The JPA specification and Hibernate, as its most popular implementation, claim to provide database portability. That means you don’t need to change your persistence code or mapping annotations when connecting your application to a different RDBMS. They achieve that by providing an automated object-relational mapping, an API that abstracts from the executed SQL statements, and…
Spring Data JPA’s standard repositories provide a set of methods that handle common operations used by most persistence layers. That saves us a lot of time and allows us to focus on our business logic. But we also need to ask ourselves which of these methods we want to use. You need to know how…
By default, Spring Data JDBC expects the database to provide a primary key value for every new record. The easiest way to achieve that is to use an autoincremented column. We used that in the Introduction to Spring Data JDBC guide. But what do you do if your table model uses a database sequence instead?…
Most developers prefer numerical primary keys because they are efficient to use and easy to generate. But that doesn’t mean that a primary key has to be a number. UUIDs, for example, have gained some popularity over recent years. The main advantage of a UUID is its (practical) global uniqueness which provides a huge advantage…
Flyway’s SQL-script based database migration is more than powerful enough for most use cases. But sometimes, you must take it one step further to adapt your existing data to the new database schema. E.g., you might need to extract data from blobs or read JSON documents so that you can fill the newly added database…
