When the correlator shuts down, the default behavior is that all state is lost. When you restart the correlator, no state from the previous time the correlator was running is available. You can change this default behavior by using correlator persistence.

Correlator persistence means that the correlator automatically periodically takes a snapshot of its current state and saves it on disk. When you shut down and restart that correlator, the correlator restores the most recent saved state.

To enable persistence, you indicate in your EPL code which monitors you want to be persistent. Optionally, you can write actions that the correlator executes as part of the recovery process. When code is injected for a persistence application, the correlator that the code is injected into must have been started with a persistence option.

Persistent monitors must be written in EPL. State in chunks, with a few exceptions, cannot be persistent.

To protect the security of personal data, see Handling personal data "at rest" in the correlator persistence and JMS datastores.

If you plan to install a new version of Apama, see Persistence database backup.