The network traffic between the application and the database server is one of the key factors of your application performance. If we can reduce the traffic, it will help us improve the performance of the application. The fetch size is the number of rows retrieved from the database at one time. It depends on the JDBC driver. The default fetch size of most of the JDBC drivers is 10. In normal JDBC programming, if you want to retrieve 1,000 rows, then you will need 100 network round-trips between the application and database server to retrieve all of the rows. It will increase the network traffic, and also impact performance. But if we set the fetch size to 100, then the number of network round-trips will be 10. This will greatly improve the performance of your application.

Many frameworks, such as Spring or Hibernate, give you very convenient APIs to do this....