Normalization

Normalization is the process of structuring the data in a relational database to ensure that there is Parsimony of data. The main objective of normalization is to arrange the database in such a way that it eliminates data redundancy and depicts the interrelation between data entities correctly. This process entails the fragmentation of a database into two or more tables as well as the establishment of relationships between the tables for the sake of enhancing uniformity and performance. 

Key Characteristics of Normalization 

1. Minimizing Redundancy: Another goal of normalization is to reduce the data redundancy, this is the data which is repeated in different tables. This is because normalization removes data redundancy which in turn lowers the storage space needed for data as well as minimises the occurrence of data anomalies. 
2. Improving Data Integrity: It is a concept that defines the quality of data within a database, as to their accuracy and compatibility. Normalization ensures that data is well structured to help in avoiding certain data anomalies that may occur due to updates, deletions or insertion of new data.
3. Defining Clear Relationships: Normalization is a process of arranging data into tables in terms of the relationship between the entities. These relationships may be depicted by the use of foreign key which helps to maintain the integrity of the related data in the various tables. 
4. Normalization Forms: The normalization process can be divided into a number of stages also known as the ‘normal forms’ where certain conditions have to be fulfilled. The above mentioned normal structures are the First Normal Form (1NF), Second Normal Form (2NF) and Third Normal Form (3NF). But there are other normal forms which include the Boyce-Codd Normal Form (BCNF) and so on but the third normal form is more than adequate. 

The Normalization Process 

First Normal Form (1NF): 

• Eliminate Repeating Groups: In 1 NF, the table structure is further normalized in a way that each column should contain domain data only and non repetitive. This eliminates repeating groups and it also removes redundancy and duplicate data and stores data in its most detailed level. 
• Unique Identifiers: Every row in the table should be assigned with a key which is often a primary key that can be used to identify that particular row. 

Second Normal Form (2NF): 

• Remove Partial Dependencies: A table is in 2NF if the table is in 1NF and each non-key attribute is dependent on the primary key. This means that each non-key attribute should be functionally dependent on the whole of the primary key and not just a part of it especially where the primary key is composite. 
• Splitting Data: If a non-key attribute is partial dependent on a part of the composite key, then it has to be moved to the another table and thus will decrease partial dependencies. 

Third Normal Form (3NF): 

• Eliminate Transitive Dependencies: A table is in 3NF if it is in 2NF and none of the attributes depends on the other attributes but on the primary key. That is, non-key attributes should not be a function of other non-key attributes. If they do, then these attributes have to be shifted to another table. 
• Data Independence: This form is designed to enhance the data structure whereby each non-key attribute is directly linked with the primary key thus eliminating the concept of transitive dependencies. 

Boyce-Codd Normal Form (BCNF): 

• Stricter Version of 3NF: BCNF is a higher form of 3NF which takes care of some anomalies not covered by 3NF and those arise when a table has more than one candidate key. A table is said to be in BCNF if the table is in 3NF and each of the FDs in the table must hold with a superkey. 

Advantages of Normalization 

1. Reduced Data Redundancy: Redundant data is removed in normalization hence saves storage space and prevent data anomalies that could be caused by duplicate entry of data. 
2. Improved Data Integrity: Normalization is a technique of making the data consistent across the database by defining the relationship between the tables and creating the keys to reflect the relationships. 
3. Simplified Maintenance: This is because in normalized databases the data is stored in a manner that reduces the possibility of data anomalies. Changes, Removals and Additions can be done in a more convenient way and with minimal mistakes. 
4. Efficient Data Queries: Normalization can enhance the query performance since less amount of data has to be retrieved. It has been observed that when the data is well structured and has clear relationship, then it can be retrieved easily and quickly. 
5. Data Flexibility: The normalized databases are also more flexible as compared to the non-normalized databases. When new data requirements are gradually introduced to the system, normalised structure enables one to create new tables or alter existing ones without affecting the whole structure of the database. 

Disadvantages and Considerations 

1. Complexity: Normalization can also lead to increased level of complexity in the database design especially for large and complex systems. Since the data is split across different tables, the number of queries, or Joins that are needed to get specific data, will always be more and this may lead to longer and also more complicated query statements. 
2. Performance Overhead: In highly normalized databases, a disadvantage of large number of tables is experienced when joining many tables, and this can severely affect the efficiency especially when working with large query or large system.Denormalization which is the process of reintroducing redundancy may be adopted in some cases to enhance performance. 
3. Query Complexity: Normalization helps to eliminate redundancy in the database but at the same time it complicates the process of querying as data is usually scattered across different tables and to retrieve it, one has to join them. This can be quite cumbersome to the developers and users who require to write or interpret such queries. 
4. Initial Design Effort: Normalisation is a process of organizing the data in a database and hence it is a crucial process which needs to be planned and done systematically. It is more time consuming and may require a lot of effort especially in the case of intricate or not very clearly stated requirements to normalize the database properly. 

Conclusion 

To put it in simple terms, Normalization is the process of structuring data that is stored in a relational database in such a way that it reduces the duplication of data as well as the incidence of data anomalies. Normalization also involves breaking the data into several associated tables and eliminating redundancy in data storage hence making the database more consistent, efficient and easily manageable. Although normalization is helpful in removing redundancy and enhancing integrity, it has several drawbacks including complexity and possible slowing down of performance. The above-discussed normalization requires balancing between the provision of an efficient and effectively normalized data structure and the ease of retrieving data as well as the performance of the system.