When to use HDAM and PHDAM
HDAM and PHDAM databases are typically used for direct access to database records.
The randomizing module provides fast access to the root segment (and therefore the database record). HDAM and PHDAM databases also give you fast access to paths of segments as specified in the DBD in a database record. For example, in the following figure, if physical child pointers are used, they can be followed to reach segments B, C, D, or E. A hierarchical search of segments in the database record is bypassed. Segment B does not need to be accessed to get to segments C, D, or E. And segment D does not need to be accessed to get to segment E. Only segment A must be accessed to get to segment B or C. And only segments A and C must be accessed to get to segments D or E.
