The workload event Arrivals tracks how many SQL requests are classified into a workload. You specify the time period: hour, minute, or second, and how many requests arriving in that time period trigger an event. Arrivals tracks arrivals only, not what happens to the request afterward, including throttling or demotion to another workload.
- Higher than usual request volumes. In a disaster, there can be more telephone calls and related requests. The DBA can use a change health condition action to adjust workload management rules automatically so that critical work can complete.
- A lull in request arrivals. A lull over the weekend should trigger an event with notification so someone can investigate. This prevents a weekend backlog of requests from turning into a flood of work on Monday morning.
Arrival rates can vary greatly. That is why Teradata recommends that DBAs use the Averaging qualification method for Arrivals and specify an appropriately long qualifying period. For example, some workloads may receive requests in bursts. If the bursts occur every 10 minutes, a DBA should use an Averaging interval that is a factor of 10 minutes (for example, 10, 20, or 30 minutes).