Unit 11 Section 11: Restructured Hierarchy and Secondary Data Structure

This video describes first describes how a restructured (also called an “inverted”) hierarchy is useful for overcoming certain restrictions because it permits the ability to identify the key of all segments up to the root so that the alternate PCB (without PROCSEQ=) can be used to insert or delete parent segments.

This video also talks about a secondary data structure, which occurs when entry to a database via a secondary index that is pointing to a target segment other than a root causes a restructured hierarchy.