How do ETL and ELT differ in where transformation occurs?

How do ETL and ELT differ in where transformation occurs?

• A. ETL loads data with cleansing and transformation before loading into the target; ELT loads raw data and then transforms inside the target system.
• B. ETL uses machine learning; ELT uses manual SQL only.
• C. ETL is used only for small datasets; ELT is for large datasets.
• D. ETL loads data without transformation; ELT applies transformations before loading.

Answer: (A)

The main idea is where the data transformation happens in the flow. In ETL, you cleanse and transform the data during the extraction/transform phase before it’s loaded into the target system, so the target receives already processed data. In ELT, you first load the raw data into the target, and then perform the transformations inside the target system using its processing capabilities. This distinction is precisely what choice describes: transformation before loading for ETL, and loading raw data followed by in-target transformation for ELT. The other statements don’t capture this difference. One mentions machine learning versus manual SQL, which isn’t what defines ETL versus ELT. Another suggests the method depends on dataset size, which isn’t the core distinction. The last implies ETL does no transformation, which contradicts ETL’s purpose.

The main idea is where the data transformation happens in the flow. In ETL, you cleanse and transform the data during the extraction/transform phase before it’s loaded into the target system, so the target receives already processed data. In ELT, you first load the raw data into the target, and then perform the transformations inside the target system using its processing capabilities. This distinction is precisely what choice describes: transformation before loading for ETL, and loading raw data followed by in-target transformation for ELT.

The other statements don’t capture this difference. One mentions machine learning versus manual SQL, which isn’t what defines ETL versus ELT. Another suggests the method depends on dataset size, which isn’t the core distinction. The last implies ETL does no transformation, which contradicts ETL’s purpose.