What is ETL?
Extract, Transform & Load is a process in Data Warehousing. ETL refers to,
– Extraction of data from different applications – developed & supported by different vendors, managed & operated by different persons hosted on different technologies – into Staging tables
-Transform data from staging tables by applying a series of rules or functions – which may include Joining and Deduplication of data, filter and sort the data using specific attributes, Transposing data, make &business calculations etc – to derive the data for loading into the destination system
-Loading the data into the destination system, usually the data warehouse, which could further be used for business intelligence & reporting purposes
Why ETL Testing?
Accuracy of the data from the ETL process is critical as this underlying information influences business decisions & thereby its efficacy. ETL Testing aims to deliver complete, repeatable & auditable test coverage of the ETL process.
What needs to be Tested?
Each major step of ETL process needs to be verified to uncover data losses, transformation errors, output inaccuracies, data integrity issues, table balancing mismatches, application upgrade errors etc. Following areas are targeted for ETL testing,
- Data Completeness: Coverage for truncation, null records, special cases & boundary cases. Validating all records, fields, full contents are loaded. Verifying for checksum, record counts & analyzing data rejections.
- Transformation Rules: Verifying that the underlying data complies with Transformation & Business rules.
- Systems Integration
What are the career opportunities?
ETL Testing / Data Warehouse Testing though is a niche area within the Software Quality industry it has gained much prominence in the recent years. Currently, 15000 ETL Testing job positions are open for this exciting career pan India.
Manual Testers / QA Analyst
ETL / DWH / DB developers