What are the salient features of Hierarchical database ? Describe briefly.

The hierarchical data model was the first database model to be created, it was an improvement on general file-processing systems because it allows the creation of logical relationships between information in a database. However, this structure also has its disadvantages that led to the eventual development of the network model and the relational model. Features of Hierarchical Database are: The data are stored as records which are connected to one another through links. Relationship between records are relatively fixed by the structure i.e. hierarchical databases are less flexible. Records are logically structured in inverted tree pattern. Each record and node in hierarchy is related to other records in a parent child relationship. It mandates that each child record has only one parent whereas each parent record can have one or more child records. Parent and child records are stored close to each other on storage device and hence helps in reducing the hard disk input and disk output. Due to short distance between parent and child database access time and performance is improved. It implements one-to-one and one-to-many relationships. It cannot support Many to Many relationships. Since process is structured, hence day to day operation can be fast. If a parent is deleted the child also gets deleted automatically. Ad-Hoc queries require different relationship other than already defined. Thus it is difficult and time consuming to solve.