* Constraint is broken to accommodate the following situation:
* 1. Event with specific timestamp is scheduled.
* 2. Event is unscheduled.
* 3. Event is rescheduled.
* 4. Event runs, or is unscheduled, but unique constraint prevents query from succeeding.
* 5. Event retains `pending` status and runs again. Repeat steps 4 and 5 until `a8c_cron_control_purge_completed_events` runs and removes the entry from step 2.
*/
$updates=array(
'status'=>self::STATUS_COMPLETED,
'instance'=>wp_rand(1000000,999999999),// Breaks unique constraint, and can be recreated from entry's remaining data
'instance'=>mt_rand(1000000,999999999),// Breaks unique constraint, and can be recreated from entry's remaining data