Specifying when

After specifying at least one Insert into, Delete from , or Update of event, you can create an expression that must evaluate to true to satisfy the conditions of the trigger specification. Enter an expression in the When field that will be evaluated after the other events have occurred. If the When expression evaluates to true, the conditions of the trigger specification are met and the map is run. If the When expression is not true, the state is restored to what it was prior to the occurrence of any events. When row-based triggering is used, all of the changed rows will be batched together for subsequent processing after the event is re-triggered and the When clause has been satisfied.

When using column-based triggering, batch processing does not occur.