Event execution in a database mirroring or read-only scale-out system

Events can execute either on only the primary or root server, or they can execute on the primary server, the mirror server and the copy nodes. By default, events are not fired on the mirror database; event firing only starts after a failover from the primary server to the mirror server takes place.

You specify where an event can execute when you create or alter the event. Use the FOR clause of the CREATE EVENT or ALTER EVENT statement, to specify where an event can fire.

DatabaseStart event type

By default an event that uses the DatabaseStart event type only executes when a server becomes the primary server for the database. However, if you have specified that the event can run on the primary server, mirror server, and the copy nodes, then the event is executed when any database starts. If in a mirroring system this event did not run when the database started (for example, the database was running before the event was created), then the event can execute during a failover.

For example if you start a database mirroring system, create a DatabaseStart event with the FOR ALL clause, and then stop the primary server, you cause a failover. In this example, the event executes on the new primary server. The DatabaseStart event does not execute during subsequent failovers.

Event execution in a database mirroring or read-only scale-out system

DatabaseStart event type

See also