Your company is evaluating Google Cloud database options for a mission-critical global payments gateway application. The application must be available 24/7 to users worldwide, horizontally scalable, and support open source databases. You need to select an automatically shardable, fully managed database with 99.999% availability and strong transactional consistency. What should you do?

Cloud Spanner is the only Google Cloud database that meets all the specified requirements. It is a fully managed, globally distributed relational database service designed for mission-critical applications. It provides horizontal scalability for both reads and writes, automatic sharding (splits), and guarantees strong transactional consistency (ACID compliance) across regions. Critically, for a global payments gateway, Cloud Spanner offers a 99.999% availability Service Level Agreement (SLA) for multi-region configurations, making it the ideal choice for this use case.

A. Select Bare Metal Solution for Oracle. This is a solution for migrating existing proprietary Oracle workloads, not a cloud-native, fully managed, or open-source compatible service. It does not offer built-in global distribution.
B. Select Cloud SQL. Cloud SQL is a regional service and does not offer the 99.999% availability SLA required. It scales vertically for writes and lacks automatic sharding for horizontal scalability.
C. Select Bigtable. Bigtable is a NoSQL wide-column store that does not support the multi-row, strongly consistent ACID transactions essential for a financial payments gateway application. ---

1. Cloud Spanner Documentation - "What is Cloud Spanner?": "Cloud Spanner is a fully managed relational database with unlimited scale, strong consistency, and up to 99.999% availability... Spanner is a good choice for any application that requires strong transactional consistency, high availability, and horizontal scalability." This directly supports the choice of Spanner for the described workload.

Source: Google Cloud Documentation, "What is Cloud Spanner?", Introduction section.

2. Google Cloud Service Level Agreements (SLAs) - Cloud Spanner SLA: This official document specifies the availability guarantees. "For a Multi-Region instance configuration, the Monthly Uptime Percentage is ≥99.999%." This confirms Spanner meets the stringent availability requirement.

Source: Google Cloud Legal, "Cloud Spanner Service Level Agreement (SLA)", Section: Service Levels.

3. Google Cloud Documentation - Cloud SQL Overview: "Cloud SQL is a fully managed relational database service... Cloud SQL instances provide a 99.99% availability SLA for a high availability configuration." This shows Cloud SQL does not meet the 99.999% SLA and is positioned as a regional service.

Source: Google Cloud Documentation, "Cloud SQL instances", High availability configuration section.

4. Google Cloud Documentation - Bigtable - "Transactions and schema design": "Bigtable does not support transactions that affect multiple rows... If you need ACID compliance for complex transactions, consider Spanner." This explicitly disqualifies Bigtable due to the lack of strong transactional consistency needed for a payments system.

Source: Google Cloud Documentation, "Bigtable - Transactions and schema design", Transactions section.