Database

An in-memory database keeps the working set in RAM for sub-millisecond reads/writes, typically adding durability via logs/snapshots and HA via replication/sharding.

Spanner is Google's globally distributed database that provides externally consistent reads and writes — the first system to achieve global ACID transactions at scale using TrueTime and Paxos.

Concurrency control mechanism that assumes conflicts are rare and handles them when they occur, using version numbers or timestamps to detect concurrent modifications