Extract, Load, Transform (ELT)

Technical explanation

ELT uses the storage and compute capabilities of a cloud warehouse or lakehouse to preserve raw or lightly processed data and transform it into curated models. Modern implementations use versioned transformation code, tests, lineage, orchestration, and controlled access to raw layers.

Business relevance

ELT can accelerate ingestion, retain source detail, and support flexible analytical modelling without maintaining a separate transformation platform.

Implementation example

A company loads raw advertising and sales data into a cloud warehouse, then runs tested SQL models to produce campaign-attribution and revenue tables.

Limitations and common misconceptions

Loading first can expose sensitive or low-quality data inside the target. Compute costs, duplicated transformations, weak layer design, and uncontrolled access can offset the flexibility of ELT.

Topics

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