Today, distributed databases lead the market, but time synchronization in distributed systems remains a hard nut to crack. Due to the clock skew, the time in different nodes of a distributed database cannot be synchronized perfectly. Many computer scientists have proposed solutions such as the logic clock by Leslie Lamport (the 2013 Turing Award winner), the hybrid logical clock, and TrueTime.
PingCAP’s TiDB, an open-source distributed NewSQL database, adopts timestamp oracle (TSO) to deliver the time service and uses a centralized control service — Placement Driver (PD) — to allocate the monotonically increasing timestamps.