Introduction to ETL Testing
ETL Testing is performed during the ETL phase, which includes verification and validation of the process of Extracting the data from multiple data sources, transforming all the data to a single common format and loading the formatted data to the destination. ETL Testing is executed through various stages like any other type of Testing. The Testing stages are ‘detecting the data sources and analyzing the requirements’, ‘fetching the data and designing the ETL flow’, ‘enforcing the finalized design and database representation’, ‘construction of database/ table and placement of data’, and finally ‘generation of analytical results and reports’ as per the requirement specification.
Understanding What is ETL Testing?
Extract means to fetch the data from any transactional system or any other RDBMS like Oracle, Microsoft, and several others. The data present in this stage are unstructured and is a huge lump of data with no meaning.
Transform means to sort data or filter out data with the help of operations that are suitable as per the circumstances.
Load means transforming data by moving it to a central repository or to an OLAP data warehouse.
How does ETL work so Easy?
Let’s take a real-time scenario to explain how ETL works. We know data is everywhere no matter how smaller the organizations are. The data comes from these resources like staff, employees, work they do an organization’s business and several other ways. Since every organization wants to study how their business works and to do this the best way is to analyze past or historical data. Here comes the ETL concept at the rescue.
E.g. Let us take Organization A has several departments like sales, HR, Developments, business, etc. All of these departments have different databases. Now if Org A wants to analyze data and generate the report it has to extract the data and transform it into a warehouse to save it for the later stage of performing analytical work.
Later this data will be manipulated by BI tools to provide meaningful insights.
What can you do with ETL Testing?
This is a one-way process and mainly organizes itself for data extraction purposes only. Once the data is fetched out you can use any number of tools to manipulate it. We would like to inform our readers not to confuse yourself with data warehouse testing and database testing. The later concept deal in huge chunks of data compared to its predecessor.
Working with ETL
Working with ETL is not at all the stuff we want to say to our readers. An ETL tool has 3 layered architectures built into it.
These are –
- Staging Layer: In this layer, the data are accumulated in one place. The data may come from different sources or data systems.
- Data Integration Layer: This layer moves the data to the database which it receives from the staging layer. Here the data are sorted into hierarchical groups which are also known as dimensions and facts. A combination of facts and dimensions are known as Schema.
- Access Layer: This is mainly used by the end users to final retrieval of data for analytical reporting and information.
Advantages of ETL Testing
- Visual flow –All the ETL tools have this capability to show their users a visual flow of the process. This makes the migration process more transparent and a user gets to know what exactly is happening. They also generate Scripts IDE.
- Choice of programming code – All the ETL tools give their users to manipulate the work using most of the programming languages. These are used to write codes. You have to check the language compatibility of the ETL tool you are looking for.
- Module – Most of the ETL tools have a module wise categorization for the dashboard. Each module has a specific purpose. This gives a good user experience with interactive experience.
- Performance – The test modules give the work done in an efficient way in the least time possible.
- Easy understanding and maintenance – It has a click and drags functionality to achieve the most of the task to perform. Visual appearance gives a better understanding.
Required Skill
There is again no specific knowledge required to begin your career in ETL testing. We have listed some best to have practiced for our readers and fresher’s who are looking to build their career in ETL.
- Prefer to have a B.Tech degree in any stream (CSC and IT are preferred)
- Look to have a Master’s degree in a bachelor’s degree in computers.
- Database knowledge is a must to have and with saying this we would also like to say SQL server knowledge is also mandatory.
- Try to have an overview understanding of some BI tools like Tableau and Excel.
Why use ETL Testing?
To perform data warehouse testing and also for unit testing. To dig deep into our unorganized data. These data can be in multiple forms like spreadsheets to logs to code data
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Scope
To be very fare with our readers we would like to say that ETL is very crucial for any company but the scope depends upon the availability and also it is not a developer work so the demand will not be in that demand. With the arrival of new BI tools and new processes, there are alternate ways to dig deep into your dataset. These factors have influenced the scope of ETL testers and tools.
How this technology will help in career growth?
Experience and multiple skills knowledge is something we would recommend to our readers looking having ETL career. Please acquire more knowledge as it will be the best survival techniques in the IT world where things change with every passing date. Let us see some salary stats the industry is offering to its employees.
- Data Engineer – $66,228
- BI Intelligence – $52,381
- Senior Data Engineer – $78,000
Conclusion
There is a need for ETL testers and will always be, however, the concerns are the volume of jobs this technology generates. With the arrival of new technologies and a race to acquire the market by providing multiple features in one product. We want our readers to dig deep and check every possibility. We are only concerned about the volume of jobs in the market worldwide.
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