Comparison
Medallion architecturevsStaging layer
Medallion architecture
the same data exists three times: exactly as it arrived, cleaned and typed, and shaped for a specific report.
Layering a lakehouse into raw arrivals, cleaned and conformed tables, and business-level aggregates. The value is that each layer has one job and one class of failure, so a bad number can be traced by walking down the layers, and reprocessing can start from any of them. The failure mode is ceremony — three copies of a table that only ever gets renamed — which is why the middle layer has to actually do conforming rather than just casting.
Full entry →Staging layer
the supplier renamed a column overnight and you fixed it in one place instead of in forty downstream queries.
A thin layer between the raw arrival and any real logic, where names, types and light cleaning are standardised and nothing else happens. Its job is to be the single place a source's oddities are absorbed, so a supplier renaming a column is one edit rather than forty. Skipping it feels faster for the first month and is the reason mature warehouses have the source's naming conventions leaking into business models.
Full entry →