In an ETL process, what is the Transform stage?

• A. Convert extracted data into a form that can be placed into another database
• B. Extract data from source systems
• C. Write transformed data directly to the data warehouse
• D. Analyze data to determine business insights

Answer: (A)

The Transform stage is about converting extracted data into a form that can be placed into the target database, including cleansing, standardizing data formats (like dates and currencies), handling missing values, deduplicating, deriving new fields, and sometimes aggregating data. This shaping makes data from different sources consistent and ready for loading into the data warehouse. It’s different from extraction, which pulls data from sources, and from loading, which writes the transformed data into the warehouse. It also isn’t about analyzing for insights, which happens after the data is stored and used for reporting.