TrueTime measures a point in time plus/minus an error interval. The API allows a program to query for when a time/error pair has definitely passed. Each transac

TrueTime measures a point in time plus/minus an error interval. The API allows a program to query for when a time/error pair has definitely passed. Each transaction acquires locks using 2-phase locking. At commit time, the time/error are read and the decision to commit is stored durably using Paxos. The locks are then held until the time of the transaction has definitely passed. This guarantees that no process which grabs the locks after they are released can commit at an earlier time than previous holders of the lock.