Data engineering·Governance, privacy and meaning
two companies join their customer lists to measure overlap, and neither ever sees a row from the other side.
Data clean room
Also calledclean room, privacy-preserving join
A controlled environment where two parties can compute over combined data without either seeing the other's raw records, usually with minimum aggregation thresholds enforced. It exists because the useful question — did the people who saw our advertisement buy anything — needs both datasets and neither party may share theirs. The controls that matter are the query restrictions and the minimum group size, since without them a series of narrow queries reconstructs individual rows.