Visualization modes of the IMS DBD editor

You can use the IMS DBD editor to plan and design database description (DBD) changes to support application requirements. For example, to develop an application to access related data from multiple IMS databases, you can use the IMS DBD editor to visualize the structure of a logical database that is formed from two or more DBDs.

You can visualize IMS databases by using the IMS DBD editor in the following visualization modes:

Edit view
For this mode, click the Edit view icon (Icon for Edit view).

The default mode when a database model is opened in the IMS DBD editor, and the only mode that allows editing. Shows a visual representation of a single physical or logical DBD, and the segment hierarchy of the database. For a logical DBD, the editor also shows concatenated segments. A concatenated segment represents segments from two DBDs that are associated through a logical relationship. A concatenated segment can be accessed by an application program as a segment in a physical DBD.

Related DBDs view
For this mode, click the Related DBDs view icon (Icon for Related DBDs view).
Shows the physical DBD, along with other DBDs that it has logical relationships with. A logical relationship is graphically represented by an arrow from the bottom of the logical parent segment to the top of the logical child segment.
Figure 1. Relationship between logical parent and child segments
Screen of logical parent and child segments, with an arrow from the bottom of the logical parent segment to the top of the logical child segment
Logical DBD modeler view
For this mode, click the Logical DBD modeler view icon (Icon for Logical DBD modeler view).

Shows the different data structures that are possible given the existing secondary indexes and logical relationships that are defined for a given DBD.

Secondary indexes
Segments that are labelled as targets of a secondary index are defined in the DBD as secondary index target segments. You can enter the Logical DBD modeler view mode by selecting either the root segment or a secondary index target segment and clicking the Logical DBD modeler view button located in the top right portion of the editor. If you select a non-root secondary index target segment and click the Logical DBD modeler view button, then the secondary data structure is displayed. The secondary index target segment is displayed as the root segment of the secondary data structure.
Logical relationships
Segments that are labelled as logical child segments are part of a logical relationship. In the Logical DBD modeler view mode, you can right-click the logical child segment and select Visualize as > Concatenated segment. The data structure that is possible as a result of the given logical relationship is displayed.




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