Relational Data Model.

Relational Data Model  

Relational model stores the data in the form of table. It consists of three major components.

1. The set of relations and set of domains that defines the way data can be represented.
2. Integrity rules that defines the procedure to protect the data.
3. The operations that can be performed on the table.
   

Advantages:

1. Ease of use: 
• Any information as tables consisting of rows and columns is much easier to understand .
2. Flexibility: 
• Different tables from which information has to be linked and extracted can be easily. 
3. Security: 
• Security control and authorization can also be implemented more easily by moving sensitive attributes in a given table into a separate relation with its own authorization controls.
4. Data Independence: 
• Data independence is achieved more easily with normalization structure used in a relational database than in the more complicated tree or network structure.
5. Data Manipulation Language: 
• The possibility of responding to query by means of a language based on relational algebra and relational calculus 
• Example: SQL is easy in the relational database approach.

Disadvantages :

1. Performance: 
• A major constraint and therefore disadvantage in the use of relational database system is machine performance. 
• If the number of tables between which relationships to be established are large and the tables themselves effect the performance in responding to the sql queries.
2. Physical Storage Consumption:
• With an interactive system, for example an operation like join would depend upon the physical storage also. It is, therefore common in relational databases to tune the databases and in such a case the physical data layout would be chosen so as to give good performance in the most frequently run operations. 
• Therefore would naturally result in the fact that the lays frequently run operations would tend to become even more shared.
3. Slow extraction of meaning from data:  
• if the data is naturally organized in a hierarchical manner and stored as such, the hierarchical approach may give quick meaning for that data.