Hierarchical database model is one of the oldest database models, dating from late 1950s. One of the first hierarchical database information management systems (IMS) was developed jointly by North American Rockwell Company and IBM. This model is like a structure of a tree with the records forming the nodes and fields forming the branches of the tree.
Advantages and disadvantages of Hierarchical model
1.Simplicity: Since the database is based on the hierarchical structure, the relationship between the various layers is logically simple.
2.Data Security :Hierarchical model was the first database model that offered the data security that is provided by the dbms.
3.Data Integrity: Since it is based on the parent child relationship, there is always a link between the parent segment and the child segment under it.
4.Efficiency: It is very efficient because when the database contains a large number of 1:N relationship and when the user require large number of transaction.
Disadvantages of Hierarchical model:
1. Implementation complexity: Although it is simple and easy to design, it is quite complex to implement.
2.Database Management Problem: If you make any changes in the database structure, then you need to make changes in the entire application program that access the database.
3.Lack of Structural Independence: there is lack of structural independence because when we change the structure then it becomes compulsory to change the application too.
4.Operational Anomalies: Hierarchical model suffers from the insert, delete and update anomalies, also retrieval operation is difficult.