SAP MDG data model: A walk-through

SAP MDG solution essentially has the following main components:
- Workflow
- Data model
- User interface
- Validations and derivations
- Replication

Lets focus on the MDG data model in this post.
The data created (or modified) within MDG exists in two states:
- Active (approved, in terms of process) and available to be used by processes within client sytems (SAP ERP most commonly).
- Inactive data (that ing throughs still movi the approval process) that is persisted in the Staging area.

The tables, for the Staging area is automatically generated from the data model. The MDG implementer can view data within these tables at any time [SE16]. This is a good context to introduce the terms Flex and Reuse. These are two alternate approaches to MDG implementation. In the case of Flex, both the Active and Staging tables are generated as part of MDG data modelling. In case of Reuse (as opposed to Flex scenario), the tables for active data are not generated. The underlying ERP tables (that lie outside the scope of MDG) are used to store activated data. In other words, when data gets activated, the active data is copied to the ERP tables.

For now, lets consider just the tables used to save Staging data. This way, the below discussion is relevant for both Flex and Reuse scenarios. To get the table names,
- execute the standard ABAP report usmd_data_model [SE38]
- select the MDG data model, for instance MM.
- Next screen displays the list of generated table names.
The details include both the logical and physical table names.

Use the physical table names to view data [SE16].
The table contents show the Master Data as they move through the create or change Change Request process (decided by the underlying Workflow template in use).