BigQuery Data Clean Rooms vs Spanner migration tool

BigQuery Data Clean Rooms let multiple parties share, join, and analyze data without moving or revealing the underlying data. The cloud service works with BigQuery sharing, and shared resources must be BigQuery tables, views, or table-valued functions. Owners manage rooms, contributors publish data, and subscribers query it. Contributors can apply analysis rules, including aggregation thresholds, and owners or publishers can offer predefined query templates without exposing the underlying tables or views. Subscribers are automatically prevented from copying or exporting raw data, while contributors can configure controls for query results. These controls have limits: Google cautions that analysis rules may not stop sophisticated queries from extracting unauthorized data, and notes that rules can be set only on views. Each room can contain at most 100 shared resources. Availability is restricted to BigQuery sharing regions, without listings across multiple regions. Rooms can be managed in the Google Cloud console or created through the API; setup requires enabling the Analytics Hub API and assigning required IAM roles. Contributors pay for storage, while subscribers pay for compute when running queries.

Spanner migration tool has no write-up on Specifiction yet; its figures are above.