A payments platform needs a relational schema with multi-row ACID transactions, SQL access and strongly consistent reads. It must also keep synchronous replicas on three continents so the service survives a regional outage. Which storage service fits?
Show answer and explanation
Answer: D
Cloud Spanner is a horizontally scalable relational database that supports SQL, ACID transactions across rows and tables, and strongly consistent reads. Multi-region configurations replicate data synchronously across regions, including regions on different continents, which lets the platform survive a regional outage. Cloud SQL is a regional managed service and does not provide that global synchronous replication. Bigtable is a wide-column NoSQL store without multi-row relational transactions.
Why the other options are wrong
- A. Bigtable is a wide-column NoSQL store with single-row atomicity, not multi-row relational transactions. It also lacks SQL joins, so it does not satisfy the schema and transaction requirements.
- B. Cloud SQL is a managed relational service with transactions, but a single-region instance does not replicate synchronously across continents. It cannot meet the global availability requirement.
- C. Firestore in Datastore mode is a document database with a different query model and no relational schema. It does not provide the SQL joins and relational structure the platform needs.