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
().
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
().
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
Logical DBD modeler view
For this mode, click the Logical DBD modeler view icon
().
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.
).
).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.
).