The Dispatcher controls the sequence in which steps are executed. It also passes the steps to the BYNET to be distributed to the AMP database management software as follows:
The Dispatcher receives concrete steps from gncApply. The Dispatcher places the first step on the BYNET; tells the BYNET whether the step is for one AMP, several AMPS, or all AMPs; and waits for a completion response.Whenever possible, Teradata Database performs steps in parallel to enhance performance. If there are no dependencies between a step and the following step, the following step can be dispatched before the first step completes, and the two execute in parallel. If there is a dependency, for example, the following step requires as input the data produced by the first step, then the following step cannot be dispatched until the first step completes.
The Dispatcher receives a completion response from all expected AMPs and places the next step on the BYNET. It continues to do this until all the AMP steps associated with a request are done.