A distributed database system may include storage layer. The storage layer may partition data and store the partitioned data in a distributed database. The system may further include access layer. The access layer may receive a transaction, identify target data corresponding to the transaction, and generate a lock request to lock the target data included in the partitioned data. The system may further include lock service layer. The lock service layer may identify, based on the lock request, a lock status for the target data according to a lock record for the target data. The lock service layer may lock, in response to the lock status being in an unlocked state, the target data. The lock service layer may block, in response to the lock status being in a locked state, the lock request and store the lock request in a queue.