Natural key

The advantages of using a natural key to uniquely identify records in a relation include less disk space usage, the natural key is an attribute that is related to the business or the real world so in most cases, it is already being stored in the relation which saves disk space as compared to creating a new column for storing the surrogate key. Another advantage of using natural keys is that it simplifies enforcement of data quality, and they are easier to relate to real life while designing the database system. They simplify the quality of data as using a natural key that is unique in the real world ensures that there cannot be multiple records with the same primary key. Comparing the database schema to a real world scenario is a huge part of designing a database schema and when a natural key is being used in the tables of the database, it makes it easy for the database engineer to engineer the database system. == Disadvantages ==

Usage of natural keys as unique identifiers in a table has one main disadvantage which is the change of business rules or the change of rules of the attribute in the real world. The definition of the structure of the natural key attribute might change in the future. For example if there is a table storing the information about US citizens, the Social Security Number would act as the natural key, Social Security Number being the natural key might pose a problem in the future if the US government changes the structure of the Social Security Number and increases the number of digits in the SSN due to some reason. In that case, the database administrator will have to change the schema of the table and perhaps also update the records of the table. In other cases, this can prevent improvements of the system altogether due to too extensive effort required for the change, e.g., the inability of the knowledge management software Confluence, to represent multiple pages with the same title. ==References==