An online system performs replication of database from one system to another. A source database is replicated to a target database by performing an initial bulk copy followed by repeated change data capture. The system performs batching to group events generated by the change data capture events. The system performs a multi-constrained analysis to determine when a batch is ready for sending. The system uses multiple buffers for transmitting events to decouple the receiving and sending of events. The online system may be a multi-tenant system the source and target databases stores data of tenants. The system determines a tenant score to adjust the resources allocated during event transfer. The system splits an event into partial events, to avoid dependency between the partial events so that tasks can be executed independent of each other. Therefore, the system performs replication with reduced synchronization overhead.