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8 Tips to Becoming a Great ETL Tester

ETL testing is a crucial part of an ETL project. It’s important to get it right and avoid making mistakes that disrupt your team’s progress. In this article, we’ll cover eight tips that will help you become a better ETL tester:

1. Understand the meaning of ETL testing.

Understand the meaning of ETL testing

You should know that ETL testing is all about testing the process of extracting and transforming data. It’s a subset of data quality, integration, and migration testing.

Data quality testing ensures no defects in the source system and will provide accurate results. Data integration testing checks whether the new system integrates well with other systems, such as an existing database or ERP software. 

Data migration is moving data from one location to another while preserving its integrity; it’s used when migrating from legacy systems to more modern ones (like SQL Server). ETL stands for Extract Transform Load – this refers to three different phases, which involve creating platforms where data can be transferred between two locations: source system & target system (for example, moving from Oracle database into MS SQL Server).

2. Learn how to write SQL queries.

SQL, or Structured Query Language, is a programming language used to interact with databases. It consists of keywords and statements written to retrieve information from a database and manipulate it according to your needs. Learning to write SQL queries is the most important thing you can do as an ETL tester.

SQL contains three main types of clauses: Data Definition Language (DDL), Data Manipulation Language (DML), and Transaction Control Language (TCL). DDL is used for creating tables and indexes; DML is for inserting, updating, and deleting records from tables; TCL allows users to control transactions within their programs.

3. Be aware of the basics of ETL processes

Be aware of the basics of ETL processes

ETL stands for extract, transform, and load. It is a process that moves all data from one system to another. The most common types of ETL processes are:

  • Data cleaning/cleansing: This includes resolving duplicate records in a database and ensuring they’re entered correctly (e.g., addresses match postal codes).
  • Data integration: Bringing data from different sources into one database gathered by converting incompatible formats or structures (e.g., JSON files versus Microsoft Excel spreadsheets).
  • Data extraction (or extraction-transformation-loading): Pulling information out of an existing database without making any changes; this process can also include formatting or changing how the data looks within its current structure (e.g., normalizing it).
  • Data transformation: Modifying a single record’s shape or content based on criteria such as date range or zip code; transformations may not apply across all records but only specific ones selected by business rules known as “ETL rules.”

4. Know data types and data structure rules.

Know data types and data structure rules

When writing ETL scripts, you must know what data types are available in your source systems. For example, if you’re working with Oracle and SQL server databases, then different data types can be used for columns in each database. In Java, you may have to deal with file formats or object types with unique rules for handling certain values.

Learn to identify data type errors when testing ETLs based on those rules. When testing ETLs based on sources like SQL databases or files from text editors such as Notepad++ or Sublime Text 3., it’s important that we know what kind of information goes where so we can identify errors quickly rather than spending hours on end trying out different combinations until we finally get one right (which often happens more often than not).

5. Consider other important aspects.

The following list is the most important aspects to consider when becoming a great ETL tester:

  • Understand the different types of ETL testing tools
  • Understand the different types of ETL testing methodologies
  • Understand the different types of ETL testing phases

6. Get a better understanding of ETL data testing discrepancies.

Get a better understanding of ETL data testing discrepancies

To become a great ETL tester, you need to know what ETL data testing discrepancies are. One of the best ways to gain this knowledge is by understanding what types of errors can occur during ETL and how they might be detected.

There are many different types of discrepancies that may occur during any given migration or changeover process, including:

  • Data type mismatches
  • Inconsistent field lengths across tables
  • Missing values in certain fields

7. Learn about different types of Database Testing

Database testing is a highly specialized skill that requires a lot of practice and experience. There are many ways to do database testing, including manual and automated testing. Manual database testers perform their tasks manually by going through each step of the process one by one. Automated database testers use software programs to execute tests on databases automatically.

To become an expert at database testing, you’ll need to know how these different methods work and what their pros and cons are:

8. Be aware of all hands-on roles in an ETL organization.

Be aware of all hands-on roles in an ETL organization

Knowing the different types of ETL roles is important; it will help you understand what you should do to get a job. There are many different roles in an ETL organization, but they all fall under two categories: hands-on and management. The hands-on roles include process engineers, data analysts, data engineers, and quality assurance specialists. Management includes project managers, directors of engineering, and management lifecycle experts. These roles are important because they all have a hand in the ETL process.


ETL testing is a challenging job that requires a lot of dedication and hard work. But once you become an ETL tester, you will be able to enjoy the many benefits of this career path. The knowledge you gain through this process will help you advance your career or even start your own business someday! So keep on learning and practicing until you get there. We hope that these tips will help you become a great ETL tester. If you follow them, you’ll be well on your way to joining the elite ranks of the data testing community!

2022-12-14T13:20:47+00:00December 14th, 2022|

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