A method for applying changes to a standby system is described in which multiple
apply tasks or "slaves" are scheduled to changes from redo logs, especially those
changes in large transactions, in parallel and as soon as they are encountered
in the logs. To foster data convergence, a partial ordering may be imposed on the
transactions so that those transactions that actually depend on others are forced
to wait on the transactions they are dependent upon commit. To foster read consistency,
synchronization points may be periodically established, at which points a read
consistent state of the standby database system can be obtained-all without adversely
impact the throughput of the system.