Es una base de datos relacional.

Es multiregion

Soporta transacciones ACID.

Alta disponibilidad global.

TrueTime es un sistema desarrollado por Google para sincronizar los relojes en todas las máquinas de sus data centers (centros de datos) a nivel global. Esto es fundamental para lograr la consistencia global en Cloud Spanner.

Strong reads - used when the absolute latest value needs to be read

Stale reads are used when low read latency is more important than getting the latest values, so some data staleness is tolerated. In a stale read, the client does not request the absolute latest version, just the data that is most recent (e.g. up to n seconds old). If the staleness factor is at least 15 seconds, the replica in most cases can simply return the data without even querying the leader as its internal state will show that the data is sufficiently up-to-date. You can see that in each of these read requests, no row locking was required - the ability for any node to respond to reads is what makes Cloud Spanner so fast and scalable.

Split replicas are associated with a group (Paxos) that spans zones. Using Paxos consensus protocols, one of the zones is determined to be a leader. The leader is responsible for managing write transactions for that split, while the other replicas can be used for reads. If a leader fails, the consensus is redetermined and a new leader may be chosen.