent data type, then loads it into a data warehouse. The ETL testing process verifies whether the complete ETL process is working with its full potential. If you are searching for ETL testing questions and answers for experienced or freshers, we will discuss them for you here further.
The ETL testing is highly required to maintain an excellent confidence level among end-users in the data stored in the data warehouse. As ETL process has some tests, it needs different types of ETL testing procedures, such as accuracy testing, data validation testing, completeness testing, metadata testing, software testing, reference testing, syntax testing, interface testing, and performance testing
Most Frequently Asked ETL Testing Interview Questions
ETL testing’s cosmetic bug is related to the GUI of an application. This bug can be related to font size, font style, alignment, colors, navigation, spelling mistakes, etc.
In ETL, the Database Normalization is a process required to organize the tables and attributes of a relational database to minimize data redundancy. The process involves decomposing a table into less redundant tables without losing any information.
In ETL, cubes are data processing units which contain dimensions and fact tables from the data warehouse and provide multi-dimensional analysis. OLAP or Online Analytics Processing stores large data in a multi-dimensional form for reporting purpose. The OLAP cubes consist facts called as measures categorized by dimensions.
The logical structures where the database stores the schema object logically within a database tablespace are defined as schema objects. These objects can be table, views, indexes, database links and function packages.
A fact-less fact table doesn’t consist of any measures. It’s an intersection of dimensions.
It has two types.
- To capture an event
- To describe conditions
A lookup transformation allows users to access data from relational tables that are not defined in mapping documents. It enables users to update slowly changing dimension tables to determine whether the records already exist in the target or not.
Following is a set of most frequently asked ETL testing interview questions which should be must be acknowledged by ETL tester and developers for future interview success.
Advantages
- Increases productivity for IT developers. It’s less time consuming, and resource required also.
- Lower business risk and higher confidence level in the data can be achieved with comprehensive ETL testing
- The informatics data validation offers visibility and automation for ETL testing, to ensure that tested data delivered in production system updates.