Database Management
Reference Manual
Introduction to Database Concepts
: Secondary Hierarchies
Secondary Hierarchies
An element can only exist once in the primary data hierarchy. Secondary hierarchies, such as GPSETs, allow elements to appear more than once in the overall hierarchy. For example a PIPE will appear below a ZONE in the primary hierarchy. The same PIPE may also be added to a GPSET element. This is useful for collecting elements according to different criteria.
The diagram below shows a typical multi hierarchy where the secondary links are dotted.
Most commands will work on secondary hierarchies. For example, if /GPSET1 is added to a 3D view then this is equivalent to adding both /VESS1 and /PUMP2 to the 3D view. However, there are exceptions to this. In particular deleting a GROUP will not delete the GROUP members; thus deleting /GPSET1 will not delete /VESS1 and /PUMP2.
Unlike the Primary hierarchy, secondary hierarchies may span different DBs.
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