Lecture 14: Optimistic Concurrency Control

The podcast delves into FARMSTAY, a research prototype exploring high-speed networking hardware, and its use of Optimistic Concurrency Control (OCC). FARM achieves impressive transaction speeds—58 microseconds compared to Spanner's 10 milliseconds—by focusing on CPU time and network bottlenecks within a single data center, rather than geographic replication. Key performance enhancements include sharding, storing data in RAM, non-volatile RAM (NVRAM) via battery-backed solid-state drives, and RDMA (Remote Direct Memory Access) for efficient network communication. The discussion covers kernel bypass, where applications directly access network interface cards, and one-sided RDMA, enabling direct memory reads and writes. FARM uses OCC to manage transactions, employing a lock phase and validation stage to ensure serializability.