Introduction To ETL
To begin with, ETL stands for extract, transform and load and it is a method of loading data from the source system to the data warehouse. In addition, it extracts data from the OLTP database and transforms it to match the data warehouse schema before loading it into the data warehouse database. It consists of three steps for integrating data from the source to the destination.
- Extraction- It extracts data from databases and legacy systems, cloud, hybrid, and on-premises environments, CRM systems data storage platforms, data warehouses, and many more.
- Transformation- The transforming process consists of cleansing, standardization, deduplication, verification, and sorting data.
- Loading- This step includes loading the newly transformed data into a new destination
What Is ETL Testing
ETL Testing is the process of checking the transportation of data from extraction to loading. Any errors in it could result in conveying poor information conveyed across the enterprise. Therefore, ETL testing helps in eliminating the chances of such errors along with the bugs in it. To further know about it, one can visit ETL Testing Training Institute in Gurgaon.
Stages Of ETL Testing
- Identify Business Requirements- The first stage includes designing the data model, defining the business flow, and assessing reporting needs according to client expectations. In addition, it helps in clearly defining, documenting, and understanding the scope of the project.
- Validate Data Sources- It includes performing a data count check and verifying that the table and column data type meets the specifications of the data model. In addition, it also helps in removing duplicate data and making sure that check keys are in place.
- Design test cases- It allows designing ETL mapping scenarios, creating SQL scripts, and defining transformational rules. In addition, it is necessary for validating the mapping document and ensuring that it contains all of the information.
- Extract data from source systems- This step executes the ETL tests per business requirements and identifies bugs or defects found during testing and reporting processes. After that, it includes fixing the bug and resolving and closing the bug report.
- Apply transformation logic- It transforms data for matching the schema of the target data warehouse. In addition, it is also helpful in checking data threshold, alignment, and validating data flow. Thus, results in matching the data type with the mapping document for each column and table.
- Load data into target warehouse- It performs a record count check before moving data from the staging to the data warehouse. Moreover, it helps in verifying that the invalid data is rejected and that the default values are accepted.
- Summary report- This step involves verifying the layout, options, filters, and export functionality of the summary report. In addition, this process provides details and results of the testing process to stakeholders and decision-makers. There are many ETL Testing Training Institute in Delhi and one can enroll in them to start a career in them.
Types Of ETL Testing
Given below are some of the types of ETL Testing
- Production Validation- It provides the ETL testing automation along with the management capabilities to support business decisions.
- Source to Target- They are useful in validating whether the data values transformed are the expected data values or not.
- Application Upgrades- It checks whether the data taken from an older application is the same as the data in the new application.
- Metadata Testing- This testing includes testing of data type, data length, and index/constraint.
- Data Completeness- It is done to ensure that the expected data is loaded in target from the source.
- Accuracy- It helps in verifying whether the data is accurately loaded and transformed as expected or not.
- Data Transformation- This testing helps in verifying the transformation rules and it requires running multiple SQL queries.
- Data Quality- They include syntax and reference tests and they are useful in avoiding any error due to date or order number.
- Incremental ETL- It checks the data integrity of old and new data with the addition of new data.
- GUI/Navigation- It is useful in checking the navigation or GUI aspects of the front-end reports.
Best ETL Testing Tools
Given below are some of the best ETL testing tools available in the market.
• BiG EVAL.
• Informatica Data Validation.
• Datagaps ETL Validator