What is Cloud Spanner?
Why Interviewers Ask This
Interviewers use this question to quickly assess whether a candidate has the foundational knowledge required for Google Cloud Platform (GCP) development. It reveals whether you understand the building blocks that more complex concepts rely on.
Answer
Cloud Spanner is Google's globally distributed, strongly consistent, horizontally scalable relational database. It is unique in combining ACID transactions with horizontal scaling across regions — a combination previously considered impossible (the "CAP theorem trade-off"). Key features: True horizontal scaling: add nodes to increase throughput without downtime. Global strong consistency: reads anywhere see the latest committed data. Standard SQL: ANSI SQL 2011 compatible. 99.999% SLA (five nines) for multi-region configurations. Automatic sharding: data is split (sharded) across nodes automatically. Use cases: financial systems, global inventory, games leaderboards — any application requiring a relational database that needs to scale beyond what a single instance can handle. It is significantly more expensive than Cloud SQL, justified only for global-scale workloads.
Common Mistake
Don't just define the term — demonstrate that you understand when to use it and when not to. Showing awareness of trade-offs is what separates average from strong Google Cloud Platform (GCP) candidates.