The disclosure is directed to optimizing data writes in a distributed computing system, e.g., a social networking application. The system employs a write-ahead log (WAL) and a hybrid logical clock (HLC) together to improve data writes across data centers in the distributed computing system, including improving: (1) consensus monitoring and enforcement in replicating data across the data centers; (2) scalability of data writes, e.g., so that different data centers can together handle a sudden increase in data writes during specified periods and consistently maintain the time ordering of the data writes; (3) replication configuration of data centers so that client devices can specify a replication hierarchy per transaction, e.g., at the time of writing the data, rather than specifying at data center configuration time; and (4) a draining process to write transactions committed to the WAL to data storage systems in the data centers.