You can define a set of partition keys in a Stream data set to test how data flow processing is distributed across Data Flow service nodes in a multinode decision management environment by using the default load balancer. For example, you can test whether the intended number and type of partitions negatively affect the processing of a Data Flow rule that references an event strategy.
If the Stream data set feeds event data to an Event Strategy rule, you can define only a single partition key for that data set. That partition key must be the same as the event key that is defined in the Real-Time Data shape on the Event Strategy form. Otherwise, when you run the Data Flow, it fails.
An active Data Flow rule that references a Stream data set with least one partition key defined continues processing when nodes are added or removed from the cluster, for example, as a result of node failure or an intentional change in the node topology. However, any data that was not yet processed on the failed or disconnected node is lost.