What are the features of a hierarchical database?
The main structures used by the hierarchical model are record types and parent-child relationship between a parent record type and a child record type. Access to lower level data elements must first access their parents. Relationships are strictly hierarchical in that a record type can participate as child in at most one parent-child relationship type. This restriction makes it difficult to represent a database where numerous relationships exist. While storage and retrieval are very fast, it is difficult to query a hierarchical database, and impossible to build decision support systems based on it.
