Concurrency control ensures the correctness of databases when transactions are processed in parallel. Bamboo is a state-of-the-art concurrency control protocol. One problem of Bamboo is that it requires transactions to fetch timestamps from a single centralized atomic counter. To replace the concentrated access to it, each transaction should generate timestamps independently. This paper proposes two methods of decentralization to address the problem. The first is the thread-ID method (TID): transactions use thread IDs as their timestamps. In high-contention settings, the performance of TID plummets, but proposed optimization FairTID sustains the performance. The second method (RandID) allocates timestamps using random-number generators. Experiments indicated that there were up to 60% and 34% improvement in throughput from Bamboo with FairTID and RandID, respectively. In high-contention settings, TID recorded 24% degradation, but FairTID and RandID showed 19% to 31% and 12% to 22% improvement from Bamboo, respectively.