Evolution of Relational Database From Hierarchical Database
Author: Sharath Reddy
Database programs are primarily designed so that they are able to store and manipulate information. However, the efficiency of a database depends upon how fluently it can relate between different units of information, either within the database or between several databases. The data present in one database needs to be available to the data of another database in order to maintain continuity.
The hierarchical database model follows a schema resembling a tree. It is a simpler database model where the relation is established between parent and child nodes. The tree structure is tough to maintain when the volume of data increases. This structure is easy to implement and comprehend.
It is best demonstrated when people store files within folders. Therefore hierarchical database system had to be discarded when the job was to store large volumes of data since the probability of data corruption and loss was high in such a system. Many-to-one or many-to-many relationships become hard to be implemented through parent child relationship in cases where there is a child node which may have more than one parent node.
The problems that arise in the parent-child relationship of a hierarchical model are deftly averted in the relational database model. The relational database does not follow a simple tree structure and is instead based on formation of tables. Data is entered in tabular formats where each table has a primary key. A primary key is generally a column in the table which contains values that are unique and distinct from other records in the table.
The other attributes of a record in the table can be easily identified with the help of a primary key. For example, if a website registers the names of the students of a certain institute, then for every student a unique identification number is issued which acts as the primary key in the database. Therefore the problems occurring due to many to one or one to many relations can be easily avoided through implementation of relational database. Each table happens to have a key that is able to relate with the values entered in other tables with the help of some common keys.
The relational database is suited for organizations where records with high complexity need to be added and manipulated very quickly. On the other hand the hierarchical database model comes into use and serves more efficiently when there is large number of simple transactions that needs to be processed. Therefore both the database systems find their use according to the given conditions and environments where they are implemented.
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