A payments platform needs a single SQL database that accepts writes in several continents at once. Every transaction must be atomic and strongly consistent, and the system must keep serving if an entire region fails. Which option should you choose?
Show answer and explanation
Answer: A
Cloud Spanner is a globally distributed relational database that offers ACID transactions and external consistency across regions. A multi-region configuration replicates data across regions while keeping writes consistent, and it survives the loss of a region. It is the right choice when transactional correctness must hold across geographies, not just for reads.
Why the other options are wrong
- B. Cloud Bigtable is a wide-column NoSQL store. It provides row-level atomicity only, not multi-row ACID transactions with SQL semantics, so it cannot enforce the cross-region transactional guarantees the platform requires.
- C. Cloud SQL read replicas copy data from a single primary, and writes still go through that one primary. Cross-region replicas replicate asynchronously, so a regional failover can lose recent commits.
- D. Memorystore is an in-memory cache, not an authoritative transactional database. Persistence options do not create multi-region ACID transactions or SQL semantics for ledger data.