Explanation/Reference:
Explanation:
The bulk load operation can be done by setting up a file watcher, then raise the event to inform the scheduler, it is kind of application based event.
After the bulk load job, you can use Scheduler raised event, e.g. JOB COMPLETE, to fire the index rebuild job.
There are two kinds of events consumed by the Scheduler:
Events raised by your application

An application can raise an event to be consumed by the Scheduler. The Scheduler reacts to the event by starting a job. For example, when an inventory tracking system notices that the inventory has gone below a certain threshold, it can raise an event that starts an inventory replenishment job.
See "Starting Jobs with Events Raised by Your Application".
File arrival events raised by a file watcher

You can create a file watcher-a Scheduler object introduced in Oracle Database 11g Release 2-to watch for the arrival of a file on a system. You can then configure a job to start when the file watcher detects the presence of the file. For example, a data warehouse for a chain of stores loads data from end- of-day revenue reports uploaded from the point-of-sale systems in the stores. The data warehouse load job starts each time a new end-of-day report arrives.