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Thursday, 2 August 2018

ETL vs Database Testing

ETL vs Database Testing


Both ETL testing and database testing involve data validation, but they are not the same. ETL testing is normally performed on data in a data warehouse system, whereas database testing is commonly performed on transactional systems where the data comes from different applications into the transactional database.
Here, we have highlighted the major differences between ETL testing and Database testing.

ETL Testing

ETL testing involves the following operations −
  • Validation of data movement from the source to the target system.
  • Verification of data count in the source and the target system.
  • Verifying data extraction, transformation as per requirement and expectation.
  • Verifying if table relations – joins and keys – are preserved during the transformation.
Common ETL testing tools include QuerySurge, Informatica, etc.

Database Testing

Database testing stresses more on data accuracy, correctness of data and valid values. It involves the following operations −
  • Verifying if primary and foreign keys are maintained.
  • Verifying if the columns in a table have valid data values.
  • Verifying data accuracy in columns. Example − Number of months column shouldn’t have a value greater than 12.
  • Verifying missing data in columns. Check if there are null columns which actually should have a valid value.
Common database testing tools include Selenium, QTP, etc.
The following table captures the key features of Database and ETL testing and their comparison −
FunctionDatabase TestingETL Testing
Primary GoalData validation and IntegrationData Extraction, Transform and Loading for BI Reporting
Applicable SystemTransactional system where business flow occursSystem containing historical data and not in business flow environment
Common toolsQTP, Selenium, etc.QuerySurge, Informatica, etc.
Business NeedIt is used to integrate data from multiple applications, Severe impact.It is used for Analytical Reporting, information and forecasting.
ModelingER methodMultidimensional
Database TypeIt is normally used in OLTP systemsIt is applied to OLAP systems
Data TypeNormalized data with more joinsDe-normalized data with less joins, more indexes, and aggregations.