Hierarchical Model with examples and characteristics

Hierarchical Model with examples and characteristics

In this tutorial, we will learn about the followings;

  1. Hierarchical model
  2. Examples of hierarchical model
  3. Characteristics of hierarchical model

What is Hierarchical Model?

All the records have a parent to child relationship.

Give an example of the hierarchical model?

IMS is hierarchical database management system.Information management system IMS introduced by IBM in 1968.

hierarchical database model
Figure: hierarchical model

What are characteristics of the hierarchical model?

Does not supports many to many relationships:

Deletion problem:

  • If a parent is deleted, the child has also deleted automatically.

Data hierarchy:

  • Data can be represented as a hierarchical tree as can be seen in the figure.

Each child record can have only one parent record:

Hierarchy through pointer:

  • Pointers are used to link the records. Pointer determines that which record is parent record and which one is child record.

Minimize disk input and output:

  • Parent and child records are stored close to each other on the storage device. It helps to minimize the hard disk input and disk output.

Fast navigation:

  • Due to the short distance between parent to child, database access time and performance is improved. Navigation through the database is very fast in a hierarchical model.

Predefined relationships between records:

  • All relationships are predefined. Root nodes, parents, and child are predefined in the database schema.

Difficult to re-organize:

  • It is difficult to re-organize the database due to hierarchy. It is difficult to re-organize because parent to child relationships can be disturbed.

 

Test Your Understandings

1. Hierarchical model supports many to many relationships  ? YES / NO

Answer - Click Here:
NO

2. Hierarchical model is more complex than Network model  ? YES / NO

Answer - Click Here:
No

2. One child can have only parent entity ? YES / NO

Answer - Click Here:
Yes