Mappings contain one or more target load order groups. A target load order group is the collection of source qualifiers, transformations, and targets linked together in a mapping. Each target load order group contains one or more source pipelines. A source pipeline consists of a source qualifier and all of the transformations and target instances that receive data from that source qualifier.
By default, the DTM reads sources in a target load order group concurrently, and it processes target load order groups sequentially. You can configure the order that the DTM processes target load order groups.
The following figure shows a mapping that contains two target load order groups and three source pipelines:
In the mapping, the DTM processes the target load order groups sequentially. It first processes Target Load Order Group 1 by reading Source A and Source B at the same time. When it finishes processing Target Load Order Group 1, the DTM begins to process Target Load Order Group 2 by reading Source C.