※This sample exam is different from those that appear in the actual OSS-DB Exam.
To simplify data normalization, it means that data can be easily managed by eliminating duplication of data and redundancy.
There are various degrees of normalization, and there are the first normal form, the second normal form, the third normal form, the Boyce-Codd normal form, the fourth normal form, and the fifth normal form as representative ones.
In designing relational databases, especially the third normal form is very important, so please learn about the normalization method.
When data is normalized, data duplication and redundancy are eliminated, so it is possible to prevent data inconsistency and loss due to data addition, update, deletion, etc.
In other words, the maintainability of data is improved.
However, if you normalize, SQL statements become complicated and search performance may deteriorate because you will join more tables and retrieve data.
To optimize performance, it is also done to denormalize the data.
As key columns and indexes are added instead of eliminating duplicate data, the size of the data does not necessarily become smaller due to normalization.
Therefore, the correct answer is C.