Lakehouse

A table format layered over object storage so that a lake behaves like a warehouse: atomic commits, snapshot isolation, schema enforcement and time travel over plain Parquet files. It exists because the two-system arrangement — lake for raw, warehouse for modelled — meant every table was copied, and the copy was the thing that drifted. The remaining trade is maturity: the metadata layer is now a component you operate, and small-file and compaction management is your job rather than the vendor's.