Methods, apparatus and computer programs are provided for data replication, such as for replicating a database or updating a cache. Source database change transactions are captured and batched together for efficient data transfer. On receipt at a target replica system, the batch of transactions within a message is separated and separate apply transactions corresponding to the source transactions are performed in parallel. A ‘transaction processed’ table is updated to reflect apply processing for each apply transaction. This table provides a confirmation of the status of each transaction that can be used during recovery processing to prevent re-apply of an apply transaction. The table can also be used to determine when it is safe to delete an incoming message from persistent storage on the target system, and to facilitate one-phase commit processing.