Database optimization is an essential step to improve application performance. Typically, developers normalize a relational database to reduce data redundancy and enhance data integrity. However, sometimes normalizing a database makes the applications run slower as queries have to get data from multiple tables through joins and other techniques.
So, to improve database performance developers work backwards and start database denormalization. Denormalization is a database optimization technique in which we add redundant data to one or more tables. This can help us avoid costly joins in a relational database. Note that denormalization does not mean not doing normalization. It is an optimization technique that is applied after doing normalization.